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Quantitative sensory testing: Effect of site and skin temperature on thermal thresholds
Abstract
To determine the effect of different sites and local skin temperature on thermal thresholds.
Cool and warm detection and cold and heat pain thresholds were compared in 46 normal volunteers at the thenar eminence (TE), dorsum of the hand (DH), volar surface of the wrist (VW) and dorsum of the foot (DF).
The hand is more sensitive than the foot for cool and warm. TE is more sensitive for warm than DH and VW but the difference is clinically negligible. DH and VW are equally sensitive to warm. TE, DH, and VW are equally sensitive to cool. Inter-individual variance is smallest at TE. Warm and cool thresholds are independent of local skin temperature (range of 27-37 degrees C). TE is less sensitive for cold pain but otherwise the hand and the foot are equally sensitive to thermal pain.
Testing of thermal thresholds in normal subjects can be adequately conducted at several sites at the hand, however, TE is preferred given the small inter-individual variability. TE may be preferred for evaluating hyperalgesia to cold given its higher threshold. Warming or cooling of the skin is unnecessary within the range normally encountered in routine clinical evaluation.
... Historically thermal threshold testing reliability varies significantly among healthy participants, especially for thermal detection thresholds [23,28,46]. There are many factors that could contribute to this including the small sample size of this study and other studies, the differences in testing location on the body, the different baseline temperature (measured skin temperature instead of a set temperature), nonstandardized testing, the reaction time of the participant which needs to be quicker for thermal detection thresholds compared to thermal pain thresholds, outside distractions or unknown room and skin temperatures [44,[47][48][49]. The prototype design is working towards improving the reliability with improved technology including the skin temperature and room temperature sensors which could have an advantage over coins, ice and test tube testing methods as the temperature of the thermode is always known [15][16][17]. ...
... One of the big differences between the TSA-2 and the prototype is the baseline temperatures. The baseline temperature at which the thermode begins each cycle can influence results [47,48,51]. For HPT and CPT, both devices (prototype and TSA-2) started at the measured skin temperature, which could have contributed to the validity results. ...
... A previous study found that there was no significant difference in CPT results when the baseline temperature was 32 C or 36 C [52]. For the WDT and CDT tests, the TSA-2 was started at a common starting temperature of 32 C [14], while the mean temperature reported by the prototype was 33.96 C. [47,48,53]. Colder thermode temperatures can lead to increased detection of decreasing temperatures while a warmer starting thermode can result in improved detection of increasing temperatures [51]. ...
Thermal threshold testing is important for evaluating the thermal function of small-fibre nerve types C and A-delta. This study investigated the reliability and validity of a novel nerve testing device (NNTD) in evaluating thermal detection and thermal pain thresholds. Test-retest reliability of the NNTD and its concurrent validity compared to the current technology (Medoc TSA-2, Advanced Thermosensory Stimulator, Israel) were investigated among 10 healthy participants. Each participant was tested for the warm detection threshold (WDT), cold detection threshold (CDT), hot pain threshold (HPT) and cold pain threshold (CPT) on the medial forearm with NNTD for two trials and the Medoc TSA-2 for one trial over two consecutive days. Intraclass Correlation Coefficient values, Standard Error of Measurement and Bland Altman plots were calculated for test-retest reliability. One-way ANOVA and Bland Altman plots were calculated for validity. The test-retest reliability of the NNTD was good for CPT (ICC = 0.88), moderate for WDT (ICC = 0.545) and HPT (ICC = 0.710). The NNTD was valid for both trials of HPT and CPT and one trial for WDT compared to the Medoc TSA-2. In conclusion, the NNTD showed good to moderate reliability and was found to be valid compared to the Medoc TSA-2.
... Heat pain, skin blood flow, sweating, and heart rate are also the possible candidates to find the effects. In particular, the latter parameters may need higher temperature elevation than the thermal threshold in human skin (12). Moreover, changes in skin temperature and skin blood flow are most likely to be informative if they are observed as two-dimensional images by cameras. ...
... Although it was observed in the exposure experiment with 28 GHz MMW, the local MMW exposure at 1,800 W/m 2 of IPD elevated about 7 • C of skin temperature in the human forearm (14). Therefore, at least this IPD value was likely to be necessary to evoke changes in several physiological parameters, because the warm detection temperature was reported to be 32.2-40.7 • C in the human skins of several body regions, which means the temperature rise was 0.2-8.7 • C from the starting temperature of 32 • C (12). Based on these findings, the maximum output power of MMW amplifier was estimated as 4 W or more in the case of using the single lens antenna of 60 GHz. ...
... This range of temperature change seemed to be enough for warm detection reported in the skins such as thenar and dorsal hand (32.3-35.3 • C) (12). Therefore, it suggests that the local MMW exposure that we expected for human studies is realized in the human skin. ...
The global spread of 5th generation (5G) wireless systems causes some concern about health effects of millimeter waves (MMW). To investigate biological effects of local exposure to 5G-MMW on human body, a novel 60 GHz band exposure setup was developed, and its performance was validated. A spatial synthetic beam-type exposure setup using two dielectric lens antennas was proposed to achieve high intensity 60 GHz irradiation to the target area of human skin. Variety distributions and intensities of electromagnetic fields at the exposed area, which is modified by incident angles of the combined beams, were simulated using finite-difference time-domain methods. The exposure performance we estimated was verified by temperature elevations of surface in a physical arm-shaped silicone phantom during the MMW exposure. The interference fringes generated in the exposed area due to the combined two-directional beam radiations were observed both in the simulation and in the phantom experiment but eliminated by applying an orthogonalizing polarized feeding structure. Under these exposure conditions, the local temperature changes, which could evoke warmth sensations, were obtained at the target area of the human forearm skin, which means the achievement of exposure performance we intended.
... 26,[31][32][33] Compared to lower body sites, upper sites are more sensitive to thermal and mechanical stimuli. 33,34 Fatigue, anxiety and depression typically are associated with increased reports of pain. [35][36][37][38] Most studies of healthy African Americans included college students and siblings of SCD patients with unknown trait status. ...
... Results from previous studies have shown a consistent pattern of lower heat pain thresholds in females, but the magnitude of these differences has been quite variable. 11,29,31,33,34,65,66 We adjusted for multiplicity and found that only WD differed. ...
... MPTh values were not significantly different by sex, age, or upper and lower body sites, which is consistent with previous findings for sex, 27,31,64,71 age, 67,70,72 and upper and lower body sites. 33,34 Although many body sites have been used in QST studies, upper versus lower body site comparisons have been consistent across studies and over time. Some investigators have reported no significant difference in thermal threshold differences between upper extremity and lower extremities after controlling for multiplicity. ...
Purpose
Only a few studies have reported quantitative sensory testing (QST) reference values for healthy African Americans, and those studies are limited in sample size and age of participants. The study purpose was to characterize QST values in healthy, pain-free African American adults and older adults whose prior pain experiences and psychological status were also measured. We examined the QST values for differences by sex, age, and body test site.
Patients and methods
A cross-sectional sample of 124 pain-free African American adults (age 18–69 years, 49% female) completed demographic and self-reported pain, fatigue and psychosocial measures. QST was performed to obtain thermal and mechanical responses and associated pain intensity levels.
Results
We found thermal detection values at the anterior forearm were (29.2 °C±1.6) for cool detection (CD) and (34.5 °C±1.2) for warm detection (WD). At that site the sample had cold pain threshold (CPTh) (26.3 °C±5.0), heat pain threshold (HPTh) (37.8 °C±3.6), and mechanical pain thresholds (MPTH) (16.7±22.2 grams of force, gF). There was a significant between sex difference for WD, with women being more sensitive (q=0.027). Lower body sites were less sensitive than upper body sites across all thermal modalities (q<0.003), but not for the mechanical modality.
Conclusion
The QST values from this protocol at the anterior forearm indicate that the healthy African American adults had average thermal pain thresholds close to the temperature of adaptation and average MPTh under 20 gF. Differences in responses to thermal and mechanical stimuli for upper verses lower body were consistent with prior research.
... 4 The Thresholds of Cutaneous Thermal Sensation and Related Factors 4.1 The Thresholds for Non-Noxious Warmth Sensation and Noxious Heat Sensation. Depending on the body sites and testing methods, the thresholds for a person to start to have warm sensation are between 33 C and 35 C [32][33][34][35][36][37]. When the local skin temperature reaches 42-45 C, people start to have pain sensations. ...
... Multiple studies have found that the temperature thresholds for warm or heat pain can be lower for proximal than distal body parts [32,50]. However, Hagander et al. (2000) did not find significant difference between proximal and distal skin locations [34]. ...
... Multiple reasons can contribute to the inconsistency in the results, including types of stimuli, testing methods, experimental conditions, individual differences, skin area, age, gender, and body sites, type of device, rate of temperature change, probe size, psychophysical algorithm, race, body mass index, smoking/ alcohol consumption, and local skin temperature [34,36,[51][52][53]. Sections 4.2.1-4.2.14 will provide an overview of the effect of each factor on thermal sensation. ...
Literature was reviewed and summarized on a few topics including: existing standards about the limits of devices' surface temperature, recent studies on the devices that caused discomfort and skin damage, human thermal sensation thresholds, the factors that affect thermal sensation, and the subjective ratings in the studies of thermal sensation. At the end, recent research on human subjective and objective testing was also summarized. The purpose of the review is to give an overview of cutaneous human thermal sensation and comfort, and how they are affected by the surface temperature of electronic devices.
... In sensory vibration tests, the forces between the oscillating probe and the anatomical location are apparently greater during standing than during sitting conditions. In this regard, previous studies demonstrated that higher contact forces (by additionally applied masses) reduce vibration perception thresholds (VPTs) during sitting (Cassella, Ashford, & Kavanagh-Sharp, 2000;Hagander, Midani, Kuskowski, & Parry, 2000;Lowenthal & Derek, 1987). In contrast, another study did not find effects of increasing contact forces on VPTs when measuring dorsal foot areas during sitting (Hagander et al., 2000). ...
... In this regard, previous studies demonstrated that higher contact forces (by additionally applied masses) reduce vibration perception thresholds (VPTs) during sitting (Cassella, Ashford, & Kavanagh-Sharp, 2000;Hagander, Midani, Kuskowski, & Parry, 2000;Lowenthal & Derek, 1987). In contrast, another study did not find effects of increasing contact forces on VPTs when measuring dorsal foot areas during sitting (Hagander et al., 2000). However, these results may not directly be applied to standing conditions. ...
... Contact force is an influencing factor for VPT measurements. Hagander et al. (2000) investigated the effects of vertically applied masses (30-100 g) on dorsal VPTs at 100 Hz and did not find any differences. Cassella et al. (2000) varied masses (0-100 g) applied to the head of a neurothesiometer and found lower VPTs as masses increased. ...
Monitoring skin sensitivity is studied to clarify its relationship on balance. Measuring skin sensitivity is performed when subjects are sitting or lying, whereas balance tests are measured during standing. However, afferent signal processing and subsequent efferent responses can be altered by different body positions. Therefore, this study investigated whether vibration perception thresholds (VPTs) are influenced by body positions. Sixty-six healthy subjects (41♀; 25♂) participated in this study. Five measurements of VPTs were performed at each of the three analyzed anatomical locations (heel, first metatarsal head, hallux) of the right plantar foot under two randomized conditions: during sitting and standing. The contact force applied to the probe was measured and controlled within the five trials. Contact forces between the probe and the foot were higher during standing. However, no differences in VPTs were found between conditions. This indicates that VPTs are not different during standing compared to sitting, contrary to our expectations. We conclude that higher forces did not induce increased receptor activity. Since no differences were found between thresholds, future clinical studies can implement plantar VPT tests during sitting in association with balance tests during standing.
... S kin sensitivity to various stimuli is known to vary among different body areas. 1,2 Among reasons, morphologic differences in local receptor densities or local vascularization have been highlighted, 3,4 whereas other causes such as the local thickness of the epidermis 5 or the local skin temperature 6 have been rather discouraged. The normal variation in skin sensitivity to various stimuli, however, is distinguished from a pathologic variation as a symptom of neuropathy. ...
... 13 [8], WUR [1], and PPT [10]), measured at the control side as in that study; hypersensitization with capsaicin had been applied at the test side, which made these data unsuitable for the present comparative analysis. When using references values for the dorsal side of the hand, instead of those of the foot, 42 values met the criteria of an abnormal finding (CDT [6], WDT [12], TSL [7], CPT [4], HPT [0], MDT [0], MPT [0], MPS [6], WUR [2], and PPT [5]). This is almost a third more; however, the difference was still not significant (Wilcoxon signed rank test: W=42.5, P = 0.5882), whereas a tendency of the QST parameters to differ with respect to the occurrence of abnormal values in healthy individuals was again observed (Kruskal-Wallis test: w 2 = 14.998, df = 9, P = 0.09099). ...
... 13 [8], WUR [1], and PPT [10]), measured at the control side as in that study; hypersensitization with capsaicin had been applied at the test side, which made these data unsuitable for the present comparative analysis. When using references values for the dorsal side of the hand, instead of those of the foot, 42 values met the criteria of an abnormal finding (CDT [6], WDT [12], TSL [7], CPT [4], HPT [0], MDT [0], MPT [0], MPS [6], WUR [2], and PPT [5]). This is almost a third more; however, the difference was still not significant (Wilcoxon signed rank test: W=42.5, P = 0.5882), whereas a tendency of the QST parameters to differ with respect to the occurrence of abnormal values in healthy individuals was again observed (Kruskal-Wallis test: w 2 = 14.998, df = 9, P = 0.09099). ...
Background:
Skin sensitivity to sensory stimuli varies among different body areas. A standardized clinical quantitative sensory testing (QST) battery, established for the diagnosis of neuropathic pain, was used to assess whether the magnitude of differences between test sites reaches clinical significance.
Methods:
Ten different sensory QST measures derived from thermal and mechanical stimuli were obtained from 21 healthy volunteers (10 men) and used to create somatosensory profiles bilateral from the dorsum of the hands (the standard area for the assessment of normative values for the upper extremities as proposed by the German Research Network on Neuropathic Pain) and bilateral at volar forearms as a neighboring nonstandard area. The parameters obtained were statistically compared between test sites.
Results:
Three of the 10 QST parameters differed significantly with respect to the "body area," that is, warmth detection, thermal sensory limen, and mechanical pain thresholds. After z-transformation and interpretation according to the QST battery's standard instructions, 22 abnormal values were obtained at the hand. Applying the same procedure to parameters assessed at the nonstandard site forearm, that is, z-transforming them to the reference values for the hand, 24 measurements values emerged as abnormal, which was not significantly different compared with the hand (P=0.4185).
Conclusions:
Sensory differences between neighboring body areas are statistically significant, reproducing prior knowledge. This has to be considered in scientific assessments where a small variation of the tested body areas may not be an option. However, the magnitude of these differences was below the difference in sensory parameters that is judged as abnormal, indicating a robustness of the QST instrument against protocol deviations with respect to the test area when using the method of comparison with a 95 % confidence interval of a reference dataset.
... Both the stimulus duration and size of the stimulus area can affect thermal sensation [17][18][19]. The heat pain threshold decreases significantly as contact duration increases from 2.5 to 10 s [17,18]. ...
... Meh and Deni slič [20] showed that at the thenar eminence, the heat pain threshold was 37.7 C for female participants and 40.2 C for males, with a probe surface of 25 Â 50 mm. However, with a smaller probe surface of 30 Â 30 mm, the heat pain threshold was higher at 43.4 C [19], and with a probe of 25 Â 25 mm, the threshold was 45.6 C [16]. Similarly, at the lower medial calf, a larger thermode (12.5 cm 2 ) produced a significantly lower mean warm threshold of 35.5 C than a smaller thermode (3.75 cm 2 ) of 36.5 C [12]. ...
... For each surface temperature level, participants were asked to hold the prototype in the way they would normally hold a tablet computer for 90 s, and to report their thermal sensation and thermal comfort three times at each temperature level (0, 45, and 90 s). The duration of 90 s was to extend the test durations of most previous laboratory thermal test studies [15][16][17]19,20,[32][33][34][35]. However, since each participant will be tested with all the surface temperatures for twice, and for each level of temperature, they need to report three times, the duration was limited for 90 s to prevent the participants from fatigue. ...
A series of experiments was conducted to investigate participant thermal responses to different surface temperatures, from 34 to 44 °C, for a simulated tablet computer in different ambient temperatures (13 °C, 23 °C, and 33 °C). Two subjective measures, thermal sensations and thermal comfort, were reported by the participants. Within the same ambient temperature, participants' thermal sensation and discomfort scores were positively correlated with the increase of surface temperature (higher surface temperatures gave warmer sensations). Thermal comfort also decreases with the increase of surface temperature in the tested range. In addition, ambient temperature moderated the effect of surface temperature on participants' thermal sensation scores. The higher surface temperature of 44 °C was rated warmer at 33 °C than 13 °C, but lower surface temperatures (34-38 °C) were rated less warm at 33 °C than 13 °C. On the other hand, all the surface temperatures were perceived less uncomfortable in an environment at 13 °C environment than at 33 °C. The findings can be used to set limits for future tablet computer heat dissipation designs to improve user's thermal experiences.
... As arthritis sufferers can spend considerable time wearing therapeutic gloves, it is important to maintain their positive comfort sensations during wear. Psychophysical studies have shown that sensitivities to thermal stimulation are not uniformly distributed across the body regions and also differ between individuals [18][19][20]. Li, Petrini (18) reported a high-resolution topographical mapping of warm and cold sensitivities of the hand in healthy participants. They found that thermal sensitivity distribution in the hand is not uniformly distributed; the palm is more sensitive than the fingers to both warm and cold stimuli. ...
... Further, considerable variations between the participants were also found for the cold discomfort thresholds in contrast to very low variations for heat discomfort thresholds. The cold sensation is known to be more subjective to variation in human and thus difficult to evaluate [19,20,42]. ...
... Due to spatial summation (Kandel et al., 2012;Schmidt, 1978), the size of the stimulation probe is crucial (Dyck et al., 1993;Hilz et al., 1998Hilz et al., , 1999, as well as differences in the number of receptors (Guergova and Dufour, 2011;Kandel et al., 2012;Schmidt, 1978) and in the density of nerve terminals between body areas (Chang et al, 2004). Also the velocity of temperature change during stimulation (Palmer et al., 2000;Pertovaara and Kojo, 1985), and the initial skin temperature is of importance (Hagander et al., 2000;Hilz et al., 1995), together with factors such as gender, age and the site of stimulation (Blankenburg et al., 2010;Defrin et al., 2006;Dyck et al., 1993;Hafner et al., 2015;Hagander et al., 2000;Hilz et al., 1999;Huang et al., 2010;Lin et al., 2005;Magerl et al., 2010;Meier et al., 2001;Yarnitsky, 1997;Yarnitsky and Sprecher, 1994). ...
... Due to spatial summation (Kandel et al., 2012;Schmidt, 1978), the size of the stimulation probe is crucial (Dyck et al., 1993;Hilz et al., 1998Hilz et al., , 1999, as well as differences in the number of receptors (Guergova and Dufour, 2011;Kandel et al., 2012;Schmidt, 1978) and in the density of nerve terminals between body areas (Chang et al, 2004). Also the velocity of temperature change during stimulation (Palmer et al., 2000;Pertovaara and Kojo, 1985), and the initial skin temperature is of importance (Hagander et al., 2000;Hilz et al., 1995), together with factors such as gender, age and the site of stimulation (Blankenburg et al., 2010;Defrin et al., 2006;Dyck et al., 1993;Hafner et al., 2015;Hagander et al., 2000;Hilz et al., 1999;Huang et al., 2010;Lin et al., 2005;Magerl et al., 2010;Meier et al., 2001;Yarnitsky, 1997;Yarnitsky and Sprecher, 1994). ...
Objective
Thermal quantitative sensory testing with the ‘Method-of-Limits’ is an established rationale for detection of small nerve fiber dysfunction, but adequate reference values are crucial for such evaluations, regardless of the underlying cause. This study assessed reference data for cold- (CPT) and warm- (WPT) perception thresholds at both proximal and distal sites in eight body regions of the lower and upper extremities, all determined within the same test session for each subject.
Methods
Seventy-five healthy subjects (aged 16–72 years) were tested according to the method-of-limit for CPT and WPT at the dorsum of the foot, the medial and lateral lower leg, the ventral thigh, the thenar eminence, the radial and ulnar part of the lower arm, and the anterior deltoid part of the upper arm.
Results
Overall, thermal perception thresholds (TPT) varied with test location, but were higher in the lower than in the upper part of the body, also WPT were generally higher than CPT. TPT at the dorsum foot highly correlated with age, while inconsistent correlations were noted between TPT and age or height at other tested locations.
Conclusion
This study describes for the first time reference values at eight defined body regions, at both proximal and distal sites.
Significance
The report enables refined evaluations of general small nerve fiber function, as assessed by quantitative thermal sensory testing with the Method-of-Limits.
... For the assessment of the cold and warm detection thresholds, the temperature was decreased or 3 increased at a rate of 1°C/s, with an inter-stimulus interval ranging from 3 to 5s 7,51 . The temperature 4 was changed at a rate of 3°C/s with an interval of 20s for the assessment of cold pain and heat pain 5 thresholds 24,26 . The safety cut-off temperatures were set at 0°C and 50°C. ...
... A validated modified Roland Morris Questionnaire (RMQ) was used 30,50 . This questionnaire contains 22 24 items of which participants chose those that applied to them. The total number of items chosen 23 was calculated; the greater the score, the more severe the disability 6,30 . ...
Healthy humans can be divided into the pain adaptive (PA) and the pain nonadaptive (PNA) groups; PA showed a greater decrease in pain rating to a cold pressor test (CPT) than PNA. This study examined if the dichotomy of pain adaptability existed in individuals with chronic musculoskeletal pain. CPTs at 2°C and 7°C were used to assess the status of pain adaptability in participants with either chronic nonspecific low back pain or knee osteoarthritis. The participants' potency of conditioned pain modulation (CPM) and local inhibition were measured. The strengths of pain adaptability at both CPTs were highly correlated. PA and PNA did not differ in their demographic characteristics, pain thresholds from thermal and pressure stimuli, or potency of local inhibition or CPM. PA reached their maximum pain faster than PNA (t41 = -2.76, P < .01), and had a gradual reduction of pain unpleasantness over 7 days whereas PNA did not (F6,246 = 3.01, P = .01). The dichotomy of pain adaptability exists in musculoskeletal pain patients. Consistent with the healthy human study, the strength of pain adaptability and potency of CPM are not related. Pain adaptability could be another form of endogenous pain inhibition of which clinical implication is yet to be understood.
Perspective:
The dichotomy of pain adaptability was identified in healthy humans. The current study confirms that this dichotomy also exists in individuals with chronic musculoskeletal pain, and could be reliably assessed with CPTs at 2°C and 7°C. Similar to the healthy human study, pain adaptability is not associated with CPM, and may reflect the temporal aspect of pain inhibition.
... These regions offered good subcutaneous conditions and enough space for a 4 Â 4 cm injection square. Our baseline QST data from these regions showed comparable results for heat pain thresholds to published normative data of other regions of the arm [23,24,27]. Our cold pain thresholds were at least 7 jC higher than in other regions of the arm [27]. ...
... Our baseline QST data from these regions showed comparable results for heat pain thresholds to published normative data of other regions of the arm [23,24,27]. Our cold pain thresholds were at least 7 jC higher than in other regions of the arm [27]. Such sitedependence was explained by anatomical differences, such as in cold receptor density, thickness of the dermis, and in sympathetic innervation [28 -30]. ...
... Smartphone devices are in close contact with the human hand and there are differences in heat sensation thresholds between different areas of the human hand. Hagander, L. G. et al. (2000) experimentally noted that the greater thenar eminence has a higher sensitivity than the rest of the hand and the fingertips have a lower sensitivity. The impact of smartphone heat issues on user experience in real-world scenarios can be reduced if heat distribution is based on the user's preferred Grasping posture information. ...
The ergonomic design of the thermal comfort of smartphones requires a greater understanding of the user's preferred grasping postures. This study examined the users' preferred grasping postures in three one-handed and high-heat-generating smartphone applications(short video browsing, video chatting, and video recording). The grasping postures of 50 participants in 3 smartphone application scenarios are photographed. The grasping position is encoded by the smartphone locations (left: L, right: R, top: T, bottom: B, front: F, back: K) and the number of fingers at each contact position. The grasping posture frequency distribution of smartphone application scenarios will be of use to guide the determination of the optimal thermal layout of smartphones in specific application scenarios.
... In this section, we introduced novel and interesting findings from a series of studies on the cutaneous thermal sensitivity of tropical and temperate indigenes, but there are certain limitations to these studies, especially their methodologies. Many factors underlie the measurement of thermal thresholds as covariates: methods (method of limit vs. method of level), type of heating modes (contact vs. radiant vs. immersion), adaptation temperature (cold vs. neutral vs. warm), rate of temperature increase (0.1, 0.5, 1, or 2 °C/s), stimulated surface area (from just a few millimeters to more than 10 cm 2 ), age (the young vs. the elderly), ancestry (European vs. African American), gender (male vs. female), total body fat (the lean vs. the obese), skin type (hairy vs. glabrous skin), etc. Higher cutaneous warm thresholds are associated with a faster rate of temperature increase, smaller stimulated area, and the elderly [70,71]. All values should be interpreted with these types of methodological considerations. ...
This review mainly aimed to introduce the findings of research projects comparing the responses of tropical and temperate indigenes to heat. From a questionnaire survey on thermal sensation and comfort of Indonesians and Japanese, we found that the thermal descriptor “cool” in tropical indigenes connotes a thermally comfortable feeling, suggesting that linguistic heat acclimatization exists on a cognitive level. Ten male students born and raised in Malaysia were invited to Fukuoka, Japan, and compared their responses with 10 Japanese male students with matched physical fitness and morphological characteristics. Cutaneous thermal sensitivity: The sensitivities were measured at 28 °C. The forehead warm sensitivity was significantly blunted in Malaysians. The less sensitivity to the warmth of tropical indigenes is advantageous in respect to withstanding heat stress with less discomfort and a greater ability to work in hot climates. Passive heat stress: Thermoregulatory responses, especially sweating, were investigated, during the lower leg hot bathing (42 °C for 60 min). The rectal temperature at rest was higher in Malaysians and increased smaller during immersion. There was no significant difference in the total amount of sweating between the two groups, while the local sweating on the forehead and thighs was lesser in Malaysians, suggesting distribution of sweating was different from Japanese. Exercise: Malaysian showed a significantly smaller increase in their rectal temperature during 55% maximal exercise for 60 min in heat (32 °C 70% relative humidity), even with a similar sweating and skin blood flow response in Japanese. The better heat tolerance in Malaysians could be explained by the greater convective heat transfer from the body core to the skin due to the greater core-to-skin temperature gradient. In addition, when they were hydrated, Malaysian participants showed better body fluid regulation with smaller reduction in plasma volume at the end of the exercise compared to the non-hydrated condition, whereas Japanese showed no difference between hydration conditions. We further investigated the de-acclimatization of heat adaptation by longitudinal observation on the heat tolerance of international students who had moved from tropical areas to Fukuoka for several years.
... However, we chose two consecutive nights of partial, not total, SR, because partial SR is more tolerable and a more realistic model for insomnia and/or short sleep, and because both partial SR (50), and total sleep deprivation (29), have been shown to increase pain sensitivity in healthy subjects. The HPTs measured in this study were low compared to other reported means and reference values, although other data materials also seem to have a portion of relatively low HPT with lower limits extending below 37 C (51,52). Despite the mean difference, the 5% confidence range among our controls (35.5 C), was identical to the young female group in Magerl et al. (52) (35.6 C). ...
Objective
There is an unexplained association between disturbed sleep and migraine. In this blinded crossover study, we investigate if experimental sleep restriction has a different effect on pain thresholds and suprathreshold pain in interictal migraineurs and controls.
Methods
Forearm heat pain thresholds and tolerance thresholds, and trapezius pressure pain thresholds and suprathreshold pain were measured in 39 interictal migraineurs and 31 healthy controls after two consecutive nights of partial sleep restriction and after habitual sleep.
Results
The effect of sleep restriction was not significantly different between interictal migraineurs and controls in the primary analyses. Pressure pain thresholds tended to be lower (i.e., increased pain sensitivity) after sleep restriction in interictal migraineurs compared to controls with a 48-hour preictal-interictal cut-off (p = 0.061). We found decreased pain thresholds after sleep restriction in two of seven migraine subgroup comparisons: heat pain thresholds decreased in migraineurs with lower pain intensity during attacks (p = 0.005) and pressure pain thresholds decreased in migraineurs with higher severity of photophobia during attacks (p = 0.031). Heat pain thresholds tended to decrease after sleep restriction in sleep-related migraine (p = 0.060). Sleep restriction did not affect suprathreshold pain measurements in either group.
Conclusion
This study could not provide strong evidence for an increased effect of sleep restriction on pain sensitivity in migraineurs compared to healthy controls. There might be a slightly increased effect of sleep restriction in migraineurs, detectable using large samples or more pronounced in certain migraine subgroups.
... The lowest temperature recognized as W or H was considered the threshold of W or H. The highest temperature recognized as C was considered the threshold of C. In all thermal experiments, the starting temperature was 32°C [11][12][13][14][15], the lower limit was 10°C, and the upper limit was 50°C. All thermal stimuli applied were increased or decreased by 1°C every 10-15 s. ...
Fifty-four patients diagnosed with paresthesia on one side of the lower lip or skin in the chin area, were examined by multiple sensory tests and assessed self-reported subjective symptoms and the psychological state through questionnaires. Additionally, they were followed over time. Each sensory test threshold was evaluated and classified according to the individual way of scoring system, and the average sensory score (ASS) was used to analyze the correlation between self-reported symptoms and psychological state. On the second visit, all sensory test results had improved. The ASS was positively correlated with the pain questionnaire on the first visit; however, it did not correlate with psychological state or personality. There was a positive correlation between neuroticism and anxiety scores. The index of change (IC) of the ASS over time did not correlate with the IC of patients’ self-reported symptoms or mental state. The IC of ASS data improved in all patients, but self-reported subjective symptoms did not show signs of improvement in all patients. When patients were divided into two groups according to age or sex, older females showed significantly more improvement than younger males on the psychological test.
... A recent user experience research [57] showed that user burdens, including physical discomfort and pain, negatively influence overall user experiences. Prior human perception studies showed that a person's thermal threshold for warm sensation is in the range of 33.0 • C to 35.0 • C [28]. At a temperature higher than this threshold, a user is likely to feel discomfort and starts to feel pain at around 42-45 • C [37]. ...
Overheating smartphones could hamper user experiences. While there have been numerous reports on smartphone overheating, a systematic measurement and user experience study on the thermal aspect of smartphones is missing. Using thermal imaging cameras, we measure and analyze the temperatures of various smartphones running diverse application workloads such as voice calling, video recording, video chatting, and 3D online gaming. Our experiments show that running popular applications such as video chat, could raise the smartphone's surface temperature to over 50$^\circ$C in only 10 minutes, which could easily cause thermal pain to users. Recent ubiquitous scenarios such as augmented reality and mobile deep learning also have considerable thermal issues. We then perform a user study to examine when the users perceive heat discomfort from the smartphones and how they react to overheating. Most of our user study participants reported considerable thermal discomfort while playing a mobile game, and that overheating disrupted interaction flows. With this in mind, we devise a smartphone surface temperature prediction model, by using only system statistics and internal sensor values. Our evaluation showed high prediction accuracy with root-mean-square errors of less than 2$^\circ$C. We discuss several insights from our findings and recommendations for user experience, OS design, and developer support for better user-thermal interactions.
... QST measures the perceived intensity of a given stimulus (i.e., the subjective experience) while controlling the intensity of the stimulus (Dyck et al., 1993;McGrath and Brown, 2006;Hansson et al., 2007;Arendt-Nielsen and Yarnitsky, 2009). Moreover, it is used to indirectly evaluate the underlying sensory functioning by testing a spectrum of peripheral nerve system functions, as well as revealing abnormalities related to disorders of the central nervous system (CNS; Bartlett et al., 1998;Hagander et al., 2000;Arendt-Nielsen and Yarnitsky, 2009). Previous studies in our lab have used QST to evaluate somatosensory detection thresholds [i.e., the minimum intensity levels at which 50% of stimuli are recognized; International Association of the Study of Pain (IASP), 2017], including those of light touch, vibration, warm and cool sensations. ...
Sensory modulation disorder (SMD) affects sensory processing across single or multiple sensory systems. The sensory over-responsivity (SOR) subtype of SMD is manifested clinically as a condition in which non-painful stimuli are perceived as abnormally irritating, unpleasant, or even painful. Moreover, SOR interferes with participation in daily routines and activities (Dunn, 2007; Bar-Shalita et al., 2008; Chien et al., 2016), co-occurs with daily pain hyper-sensitivity, and reduces quality of life due to bodily pain. Laboratory behavioral studies have confirmed abnormal pain perception, as demonstrated by hyperalgesia and an enhanced lingering painful sensation, in children and adults with SMD. Advanced quantitative sensory testing (QST) has revealed the mechanisms of altered pain processing in SOR whereby despite the existence of normal peripheral sensory processing, there is enhanced facilitation of pain-transmitting pathways along with preserved but delayed inhibitory pain modulation. These findings point to central nervous system (CNS) involvement as the underlying mechanism of pain hypersensitivity in SOR. Based on the mutual central processing of both non-painful and painful sensory stimuli, we suggest shared mechanisms such as cortical hyper-excitation, an excitatory-inhibitory neuronal imbalance, and sensory modulation alterations. This is supported by novel findings indicating that SOR is a risk factor and comorbidity of chronic non-neuropathic pain disorders. This is the first review to summarize current empirical knowledge investigating SMD and pain, a sensory modality not yet part of the official SMD realm. We propose a neurophysiological mechanism-based model for the interrelation between pain and SMD. Embracing the pain domain could significantly contribute to the understanding of this condition’s pathogenesis and how it manifests in daily life, as well as suggesting the basis for future potential mechanism-based therapies.
... Studies did not show a significant difference between foot and hand for heat-induced and cold-induced pain thresholds. The mean heat-induced pain threshold in healthy subjects was around 43°C and cold-induced pain threshold varies from 11.7 to 16.2°C (Dyck et al. 1993;Hagander et al. 2000;Hansen et al. 1996). Cold-induced pain is the most variable modality which is the most difficult to evaluate. ...
Statistical Analysis All the graphs, calculations, and statistical analyses were performed using GraphPad Prism software version 8.0 for Mac (GraphPad Software, San Diego, CA, USA). To test whether the collected numerical data are normally distributed, the D’Agostino and Pearson, Anderson-Darling and Shapiro- Wilk normality tests were applied. Z-transformation of the QST data was performed using the following expression z = (x - µ)/s, where x corresponds to the individual variable fromthe datasets thatmust be normalized with z-transformation, while µ and s are the control group mean and standard deviation (SD), respectively. Z-value equal or higher than 2, also equal or lower than -2 indicates that variable significantly differs from the control group mean. The comparison of means between different groups of numerical variables was performed using one-way ANOVA. Homogeneity of variances was tested using Brown-Forsythe and Bartlett’s tests, and in a case of unequal SDs Brown-Forsythe and Welch ANOVA test was applied. If data were not normally distributed, the comparison of medians between different groups was switched to nonparametric one-way ANOVA on ranks or Kruskal-Wallis test followed by two-stage step-up method of Benjamini, Krieger and Yekutieli as post-hoc test. Because most of the data was distributed not normally, results are expressed as median and interquartile range (IQR) as dispersion characteristic, and p value less than 0.05 (p <0.05) was considered as statistically significant. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
... The sensitivity of the facial area to pain was found to be either higher [25] or similar to other body locations [26]. Distal parts were equally sensitive [27] or less sensitive than the proximal parts of the limb [25,26]. However, because the degree of sensitivity to noxious pain is uniform across the body, the comparison of pain sensitivity according to body location needs to be evaluated in a larger sample size. ...
Congenital melanocytic nevi need surgical excisions. However, the effect of the size and location of the nevi on pain and emergence agitation have yet to be studied. The objective of this study was to evaluate (1) the ideal parameter of the nevus size and (2) the effects of the size and location of the nevus on pain and emergence agitation. This observational study enrolled 100 children scheduled for an excision of a nevus under sevoflurane anesthesia. The parameters of the nevus size included the long diameter, the area before resection, the area of resection, and the proportion (the area of resection/total body surface). The nevus locations included the trunk, face, scalp, and extremities. The proportion of the nevi was the most ideal parameter in evaluating the pain and emergence agitation. A large size showed a higher emergence agitation than a small size (median (range); 6 (0–20) in small groups vs. 12.5 (0–20) in large groups, p = 0.021). However, the pain was comparable. The nevus location did not influence pain or emergence agitation. In a multivariate regression analysis, a younger age and an extensive excision were associated with higher pain and emergence agitation. In conclusion, large nevi induced more severe emergence agitation. However, the nevus location did not affect the outcome. In addition, a younger age was associated with pain and emergence agitation. Clinicians need to consider the proportion of nevi when managing children undergoing a nevus excision.
... Studies did not show a significant difference between foot and hand for heat-induced and cold-induced pain thresholds. The mean heat-induced pain threshold in healthy subjects was around 43°C and cold-induced pain threshold varies from 11.7 to 16.2°C (Dyck et al. 1993;Hagander et al. 2000;Hansen et al. 1996). Cold-induced pain is the most variable modality which is the most difficult to evaluate. ...
Human herpes virus-6 (HHV-6) and human herpes virus-7 (HHV-7) are immunomodulating viruses potentially affecting the nervous system. We evaluated the influence of HHV-6 and HHV-7 infections on fibromyalgia (FM) clinical course. Forty-three FM patients and 50 control group participants were enrolled. 39.50% (n = 17) FM patients had light A delta and C nerve fiber damage, 27.91% (n = 12) had severe A delta and C nerve fiber damage. 67.44% (n = 29) FM patients had loss of warm sensation in feet, loss of heat pain sensation, and increased cold pain sensation (34.90%, n = 15 in both findings). HHV-6 and HHV-7 genomic sequences in peripheral blood DNA in 23/43 (51.00%) and 34/43 (75.50%) of samples from FM patients and in 3/50 (6.00%) and 26/50 (52.00%) of samples from the control group individuals were detected. Active HHV-6 (plasma viremia) or HHV-7 infection was revealed only in FM patients (4/23, 17.40% and 4/34, 11.80%, respectively). A statistically significant moderate positive correlation was found between A delta and C nerve fiber damage severity and HHV-6 infection (p < 0.01, r = 0.410). 23/43 patients from the FM group and control group participants HHV-6 and 34/45 HHV-7 did have infection markers. A statistically significant moderate positive correlation was found between A delta and C nerve fiber damage severity and HHV-6 infection (p < 0.01, r = 0.410). No difference was found between detection frequency of persistent HHV-6 and HHV-7 infection between FM patients and the control group. Statistically significant correlation was observed between quantitation of changes in QST thermal modalities and HHV-6 infection. There was no correlation between A delta and C nerve fiber damage and HHV-7 infection.
... Standardized instructions were given before each measurement on all occasions. All procedures were completed within 10-15 min minimizing the effect of fatigue and loss of concentration (Hagander, Midani, Kuskowski, & Parry, 2000). Subjects, acupuncturists, physiotherapists, and the examiners were kept uninformed of the PPT scores throughout the study to prevent previous scores from influencing the results (Delaney & McKee, 1993). ...
Background and purpose:
Nonpharmacological therapies for tension-type headache (TTH) and cervicogenic cephalalgia are often a treatment choice, despite the weak to moderate evidence. The aim of this study was to compare the effectiveness of an acupuncture/stretching protocol versus acupuncture/stretching plus physiotherapy techniques, in patients with TTH cephalalgia.
Methods:
A single-blind, prospective, multicentre, randomized controlled trial was designed considering the pragmatic situation of administering such protocols and treating the 44 headache patients participating in this study. The patients were randomly assigned in 2 treatment groups (control group, n = 20, acupuncture/stretching; experimental group, n = 24, acupuncture/stretching plus physiotherapy) and completed 10 treatment sessions within 4 weeks with measurements taking place before treatment, after the fifth treatment and after the 10th treatment. The mechanical pressure pain threshold (PPT) was considered as the main outcome measure, using a mechanical algometer to measure 7 bilateral somatic points. Acupuncture in both groups included 17-20 acupuncture points, whereas stretching was initially taught and subsequently self-administered (self-stretches), following a standardized set of movements of the cervical spine. Physiotherapy consisted of microwave diathermy and myofascial release with hands-on techniques.
Results/findings:
An improvement was noted in both groups/treatments regarding the main outcome measure PPT, all the way from the first to fifth and the 10th treatment, at all measuring sites and at all measurements in both groups (p < .001). When comparing the 2 groups, differences were noted after the 10th treatment (p < .05).
Discussion:
In conclusion, patients with TTH headache were benefited from acupuncture and stretching but further PPT improvements were evidenced when physiotherapy hands-on techniques were added. In clinical terms, the combination of physiotherapy in the form of myofascial release and microwave diathermy with acupuncture and stretching in order to improve the analgesic effect (PPT) is strongly recommended.
... The stimuli consisted of thermal pulses delivered to the thenar eminence of each hand. We considered the thenar eminence for two reasons: first, cold and warm detection thresholds at the thenar eminence show low variability across participants, and second, the thenar eminence has a higher sensitivity than other regions of the hand for warm stimuli [1]. ...
Perceptual illusions enable designers to go beyond hardware limitations to create rich haptic content. Nevertheless, spatio-temporal interactions for thermal displays have not been studied thoroughly. We focus on the apparent motion of hot and cold thermal pulses delivered at the thenar eminence of both hands. Here we show that 1000 ms hot and cold thermal pulses overlapping for about 40% of their actuation time are likely to produce a continuous apparent motion sensation. Furthermore, we show that the quality of the illusion (defined as the motion's temporal continuity) was more sensitive to changes in SOA for cold pulses in relation to hot pulses.
... During both experiments, participants sat comfortably in a dimly lit room. An infrared thermometer was used to ensure that the skin temperature at the beginning of the experiment (main experiment: 31 Ϯ 2.2°C; control experiment: 32 Ϯ 1.8°C) was in the suggested range for thermal sensory testing (Hagander et al. 2000). During the recording, participants were exposed to white noise through headphones to cancel out ambient noise. ...
The protective function of pain depends on appropriate motor responses to avoid injury and promote recovery. The preparation and execution of motor responses is thus an essential part of pain. However, it is not yet fully understood how pain and motor processes interact in the brain. Here we used electroencephalography to investigate the effects of pain on motor preparation in the human brain. Twenty healthy human participants performed a motor task in which they performed button presses to stop increasingly painful thermal stimuli when they became intolerable. In another condition, participants performed button presses without concurrent stimulation. The results show that the amplitudes of preparatory event-related desynchronizations at alpha and beta frequencies did not differ between conditions. In contrast, the amplitude of the preparatory readiness potential was reduced when a button press was performed to stop a painful stimulus compared with a button press without concomitant pain. A control experiment with nonpainful thermal stimuli showed a similar reduction of the readiness potential when a button press was performed to stop a nonpainful thermal stimulus. Together, these findings indicate that painful and nonpainful thermal stimuli can similarly influence motor preparation in the human brain. Pain-specific effects on motor preparation in the human brain remain to be demonstrated.
NEW & NOTEWORTHY Pain is inherently linked to motor processes, but the interactions between pain and motor processes in the human brain are not yet fully understood. Using electroencephalography, we show that pain reduces movement-preparatory brain activity. Further results indicate that this effect is not pain specific but independent of the modality of stimulation.
... LDI Flare was shown to be reproducible and useful, correlating with nerve fiber density [6]. QTT of cooling and thermal thresholds is increasingly used for the evaluation of peripheral nervous system function in the clinical and research domains, mainly for confirmation of small nerve fiber neuropathy, and has been found to be reliable and reproducible [7]. Both of these methods are non-invasive, and can be performed at the bedside with immediate results at a reasonable cost. ...
Introduction
Small fiber neuropathy might be a part of typical mixed small and large fiber neuropathy, or a distinct entity, affecting exclusively small nerve fibers.
Objectives
Explore the utility of small nerve fiber testing in patients with clinical presentation suggesting small fiber neuropathy, with and without evidence for concomitant large fiber neuropathy.
Methods
Patients attending the neuromuscular clinic from 2012 to 2015 with a clinical presentation suggesting small nerve fiber impairment, who had Laser Doppler flare imaging (LDIFlare) and quantitative thermal testing (QTT) were evaluated for this study. Patients with clinical or electrophysiological evidence for concomitant large fiber neuropathy were not excluded.
Results
The sensitivities of LDIFlare, cooling and heat threshold testing were 64%, 36%, and 0% respectively for clinically highly suggestive small fiber neuropathy, 64%, 56%, and 19% respectively for mixed fiber neuropathy, and 86%, 79%, and 29% respectively for diabetic mixed fiber neuropathy.
Discussion
LDIFlare and cooling thresholds testing are non-invasive small nerve fiber testing modalities, with moderate performance in patients with small and mixed fiber neuropathy, and excellent performance in diabetic mixed fiber neuropathy.
... The decreased local skin temperature at the chest with passive heating might have the potential to influence the observations of the skin thermal sensation thresholds, since previous studies have suggested that skin thermal sensations are influenced by difference in local skin temperatures (Bartlett et al. 1998;Hilz et al. 1999). On the other hand, Hagander et al. (2000) have suggested that local skin temperature within a range of 27-37°C did not cause a significant effect on skin warm sensation threshold and had only a minor effect on skin cool sensation threshold, and several previous studies have also reported no effect of local skin temperature on thermal sensation threshold (Gelber et al. 1995;Sosenko et al. 1989). The discrepancies in the previous studies would be associated with the differences in the methodology; body region(s) assessed, types of measures used, and the types of stimuli (Guergova and Dufour 2011). ...
Thermal sensation represents the primary stimulus for behavioral and autonomic thermoregulation. We assessed whether the sensation of skin and core temperatures for the driving force of behavioral thermoregulation was modified by postural change from the supine (Sup) to sitting (Sit) during mild hyperthermia. Seventeen healthy young men underwent measurements of noticeable increase and decrease (±0.1 °C/s) of skin temperature (thresholds of warm and cold sensation on the skin, 6.25 cm(2) of area) at the forearm and chest and of the whole-body warm sensation in the Sup and Sit during normothermia (NT; esophageal temperature (Tes), ∼36.6 °C) and mild hyperthermia (HT; Tes, ∼37.2 °C; lower legs immersion in 42 °C of water). The threshold for cold sensation on the skin at chest was lower during HT than NT in the Sit (P < 0.05) but not in Sup, and at the forearm was lower during HT than NT in the Sup and further in Sit (both, P < 0.05), with interactive effects of temperature (NT vs. HT) × posture (Sup vs. Sit) (chest, P = 0.08; forearm, P < 0.05). The threshold for warm sensation on the skin at both sites remained unchanged with changes in body posture or temperature. The whole-body warm sensation was higher during HT than NT in both postures and higher in the Sit than Sup during both NT and HT (all, P < 0.05). Thus, thermal sensation during mild hyperthermia is modulated by postural change from supine to sitting to sense lesser cold on the skin and more whole-body warmth.
Extreme heat and its various impacts are a growing threat to cities and their residents, and it is increasingly clear that portfolios of solutions are needed to mitigate the resulting risks. Here we comprehensively evaluate and optimize the application of existing retro-reflective (RR) materials, which reflect incoming solar radiation back to the sky, on urban surfaces to cool them. Using detailed energy budget models, we show that RR walls and pavements decrease urban canyon surface temperatures by up to
20 °C and canyon air temperatures by up to 2.6 °C, outperforming highly reflective surfaces, with a notable improvement in pedestrian thermal comfort (up to 0.55 °C and 153 W m−2 reductions in human skin temperature and net radiative gain, respectively). We then develop optimized RR design
guidelines for diverse climatic conditions, latitudes, seasons and urban geometries. On the basis of our analysis, we recommend RR pavements for open, low-rise areas and propose specific RR wall design strategies for compact, high-rise areas.
The purpose of the present study was to evaluate body regional differences in cutaneous warmth and hotness thresholds in relation to radiant heat exposure. Fourteen male subjects participated in this study (age: 25 ± 5 y, height: 176.6 ± 5.5 cm, body weight: 70 ± 5.8 kg). Cutaneous warmth and hotness thresholds were measured on the forehead, neck, chest, abdomen, upper back, lower back, upper arm, forearm, palm, back of hand, front thigh, shin, top of foot, buttock, back thigh, calf, and sole. The forehead (34.8 ± 0.2 °C), lower back (34.1 ± 1.2 °C) and palm (34.3 ± 0.7 °C) had the highest warmth thresholds, whereas the foot (29.8 ± 1.9 °C) and sole (28.0 ± 2.1 °C) had the lowest values among the 17 regions (P<0.001). Higher warmth thresholds were related to higher initial skin temperatures (Tsk) (r=0.972, P<0.001). Increases in Tsk for detecting warmth sensation were smaller for the lower back with a rise of 0.2 ± 0.4 °C and the abdomen (0.3 ± 0.3 °C) than for the buttock (0.9 ± 0.8 °C) and sole (0.8 ± 0.6 °C) (P<0.05). Increases in Tsk for detecting hotness sensation ranged from 0.5 to 1.5 °C. Warmth and hotness thresholds on the abdomen or sole had significant relationships with body mass index, indicating that the overweight are less sensitive to detecting radiant heat on the abdomen or sole. Thermal thresholds from radiant heat exposure of 100 cm2 were lower than the values from conductive heat exposure of 6.25 cm2, which might be explained by the effect of spatial summation.
Modern head mounted displays are high performance wearable computers. However, the effect of headset temperature on user thermal discomfort is rarely discussed. Here, user ratings of thermal discomfort during a VR game across three different thermal conditions between 28° – 43° C was measured. Perceived thermal discomfort ratings, administered every 12-minutes, decreased over time and as the HMD microclimate tem-perature (MCT) increased. Additionally, thermal discomfort increased more quickly for MCTs above 38° C. The HIGH temperature condition (MCT > 38° C) was rated uncomfortable after 24-mintues. Post- – pre-VR forehead temperatures in both the MID and HIGH conditions were significantly higher than in the LOW condition. The current findings suggest users perceive MCT temperatures above 38° C as uncomfortable. To maximize thermal comfort for extended use manufacturers of VR headsets should limit MCT to < 38° C.
In de perifere circulatie van arteriën en venen kunnen door vernauwingen, verwijdingen, traumatische letsels en afwijkende onderlinge verbindingen symptomen van ischemie, aneurysmata, bloedingen of arterioveneuze fistels optreden. Circulatieproblemen kunnen in het hele lichaam ontstaan, maar manifesteren zich frequent aan de onderste extremiteiten. Het oriënterend onderzoek bestaat uit inspectie, palpatie en auscultatie, eventueel aangevuld met de capillaire refilltest. Daarnaast wordt het onderzoek besproken bij een aantal ziektebeelden van de perifere circulatie: chronische veneuze insufficiëntie, veneuze trombose, perifeer arterieel vaatlijden, acute arteriële afsluiting, trombosebeen, compartimentsyndroom, blue toe en diabetische voet. Bij het onderzoek op indicatie komen het arteriële doppleronderzoek ter bepaling van de enkel-armindex en de Allen-test aan de orde.
More than 50% of individuals develop chronic pain following traumatic brain injury (TBI). Research suggests that a significant portion of post-TBI chronic pain conditions is neuropathic in nature, yet the relationship between neuropathic pain, psychological distress, and somatosensory function following TBI is not fully understood. This study evaluated neuropathic pain symptoms, psychological and somatosensory function, and psychosocial factors in individuals with TBI (TBI, N = 38). A two-step cluster analysis was used to identify phenotypes based on the Neuropathic Pain Symptom Inventory and Beck's Anxiety Inventory scores. Phenotypes were then compared on pain characteristics, psychological and somatosensory function, and psychosocial factors. Our analyses resulted in two different neuropathic pain phenotypes: (1) Moderate neuropathic pain severity and anxiety scores (MNP-AS, N = 11); and (2) mild or no neuropathic pain symptoms and anxiety scores (LNP-AS, N = 27). Furthermore, the MNP-AS group exhibited greater depression, PTSD, pain severity, and affective distress scores than the LNP-AS group. In addition, thermal somatosensory function (difference between thermal pain and perception thresholds) was significantly lower in the MNP-AS compared to the LNP-AS group. Our findings suggest that neuropathic pain symptoms are relatively common after TBI and are not only associated with greater psychosocial distress but also with abnormal function of central pain processing pathways.
Temporal summation of second pain (TSSP) has been suggested as a psychophysical index for central sensitization, one of the critical mechanisms in the chronification of pain. However, there is no gold standard for protocols to measure TSSP. The purpose was to establish the stimulus intensity for measuring TSSP. Female patients with chronic myofascial temporomandibular disorders pain (n = 16) and healthy female volunteers with no pain (n = 15) participated. Pain thresholds (PT °C) were measured, and repetitive heat stimuli at three stimulus intensities (PT °C, PT + 1 °C, PT + 2 °C) were applied. TSSP parameters were quantified as TSSP magnitude (TSm) and TSSP frequency (TSf). In healthy female volunteers, pain ratings significantly decreased at PT °C (p < 0.050), besides TSm and TSf at PT + 2 °C were significantly higher than those at PT °C (p < 0.025). In chronic pain patients, pain ratings significantly increased at PT + 1 °C and PT + 2 °C (p < 0.050). At PT + 2 °C, TSm and TSf in chronic pain patients were significantly higher than those in healthy volunteers (p < 0.050). It could be helpful to measure TSSP with the stimulus intensity adjusted individually to the patient’s pain thresholds + 2 °C for assessing central sensitization.
A paradoxical heat sensation (PHS) is the misperception of warmth when the skin is cooled. PHS is uncommon in healthy individuals but common in patients with neuropathy and is associated with reduced thermal sensitivity. Identifying conditions that contribute to PHS may indirectly help us understand why some patients experience PHS. We hypothesized that pre-warming increased the number of PHS and that pre-cooling had minimal effect on PHS. We tested 100 healthy participants’ thermal sensitivity on the dorsum of their feet by measuring detection and pain thresholds to cold and warm stimuli and PHS. PHS was measured using the thermal sensory limen (TSL) procedure from the quantitative sensory testing protocol of the German Research Network on Neuropathic Pain and by using a modified TSL protocol (mTSL). In the mTSL we examined the participants’ thermal detection and PHS after pre-warming of 38°C and 44°C and pre-cooling of 26°C and 20°C. Compared to a baseline condition, the number of PHS responders was significantly increased after pre-cooling (20°C: RR = 1.9 (1.1; 3.3), p = 0.023 and 26°C: RR = 1.9 (1.2; 3.2), p = 0.017), but not significantly after pre-warming (38°C: RR = 1.5 (0.86; 2.8), p = 0.21 and 44°C: RR = 1.7 (.995; 2.9), p = 0.078). Pre-warming and pre-cooling increased the detection threshold of both cold and warm temperatures. We discussed these findings in relation to thermal sensory mechanisms and possible PHS mechanisms. In conclusion, PHS and thermosensation are closely related and pre-cooling can induce PHS responses in healthy individuals.
With the advancement of wireless technologies and electronic/electrical devices, humans are exposed to more complicated electric, magnetic, and electromagnetic fields (EMF), which has raised public concerns on potential health effects. Researchers have recently conducted a series of studies on diverse exposure scenarios. In addition, international standard organizations have revised safety guidelines and standards (1). These recent results and practices can enhance our knowledge in assessing health risks from the exposure to EMF (2). This Research Topic consists of 14 articles (one review article, two brief research report articles, and 11 original research articles) published in the Radiation and Health section of Frontiers in Public Health.
Background: Central sensitization (CS) of the nociceptive system is linked to a disparity between the perceived pain intensity and the severity of the tissue damage in many chronic pain conditions. Temporal summation of second pain (TSSP) has been suggested as a psychophysical index for CS. However, there is no golden standard for protocols to measure TSSP. The purpose was to establish the stimulus intensity for measuring TSSP to obtain the best assessment of CS in healthy individuals and patients with chronic pain.
Methods: Women patients with chronic myofascial temporomandibular disorders pain (n = 16) and healthy women volunteers with no pain (n = 15) participated. First, TSSP response patterns in healthy volunteers with no pain were tested. Second, differences in TSSP between groups were investigated. Pain thresholds (PT °C) were measured, and repetitive heat stimuli at three stimulus intensities (PT °C, PT+1 °C, PT+2 °C) were applied. TSSP parameters were quantified as TSSP magnitude (TSm), TSSP frequency (TSf). Generalized linear mixed-effect models with repetitive stimuli on pain ratings were conducted.
Results: In healthy women volunteers, pain ratings significantly decreased at PT ℃ (P < .050), besides TSm and TSf at PT+2 ℃ were significantly higher than those at PT ℃ (P < .025). In chronic pain patients, pain ratings significantly increased at PT+1 ℃ and PT+2 ℃ (P < .050). At PT+2 ℃, TSm and TSf in chronic pain patients were significantly higher than healthy volunteers (P < .050).
Conclusion: The stimulus intensity should be individually adjusted to 2 ℃ above the patient’s pain thresholds to assess TSSP clearly.
Musculoskeletal pain is a cause of disability in older individuals and is commonly associated with executive function deficits. In particular, verbal fluency deficits have been previously reported in older individuals with and without musculoskeletal pain, however, no studies have examined non-verbal fluency. The present study investigated non-verbal fluency performance in younger and older individuals and associations with clinical and experimental pain. The NEPAL study included older (n = 63) and younger (n = 28) individuals who completed demographic, and clinical pain assessments followed by a multi-modal QST battery. A subset of participants (older n = 39/63, younger n = 11/28) underwent a structural 3T MRI to extract cortical thickness and subcortical gray matter volumes. The Ruff Figural Fluency Test was administered to assess fluid/divergent thinking, ability to shift cognitive set, and planning strategies. Total Unique Designs drawn and Error Ratio assessed participants' ability to minimize repetition while maximizing unique productions. Adjusting for race and education, older participants with chronic pain had significantly lower Total Unique Designs (67.1 ± 20.3) compared to older adults without chronic pain (78.8 ± 15.9) and younger controls (93.8 ± 20.3, p < 0.001). Within the older sample, those with chronic pain had a significantly greater Error Ratio (0.22 ± 0.3) compared to those without chronic pain (0.09 ± 0.06) and younger controls (0.05 ± 0.05, p = 0.002). In older participants, greater Total Unique Design scores were significantly associated only with lower pressure pain sensitivity (r = 0.300, p = 0.031) while greater Error Ratio scores were significantly associated with greater thermal pain sensitivity (r = 0.304, p = 0.027). However, after accounting for sleep quality, clinical and experimental pain associations were eliminated. Across all participants, non-verbal fluency performance was associated with cortical thickness in frontal, parietal and temporal regions as well as several subcortical gray matter structures even after adjusting for multiple comparisons (p's < 0.001). Our findings suggest a pain-related deficit in non-verbal fluency beyond the established age-related decrements that may be dependent on sleep quality and was associated with specific patterns of gray matter structure.
Overheated phones lead to uncomfortable user experience and degrade the reputation of the phone brand. This paper focused on the antecedents and consequences of mobile thermal satisfaction. The paper proposed the top influencing factors that affect the thermal satisfaction of mobile phones and emphasized the importance of mobile thermal performance in user experience and purchasing decision. A two-phase study was conducted. In phase I, 10 experts in human–computer interaction and phone engineering participated in a focus group study to obtain influencing factors of mobile thermal satisfaction. The experts highlighted the importance of thermal performance by ranking it with other key performance indexes of mobile phones. In phase II, 82 experienced phone users with gaming experience were interviewed on their thermal experience during daily phone usage. The user interviews provided key insights into how thermal satisfaction influenced user experience and indicated that thermal performance played an important role in purchasing decision of mobile phones.
Offset analgesia (OA) is the disproportionate decrease in pain experience following a slight decrease in noxious heat stimulus intensity. We tested whether sequential offsets would allow noxious temperatures to be reached with little or no perception of pain. Forty-eight participants continuously rated their pain experience during trials containing trains of heat stimuli delivered by Peltier thermode. Stimuli were adjusted through either stepwise sequential increases of 2°C and decreases of 1°C or direct step increases of 1°C up to a maximum of 46°C. Step durations (1, 2, 3, or 6 s) varied by trial. Pain ratings generally followed presented temperature, regardless of step condition or duration. For 6-s steps, OA was observed after each decrease, but the overall pain trajectory was unchanged. We found no evidence that sequential offsets could allow for little pain perception during noxious temperature presentation.
NEW & NOTEWORTHY Offset analgesia is the disproportionate decrease in pain experience following a slight decrease in noxious heat stimulus intensity. We tested whether sequential offsets would allow noxious temperatures to be reached with little or no perception of pain. We found little evidence of such overall analgesia. In contrast, we observed analgesic effects after each offset with long-duration stimuli, even with relatively low-temperature noxious stimuli.
Detection thresholds for Semmes-Weinstein monofilaments (SW tester), a 5-Hz rectangular electric stimulus and a warming stimulus were measured in the normal lower lip and chin area of 242 subjects (87 males, 155 females). Differences in terms of the stimulated region, gender and age were examined and the coefficients of variance (CVs) of the thresholds of subjects for the various stimuli were examined to determine the reliability of the measurements.
The lower lip was more sensitive than the chin area to all stimuli. The threshold for the automatically increased warming stimulus including reaction time was higher than that for a specific warming stimulus excluding the reaction time. The thresholds of the lower lip and chin area for all stimuli tended to be higher for elderly subjects than younger ones, except for the thermal threshold of the lower lip; the thermal threshold of the lower lip was found to be independent of age. The thresholds for the warming stimulus of the lower lip and chin area were independent of gender, whereas the thresholds for the SW tester of the lower lip and chin area appeared to be related to gender in subjects aged in their 30s to 60s. Moreover, the thresholds for the 5-Hz rectangular electric stimulus appeared to be related to gender in subjects in their teens to 40s. The CVs of the thresholds to the 5-Hz rectangular electric stimulus and warming stimulus were lower than those to the SW tester.
Detection thresholds to Semmes-Weinstein monofilaments, 5-Hz rectangular electric stimulation and warming were measured in 38 affected sides of neurosensory disturbance of the lower lip and chin after dental and oral surgery treatment. The ages of the patients ranged from 11 to 72 years. The examination periods were within 1, 6, 12 and 24 months after the nerve injury. The differences in recovery with time and measuring methods were examined. Improvement of sensation was more remarkable within 6 months after the nerve injury than from 6 to 12 months and 12 to 24 months. Though improvement was observed from 12 to 24 months after nerve injury, it was the least among the three periods. The cases with slightly higher threshold than that of the normal side improved within 12 months after the nerve injury. Improvement of the threshold for warm stimulation was slower than for the two other sensory tests throughout the investigation period.
The thermal sensory analyzer is an instrument employed for measuring the sensation capacity of individuals, basically stimulating the sensory nerve endings found on the skin, and assessing a person’s ability to feel warm and cold sensations, as well as warm pain and cold pain sensations, hence nociception as well. The thermal sensory analyzer (TSA) is used in experimentation belonging to a wider umbrella term called Quantitative Sensory Testing Technique (QST).
QST is a broader term used to describe testing techniques that researchers and physicians use in experiments to detect the health and relative function of the sensory nerves of individuals. QST involves testing with two types of machines: the first one, already mentioned, is the thermal sensory analyzer, which we discuss in more detail, and used to detect the threshold of thermal sensations such as warmth, cold, as well as pain sensation in the form of cold pain and warm pain. The other is the VSA-3000 (vibratory sensory analyzer), which tests vibratory sensation and can be coupled with the TSA-ii for thermal and pain assessment as well. VSA-3000 mainly tests for diabetic neuropathy, carpal tunnel syndrome, lumbar radiculopathies, peripheral and compression neuropathies, female sexual dysfunction, and erectile dysfunction.
The crux of Quantitative Sensory Testing Techniques is that it is a noninvasive, and thus patient friendly, way of testing peripheral sensation and can help diagnose early sensory deficits in diabetics and gage the recovery and progression of patients with other peripheral sensation disorders. Results obtained are compared to a standard of normal values which are also contained within the software of the machine.
It is well known that pain sensation exhibits physiological and psychological features and is influenced by many factors such as the strength of the noxious stimulus, state of the organism, and environmental variables. As engineers, we want to know the different features of skin thermal pain and how they are induced. This will be helpful for engineers to apply engineering methods to solve biological and neural problems. In this chapter we mainly discuss the physiological features of pain sensation, and psychological features are not included in this chapter.
Introduction: After spinal cord injury, contact heat evoked potentials (CHEPs) may represent a means to refine the clinical assessment of sensory function from each spinal cord segment by quantifying nociception, including conduction along the spinothalamic tract. Methods: The influence of stimulation site (i.e., dermatomes) on CHEPs and thermal thresholds in 19 healthy subjects (mean age, 45.2 +/- 18.3 years) divided into 2 age classes (younger subjects, n = 10; mean age, 28.8 +/- 5.2 years; older subjects, n = 9; mean age, 63.4 +/- 3.4 years) at 5 different dermatomes (C4, C5, C6, C8, and T4) was assessed. Results: In terms of distance from the body midline (i.e., spinal cord entry), there was a reduction in CHEP amplitudes from proximal (C4 and T4) to distal (C6 and C8) dermatomes with a corresponding reduction in nociceptive perception (i.e., pain threshold and rating). Within primary and secondary cortical sensory areas, including areas associated with affective noxious processing, the cortical source density analysis showed a similar current density distribution between C4 and C8 dermatomes but consistent higher current densities for C4. Conclusions: The study supports CHEPs as a feasible tool for assessing discrete dermatomes corresponding to spinal cord segments. The results suggest that the proximodistal pattern in the intensity of perceived pain and CHEP amplitudes is likely attributable to the distribution of heat nociceptors and the increase in conduction distance from proximal to distal dermatomes. The present findings emphasize on the importance that if patients are assessed segment by segment, the underlying topographical differences need to be accounted for.
Computer-assisted thermal threshold testing is a psychophysical semi-quantitative method of testing the function of small nerve fibres. At present, there is not enough data available on the effect of physiological variables on the threshold value and on the intra-individual variability of the test. Methods: Thermal threshold for heat and cold was determined in a group of 50 healthy volunteers (25 males and 25 females) in two localizations (thenar of the left upper extremity and dorsum of the right lower extremity). Each individual was examined with three different algorithms: two reaction time methods (reaction time inclusive - non-randomised and randomised variant of the Limits method) and one constant stimulus method (reaction time exclusive - randomised variant of the Levels method). To determine intra-individual variability, all tests were repeated in 30 individuals within one week and the upper normal limit of physiological intra-individual change of each test was determined. Results: Values of thermal threshold for cold decreased significantly whereas values for heat increased in examination of lower extremities, in men, and when using reaction time. The effect of age on thermal threshold was not significant. Intra-individual variability of threshold values expressed as the median of coefficients of intra-individual variability fell between 15 and 30% and was independent of test type, examined location, age or gender. Conclusions: Normal limits have to be determined with respect to gender, algorithm type and localization of the thermal element. Intra-individual variability of threshold values is acceptable, considering the psychophysical character of the test, is comparable to other quantitative tests of sensory perception and is not significantly influenced by test type or by physiological variables.
A tablet computer’s surface temperature can reach levels that can lead to user discomfort, especially in a warm environment. The ambient environments in which tablet computers are used can also vary. To understand how users perceive the heat from tablet computers, a laboratory study was conducted with controlled surface temperatures and ambient temperatures. A positive relationship between surface temperature and participants’ thermal sensation scores was found. Participants’ thermal responses to the surface heat of a simulated tablet were also moderated by the indoor temperature. Higher surface temperature (44°C) was rated less warm in cool environment than hot environment, while lower surface temperatures (34-38°C) were rated warmer in cool than hot environment. The thermal responses corresponding to the tablet surface temperatures and ambient temperatures will be helpful for setting future tablet computer heat dissipation design limits.
Measurement of cutaneous thermal thresholds is a valuable technique for detecting small fibre neuropathy. A robust and portable microcomputer controlled system, which separately measures thresholds for warming and cooling, is described. Thresholds at three sites have been measured; the cheek, the dorsum of the hand and the sole of the foot. Regional variability and a correlation with age have been found, indicating the sensitivity of this system.
Quantitative sensory testing (QST) is based on well-developed psychophysical methods that define not only the stimulus (type, characteristics, quantity, presentation, testing format, and environment) but also the response (form and analysis). With the availability of personal computers, transducers, electronic circuitry, and specially written software, it became possible to develop systems that delivered physical stimuli with waveforms that were precisely defined, quantitated, and graded over a broad range of magnitudes, and capable of eliciting unitary sensations. Specific algorithms of testing and finding threshold could now be programmed for exact and sequential error-free testing. Results could also be efficiently and accurately printed out and compared with normal values with consideration of modality, site, gender, height, and weight. QST's main application is in quantifying modality-specific detection thresholds (and some suprathresholds also) in health (by site, side, development, aging, and other) and in disease (involving sensory receptors, nerve fibers, central nervous system tracts, or cerebral association areas), allowing it to play the unique role of standardizing the clinical examination. Used to identify modality-specific sensory loss it can, for example, be correlated with the compound action potential of sural nerve in vitro and with the number and sizes of fibers. In detecting patterns of sensory abnormality, it can also suggest the presence of specific diseases and be used to follow the course of sensory loss. Finally, because it is the best approach to detect, characterize, and quantitate sensory abnormality, it is useful both in epidemiologic and controlled clinical trials. Although our review focuses especially on the approaches and system we have developed, other systems using standardized approaches are available allowing the evaluation of vibratory (VDT), cooling (CDT), and warming (WDT) detection thresholds and visual analog scaling of heat pain (HP VAS).
The distributions of sensory thresholds were estimated in a healthy population while controlling for potential covariates. Using the method of levels and the two-alternative forced choice, thermal and vibration thresholds respectively were measured in the hand and foot of 148 subjects. Age was uniformly distributed between 20 and 86 years. Independent effects of age, gender, height, and skin temperature were estimated using multiple linear regression. Parametric and nonparametric methods were used to estimate the distributions of interest. Significant age-related increases were observed for all vibration thresholds (P < 0.0001), and for thermal thresholds in the foot (P < 0.0002). Percentiles were estimated for thermal thresholds in the hand and age-adjusted continuous distributions were calculated for all other thresholds. Height was positively associated with vibration thresholds in the foot (P < 0.003), and appropriate corrections were made. Our results provide reference values for thermal and vibration sensory thresholds in a healthy population, allowing for the accurate diagnosis of disordered sensory function. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:367–374, 1998.
Quantitative sensory testing has become commonplace in clinical neurophysiology units. Measurement of the thermal and vibratory senses provides an estimate on function of sensory small and large fibers, respectively. Being psychophysical parameters, sensory threshold values are not objective, and various test algorithms have been developed aiming at optimized results. In this review the various test algorithms are screened, and their relative advantages and disadvantages are discussed. Considerations of quality control are reviewed, and the main fields of clinical application are described. © 1997 John Wiley & Sons, Inc. Muscle Nerve, 20, 198–204, 1997.
Quantitative sensory testing (QST) is commonly used in the assessment of diabetic neuropathy. However, little data are available on the reliability of tactile and thermal testing devices. Reproducibility of QST measures between centers has not been previously reported. This study was designed to validate QST testing procedures and determine if these devices are suitable for large scale multicenter clinical trials. Finger and toe vibratory (Vf, Vt) and thermal (Tf, Tt) thresholds were determined for ten normal individuals by a two-alternative forced-choice procedure using the Optacon Tactile Tester (OTT) and Thermal Sensitivity Tester (TST). Threshold measurements were reproducible between technologists and had a day-to-day coefficient of variation of Vf 20%, Vt 23%, Tf 41%, and Tt 95%. Thresholds were determined for 140 normal individuals at six centers. Mean threshold values between centers were not significantly different. Center-to-center coefficents of variation (CV) were Vf 44%, Vt 45%, Tf 47%, and Tt 87%. There was no significant difference in threshold measures with regard to sex, side studied, presence of calluses, or skin temperature. Vf thresholds significantly correlated with age (p < 0.01). There was no correlation between either vibratory or thermal thresholds in normal individuals, and nerve conduction velocities (NCV). Thermal and vibratory thresholds were determined for 98 diabetic patients. Diabetic subjects without clinical evidence of neuropathy were not significantly different from normal individuals, but diabetic patients with neuropathy had increased thresholds compared to normals (p < 0.05). We conclude that thermal and vibratory threshold testing with the OTT and TST yields reproducible measurements in normal individuals and provides an objective measure of clinical diabetic neuropathy that is well suited for multicenter trials.
A quantitative method for the examination of thermal sensibility was applied in 26 normal subjects and in patients with various neurological disorders. The stimulation technique resembled Békésy audiometry: the patient reversed the direction of the temperature change of a thermode whenever warm, cold, or thermal pain thresholds were reached. The resulting temperature curve enables a quantitative description of the subject's thermal sensibility and of the degree of impairment displayed by neurological patients.
Systems for automatic assessment of cutaneous touch-pressure, vibratory, and thermal sensation have been developed. These systems use stimuli which are quantified and reproducible, a two-alternative forced-choice technique, and programmed steps to test, score, and report. If normal responses from series of healthy persons have been measured, percentile values specific for test, site, age, and sex can be determined. Abnormality, as in neurological disease, can then be defined as the response which has a value greater than that of the 95th (or other) percentile. These systems may be used to detect and validate abnormalities of sensation in neurological disease and in persons at risk from new medications or from industrial toxins, and to monitor worsening or improvement of sensation in follow-up of a patient or in evaluation of therapeutic regimens.
1. Effects of rate of rise of temperature stimuli applied to skin on (i) unitary receptor threshold and frequency response often single C nociceptors, and (ii) on magnitude and reaction times of evoked pain were studied in fifteen healthy human volunteers. 2. Temperature ramps of 32 to 45 or 47 degrees C were applied at three consistent rates of rise to receptive fields of C nociceptors in dorsum of foot (n = 9) or hand (n = 1). For rates of rise of 0.3, 2.0 and 6.0 degrees C/s, mean receptor threshold for heat was remarkably uniform: 41.5 +/- 0.57, 41.5 +/- 0.61 and 41.9 +/- 0.71 degrees C respectively. 3. The mean discharge rate of the ten cutaneous C nociceptors increased with rate of rise of temperature stimuli: 1.22 +/- 0.13, 4.57 +/- 0.49 and 13.45 +/- 0.71 impulses/s, respectively, for stimulus temperature rates of 0.3, 2.0 and 6.0 degrees C/s. 4. Magnitude estimates of pain for thirteen subjects also increased with rate of rise of temperature stimuli. Mean normalized magnitude estimates of heat pain were: 11.8 +/- 1.55, 15.1 +/- 0.84 and 28.0 +/- 1.87 for stimulus rates of rise of 0.3, 2.0 and 6.0 degrees C/s, respectively. 5. Results of simultaneous recordings of reaction time for pain and of C nociceptor responses to heat ramps given at 2.0 degrees C/s, in three subjects, indicate that under those circumstances heat pain messages are exclusively mediated by C nociceptors.
The quantitative somatosensory thermotest (QST) assesses the function of afferent channels concerned with sensory submodalities served by small calibre fibres. Measured ramps of ascending or descending temperature are applied to the skin through a Peltier contact thermode, and detection thresholds are recorded as the subject signals the onset of a particular sensation.
The present study describes underlying principles, methodological aspects and normal reference values for the QST. In patients, measurement of thresholds for cold sensation, warm sensation, cold-induced pain and heat-induced pain, applied to 465 individuals, yielded 13 abnormal patterns segregated into three main groups: (i) thermal (cold or warm) hypoaesthesia; (ii) thermal hyperalgesia (abnormally reduced threshold for cold and/or heat induced pain); (iii) thermal hypoaesthesia combined with thermal hyperalgesia.
Critical analysis of these results yielded a number of observations of general relevance: (i) thermal specific (warm or cold) hypoaesthesia and thermal (heat or cold) hyperalgesia may occur in the absence of hypoaesthesia for tactile submodalities served by large calibre afferents; (ii) cold hypoaesthesia and warm hypoaesthesia may dissociate from each other; (iii) thermal pain hyperalgesias may occur in the absence of hypoaesthesias for specific cold or warm sensations; (iv) cold hyperalgesia and heat hyperalgesia may dissociate from each other.
Thus, a negative routine sensory examination and unimpaired sensory nerve action potentials do not exclude possible somatosensory dysfunction. Furthermore, while most methods of sensory testing only document normality or deficit, the QST permits additional documentation of hyperalgesia, a positive sensory phenomenon that implies unusual pathophysiologies such as sensitization of receptors, central hyper-excitability, disinhibition or, possibly, ectopic nerve impulse discharge.
This psychophysical test does not specify the level within afferent channels, between skin and brain-mind, where the abnormality resides. It is recommended that the QST for all four thermal specific and thermal pain functions be incorporated in routine neurological assessment.
Small and large fibre neuropathy are common findings in patients with long-standing diabetes mellitus. The Thermal Threshold Tester was tested to obtain normal values for thermal perception threshold for warmth and cold. This device produces thermal stimuli by means of a Peltier element placed on the skin. Warm and cold thresholds are measured using a forced choice method with an up-and-down-transform rule and expressed in degrees Celsius (degree C). Thresholds were measured at the right wrist and right foot in 80 normal subjects, divided into four age groups; 25-34, 35-44, 45-54, and 55-65 years. The repeatability coefficient was assessed by twice measuring 39 diabetic patients without known neuropathy. Warm thermal threshold in the hand showed a significant increase with age from 0.09 +/- 0.5 (mean +/- SD) in the youngest age group to 0.17 +/- 0.08 degree C (p less than 0.05) in the oldest age group. Cold thermal threshold in the hand (varying between 0.08 +/- 0.04 and 0.14 +/- 0.05 degree C) and warm thermal threshold in the foot (varying between 2.45 +/- 1.93 and 4.06 +/- 2.57 degrees C) did not differ significantly between the four age groups. There was a significant increase in cold thermal threshold in the foot with age, increasing from 0.31 +/- 0.24 to 0.56 +/- 0.44 degree C (p less than 0.05). Reproducibility in the diabetic subjects was good for measurements of warm and cold threshold in the hand, but poor for warm threshold in the foot in the normal range and for cold thermal threshold in the abnormal range.
Perception thresholds for warm and cold sensation were measured by two methods, the method of levels and the method of limits, at various rates of temperature change. The following findings were obtained. (1) The threshold value is critically dependent upon the method through which it is obtained, being higher for the method that includes reaction time in the measurement. (2) When using a method that includes participation of reaction time, threshold increases with increasing rate of temperature change. (3) The artefactual threshold elevation recorded through the method of limits corresponds precisely to the reaction time. (4) Conduction velocities for the primary afferents mediating the sensations of warm and cold, calculated on the basis of reaction time and conduction distance are in keeping with the mediation of warm sensation by unmyelinated primary afferents and of cold sensation by small myelinated afferents. (5) Measurement of threshold by the method of levels and direct measurement of reaction time enables calculation of conduction velocity for the specific sensory submodality tested from a single stimulation site.
Thermal testing was carried out on 55 healthy subjects in order to establish normal results and reproducibility of warm and cold thresholds. Diurnal variations of thresholds were investigated in a further 30 normal subjects. Then the sensitivity of different testing procedures was investigated in 33 patients with diabetes mellitus, but without severe polyneuropathy. Forced choice testing takes 6 times longer than the method of limits, and the results are not considerably different. It is thought that the forced choice algorithm does not provide a method for clinical routine. Another new approach, the double random staircase method, may help to exclude bias without taking too much time.
Cutaneous thresholds for vibration and thermal sensitivity were quantitated at the index finger and great toe in 54 subjects without obvious neurological disease. Twelve patients over sixty years of age also consented to standard nerve conduction studies which proved normal. Vibration thresholds progressively increased with age to a significant degree at the finger (p less than 0.05), and especially at the toe (p less than 0.001). Thermal sensitivity thresholds showed no significant relationship with age. These findings confirm the clinical notion that vibration discrimination decreases with normal aging, especially in the toes.
The conventional estimation of motor, sensory, and mixed nerve conduction velocities reflects activity in the fastest conducting, heavily myelinated nerve fibers that are only a small proportion of the total. Unmyelinated and thinly myelinated fibers are not evaluated by this technique and numerically represent the largest group of fibers in human cutaneous nerves. The availability of new quantitative techniques to study this aspect of sensory function is an important addition to standard electrodiagnosis. Patient understanding and cooperation is essential because subjective responses are evaluated. We evaluated a reference range for 20 healthy subjects as well as variability on repeated testing. Vibration and thermal thresholds were measured bilaterally at several sites. Measurements were repeated at intervals ranging from two days to three months. There was no side difference but substantial site differences were noted for all measurements. Intraindividual variation was substantial but within the expected range for a psychophysiologic test. Close correlation was noted between various measurements at same and different sites, indicating a great degree of interindividual variation. The Marstock method is recommended for routine clinical use.
Afferent impulse frequency, one of the determinants of subjective magnitude of sensation, varies with the rate of rise of stimulus intensity: the faster the increase in stimulus energy, the higher the frequency of firing for a given amount of energy. This predicts that the steeper the stimulus ramp the lower will be the threshold for perception. While such inverse relation holds for myelinated fibre mediated cold sensation and mechanical pressure sensation, the opposite has been reported for unmyelinated fibre mediated heat pain and cold pain sensations. These paradoxical results intuitively suggest possible reaction time artefact. Indeed, a fixed time interval that includes conduction of the impulses to the brain, central processing and efferent conduction, intervenes between sufficient peripheral stimulus and the voluntary signal in reaction to subjective experience. As stimulus temperature continues to rise along this time, an artefactually high threshold reading results: the steeper the temperature rise, the larger will be the artefact, particularly for submodalities with longer reaction time. The present study compared heat pain threshold, obtained through a method that involves reaction time participation, with heat pain thresholds obtained bypassing reaction time. It was found in 16 volunteers that: (a) Heat pain thresholds decreased as the rate of temperature rise increased when reaction time was not a factor (P less than 0.001). (b) Heat pain thresholds determined through the method involving reaction time participation were significantly higher than those obtained bypassing reaction time (P less than 0.01). Such difference increased with increasing rates of temperature rise. (c) Peripheral conduction velocity calculated from average reaction time was found to be approximately 0.6 m/sec.(ABSTRACT TRUNCATED AT 250 WORDS)
We have studied characteristics of subjects that could potentially influence quantitative sensory measurements in 156 non-neuropathic individuals. All subjects had measurements of vibration perception at the hallux and index finger with the vibration sensitivity tester and measurements of cool and warm perception at the hallux with the thermal sensitivity tester. Age, height, and skin temperature were all inversely related (P less than 0.05) to vibration sensitivity at the hallux, while age was inversely related (P less than 0.01) to vibration sensitivity at the index finger. In multiple regression analyses the significant associations persisted (P less than 0.01). Neither cigarette smoking nor the occasional use of alcohol were related to the quantitative sensory indices. These data indicate that age, height, and skin temperature should be considered in the assessment of vibration perception and that thermal sensitivity is relatively resistant to these factors.
To evaluate cold and warmth cutaneous sensation separately, thermal discrimination thresholds (TDTs) for the foot were estimated for cold and warm stimuli in 71 normal subjects aged between 21 and 92 years. A "thermoaesthesiometer" operating on the Peltier principle was used. A rise of TDTs with age was found. Furthermore, female subjects appeared to have lower thresholds than males. Independent of age or gender, TDTs for cold stimuli were on average lower than for warm stimuli. In accordance with other studies, a large intraindividual variability was found, which emphasizes the necessity for repeated measurements.
Thermal thresholds can be measured psychophysically using either the method of limits or a forced-choice method. We have compared the two methods in 367 diabetic patients, 128 with symptomatic neuropathy. The Sensortek method was chosen for the forced-choice device, the Somedic modification of the Marstock method for a method of limits. Cooling and heat pain thresholds were also measured using the Marstock method. Somedic thermal thresholds increase with age in normal subjects, but not to a clinically significant degree. In diabetics Marstock warm threshold increased by 0.8 degrees C/decade, Sensortek by 0.1 degrees C/decade. Both methods had a high coefficient of variation in normal subjects (Sensortek 29%, Marstock warm 14%, cool 42%). The prevalence of abnormal thresholds was similar for both methods (28-32%), though Marstock heat pain thresholds were less frequently abnormal (18%). Only 15-18% of patients had abnormal results in both tests. Sensortek thresholds were significantly lower on repeat testing, and all thresholds were higher in symptomatic patients. Both methods are suitable for clinical thermal testing, though the method of limits is quicker. In screening studies the choice of a suitable apparatus need not be determined by the psychophysical basis of the test.
Three experiments evaluated the reliability and sensitivity of an interactive multiple random staircase (MRS) assessment of painful thermocutaneous sensations. One hundred and sixteen subjects used a 4-point category scale (no pain, mild, moderate, intense) to rate the intensity of sensations produced by 3-sec thermal stimuli applied to the volar forearm at 20-sec intervals by a 1-cm diameter contact thermode. Each of the 3 intervals between the 4 verbal responses was defined as a boundary. A pair of staircases was associated with each boundary. On each trial, 1 of the 6 staircases was chosen randomly and the stimulus intensity indicated by that staircase presented. The response to that stimulus determined the intensity presented by that staircase the next time it was randomly selected. Responses above the associated boundary decreased stimulus intensity, responses below the associated boundary increased stimulus intensity. In the first experiment, 1 staircase from each of the 3 boundaries began at 43 degrees C and 1 began at 48 degrees C. Staircases for each boundary converged to within 0.3 degree C after 12 trials/staircase. The sensitivity of the method to a narcotic analgesic was assessed by open (exp. II) and double-blind (exp. III) intravenous infusion of 1.1 micrograms/kg fentanyl. Administration of fentanyl increased staircase temperatures, indicating that these higher temperatures were now required to elicit the same verbal responses. This shift in temperature reached a peak effect 11 min after fentanyl administration. These results suggest that this method provides a reliable measure of sensory magnitude in units of stimulus intensity. It does not require assumptions about psychological units of pain.(ABSTRACT TRUNCATED AT 250 WORDS)
The effect of stimulus area and adaptation temperature on warm and heat pain threshold were studied in healthy human subjects using a contact thermal stimulator. The stimulus area was varied in the range of 1.3 to 11.8 cm. Both the warm and heat pain thresholds decreased with increasing stimulus surface. Heat pain and warm thresholds were equally affected by the stimulus surface. The adapting temperature was varied in the range 25-35 degrees C, and warm thresholds were elevated with increasing adaptation temperature. The change of heat pain thresholds with increasing adapting temperature was not significant. Thus, there are both differences and similarities concerning how the different stimulus conditions affect heat pain and warm thresholds.
We have examined associations between height and quantitative sensory, nerve-conduction, and clinical indices of diabetic peripheral neuropathy in adult diabetic patients. Vibratory sensitivity was strongly related to height when measurements were made with either the vibration sensitivity tester (P = .02) or the biothesiometer (P less than .01); however, there was no relation between thermal sensitivity (as measured with the thermal sensitivity tester) and height. The peroneal and posterior tibial motor nerve-conduction velocities were inversely related to height (P less than .05 for both). When age and diabetes duration were included as variables in multiple regression analyses, the associations with height became stronger. Clinical indices of peripheral neuropathy were also related to height in these analyses. Glycosylated hemoglobin was significantly related to thermal sensitivity and the peroneal and posterior tibial motor nerve-conduction velocities but not to vibratory sensitivity. These data indicate that height has a marked influence on quantitative sensory, nerve-conduction, and clinical indices of diabetic peripheral neuropathy.
Thermal tests were performed in 117 healthy subjects on the face, wrist and leg; 32 were tested on the legs with different rates of cooling and warming. Additionally 2 groups of diabetics (37 patients) were tested. Thermotesting was most sensitive on the legs using a rate of temperature change of 2.5-2.8 oC/s. Warm and cold perception should be tested separately. Cold perception testing is most sensitive. Combined tests of warm and cold thresholds as well as the testing of cool pain and heat pain do not improve results. Abnormal cold perception may be an early indicator of diabetic small fibre polyneuropathy, leading to cold trauma and ulcers on the feet.
Absolute thresholds were measured on 27 young (ages 19 to 31) and 21 elderly (ages 55 to 84) humans to six modes of cutaneous
stimulation (single ramp-and-hold skin indentations — tactile, vibration at 40 and 250 hz, temperature increases and decreases,
and noxious heat) at two sites, the thenar eminence and the plantar foot. Comparisons of the elderly and young groups showed
that elderly persons were significantly, p =s .001, less sensitive than young individuals to mechanical stimuli (tactile and
vibration) at both sites. No significant differences were found in thresholds to thermal stimuli (warm-, cold-, and heat-pain)
at either site except elderly feet were significantly, p =s .001, less sensitive than young feet to warm stimuli. Thresholds
of elderly individuals were compared with the young group thresholds for deficits in sensitivity. All elderly participants
showed deficits to one or more of the stimulus modes at one or the other site. There were significantly, p =£ 0.01, more deficits
to mechanical than to thermal stimuli. There was no increase in the frequency of deficits with increasing age
The Thermal Sensitivity Tester (TST) is a portable device designed to quantify the ability to discriminate small differences in temperature at the distal extremities of the hands and feet. The testing surfaces are two identical nickel-coated copper plates, which can be set and maintained over a wide range of temperature levels. The threshold for detecting the colder surface is determined using a two-alternative, forced-choice algorithm. The mean threshold in the normal population is 0.67 degree C and 1.01 degree C for the index finger and great toe, respectively. The TST is especially useful in diabetic neuropathy and for rapid screening of large populations under field conditions.
Clinical tests of thermal sensation are poorly quantified and not strictly modality specific. Previous automated thermal testing systems have had limited usefulness with high intra-and inter-individual variability. This paper describes an automated thermal system (Glasgow system) which is an extensive modification of previous techniques to answer these criticisms. It comprises a microprocessor-driven Peltier element and utilises the forced choice method of psychophysical analysis to determine the thresholds to thermal stimulation. In a control group of 106 healthy subjects the mean heat threshold for the wrist was found to be 0.23 degree C (SD = 0.06 degree C) and the mean cold threshold 0.15 degree C (SD = 0.05 degree C). Repeated determinations showed a maximum of 5% intra-individual variation in comparison to previously reported values of up to 150%.
Using two identical thermostimulators which operated on the Peltier principle, thermal cutaneous sensation of the hand and the foot was investigated in 36 normal subjects and in 20 patients with diabetic neuropathy. Using a two-alternative forced-choice testing procedure, thermal discrimination thresholds were determined twice. The values found in normal subjects are comparable with data from the literature. It was confirmed that thermal discrimination of the foot decreased with increasing age. In patients with diabetic neuropathy the increased thresholds for the foot could be correlated with length-dependent degeneration of small nerve fibres.
Measurement of thresholds for heat-induced pain was performed on 106 normal subjects, at thenar eminence and foot dorsum, using the reaction time-inclusive method of limits. Tests were repeated 2 weeks following the first test for most of the subjects. After determination that there were no outlying data points and that there was no systematic relationship between magnitude and variability of test scores, data from between 72 and 76 subjects were used to define normal upper and lower ranges by age, as well as repeatability coefficients. This was done through ANOVA-based procedures that extend standard repeatability assessment methods. Normative data tables are presented, with measures of repeatability for the various sites and modalities. For the conventional test range, reaching 55 degrees C, measurement of heat pain thresholds can define both hyper- and hypoalgesia. Application of repeatability coefficients allows for intra-individual inter-session comparison in longitudinal studies.
The use of different paradigms and initial skin and thermode reference temperatures in quantitative thermal testing does not allow strict comparison of results generated from different laboratories. We tested (a) whether the reproducibility of the method of limits is higher for measurement of isolated warm and cold thresholds (WT, CT) as compared to difference limen (DL) thresholds, i.e. values derived from alternating warm and cold stimulation, and (b) whether WT-, CT- and DL-thresholds depend on the value of baseline skin and thermode temperatures. In 20 healthy volunteers WT-, CT-, and DL-thresholds were determined at the volar wrist using a Somedic-Thermotest. In condition A the baseline thermode temperature was set at 30 degrees C, and in conditions B and C at 35 degrees C; in condition C the tested skin area was also warmed to 35 degrees C prior to the test. The randomized tests were repeated within 1-8 days. WT-, CT-, and DL-values were reproducible, but DL-values were more widely spread than WT and CT. CT variability was lowest in condition A, and WT variability in condition C. We conclude that DL determination should be abandoned, since CT and WT better differentiate normal from abnormal thresholds than the coarse DL-values. We recommend the use of the lower baseline thermode temperature (30 degrees C) and elimination of warming of the tested skin area prior to the test.
Sensory threshold measurements are criticized as subjective and therefore not to be relied upon in clinical diagnostic practice, particularly when deliberate deception by the patient is suspected. In an attempt to devise a method which permits dependable sensory threshold interpretation, individual variability of thresholds was examined in normal and neuropathic subjects. Normals were also instructed to feign sensory impairment resulting from hypothetical injury. For each subject, a number of threshold readings were averaged, yielding individual means and variances. Feigning normal subjects evidenced a larger variance compared to trustworthy normal and neuropathic subjects. Thus, alertness to variance reinforces the psychophysical analysis: small variance values suggest trustworthy normal or pathological results, whereas large variance calls the interpreter's attention to feigned results or inattentive test performance.
Measurement of thresholds for warm and cold sensation was performed on 106 normal subjects, at thenar eminence and foot dorsum. Three test algorithms were used, the reaction-time-inclusive method of limits, and reaction-time-exclusive methods of levels and staircase. Tests were repeated 2 weeks following the first for most of the subjects, and after elimination of 5 outlying subject data points, and determination of no systematic relationship between magnitude and variability of test scores, data from between 72 and 76 subjects were used to derive repeatability coefficients, by ANOVA-based procedures which extend standard repeatability assessment methods. Normative data tables are presented, with measures of repeatability for the various algorithms and modalities. Method of limits tests exhibited inter-session bias, and large repeatability coefficients, compared with methods of levels and staircase, which exhibited no bias and had better (lower) repeatability coefficients. All three methods had similar test durations. We conclude that on the basis of these data, the reaction-time-exclusive methods of levels and staircase have a definite advantage over the method of limits.
To evaluate the test-retest reproducibility of vibratory perception (VPT) and thermal discrimination (TDT) thresholds on the foot in older adults, we examined 20 50-76-year-old subjects with, and 19 without non-insulin-dependent diabetes mellitus. Adjusted reference values for both thresholds were obtained by assessing the relations with age, body height, and sex among 216 subjects with normal glucose tolerance, of the same age, sampled randomly from a geographically defined general population. The VPT appeared to be more reproducible than the TDT (reliability coefficient 0.89 vs. 0.54). The reproducibility of the VPT was inversely related to age and better for men than for women. Diabetes and glycemic level did not affect the reproducibility of either threshold. Both thresholds were related to age and height. Women had a higher VPT than men. The relations between sex and sensory thresholds at the lower limb, reported in previous studies, were probably confounded by height.
A systematic investigation of covariates of quantitative sensory thresholds was performed on data collected by the U.S. Centers for Disease Control. Vibrotactile and thermal sensory thresholds were obtained from the index finger and great toe of 4,462 male Vietnam-era veterans. The magnitude of effect of skin temperature, height, body mass index, age, race, place of military service, smoking status, alcohol consumption, income, and examiner was estimated for the four outcomes. The major covariates of finger and toe vibrotactile threshold were age, height, body mass index, and examiner. The major covariates of toe thermal threshold were height, income, and examiner, and of finger thermal threshold were age, income, examiner, race, and smoking status. Alcohol consumption had only small effects on vibrotactile thresholds and essentially no effect on thermal thresholds. These results provide an empirical basis for selecting variables to control in studies employing vibrotactile and thermal threshold measures.
In quantitative sensory testing, certain methods may lead to incorrect estimates of vibratory (VDT), cool (CDT), or warm (WDT) detection thresholds. We have shown that the specific forced-choice algorithm of testing employed in our Computer-Assisted Sensory Examination (CASE IV) system, when compared with other tests of nerve dysfunction, provides accurate and reproducible estimates of these thresholds. Because this forced-choice algorithm is time consuming and performance might be made worse by drowsiness or boredom, we explored other algorithms that might provide estimates of threshold similar to those obtained with the forced-choice algorithm, but more quickly. In a trial of 25 healthy subjects and 25 patients with neuropathy, the 4, 2, and 1 stepping algorithm with null stimuli, based in part on comparative data from computer simulation and insights from patient decision making, provides an accurate estimate of threshold. On average, the time needed for forced-choice testing was 12.8 +/- 2.9 minutes (mean +/- SD). For 4, 2, and 1 stepping testing, it was 2.7 +/- 2.5 minutes--a large saving of time. Since null stimuli were employed in the 4, 2, and 1 stepping algorithm, it was possible to monitor for spurious responses and repeat the test if they occurred at an excessive rate. The algorithm appears to be sufficiently robust to be recommended for clinical use and for some controlled clinical and epidemiologic trials.
We recently found that vibratory detection threshold is greatly influenced by the algorithm of testing. Here, we study the influence of stimulus characteristics and algorithm of testing and estimating threshold on cool (CDT), warm (WDT), and heat-pain (HPDT) detection thresholds. We show that continuously decreasing (for CDT) or increasing (for WDT) thermode temperature to the point at which cooling or warming is perceived and signaled by depressing a response key ("appearance" threshold) overestimates threshold with rapid rates of thermal change. The mean of the appearance and disappearance thresholds also does not perform well for insensitive sites and patients. Pyramidal (or flat-topped pyramidal) stimuli ranging in magnitude, in 25 steps, from near skin temperature to 9 degrees C for 10 seconds (for CDT), from near skin temperature to 45 degrees C for 10 seconds (for WDT), and from near skin temperature to 49 degrees C for 10 seconds (for HPDT) provide ideal stimuli for use in several algorithms of testing and estimating threshold. Near threshold, only the initial direction of thermal change from skin temperature is perceived, and not its return to baseline. Use of steps of stimulus intensity allows the subject or patient to take the needed time to decide whether the stimulus was felt or not (in 4, 2, and 1 stepping algorithms), or whether it occurred in stimulus interval 1 or 2 (in two-alternative forced-choice testing). Thermal thresholds were generally significantly lower with a large (10 cm2) than with a small (2.7 cm2) thermode.(ABSTRACT TRUNCATED AT 250 WORDS)
Quantitative Thermotesting evaluates peripheral small nerve fiber function. The method of limits is a widely used algorithm of perception threshold determination. Normative data are needed to apply the method of limits in children and juveniles. In 225 healthy boys and girls, aged 7 to 17.9 years, warm and cold perception thresholds were established with the method of limits at the volar distal forearm, the thenar eminence, the lower medial calf, the lateral dorsal foot, and the cheek. A 1 degree C/s stimulus velocity, a 32 degrees C thermode baseline, and a 1.5-cm x 2.5-cm Thermotest stimulator were used. Accuracy of stimulus perception was studied by comparing the lowest to the highest response of five consecutive stimuli. The influence of different stimulator sizes on thresholds was tested at the lower calf and distal forearm with an additional 2.5-cm x 5.0-cm thermode. To determine the impact of the pretest skin temperature on thresholds, skin temperature was correlated with thresholds. Results showed good intratrial reproducibility of thresholds. The large thermode yielded lower thresholds than the small probe. Skin temperature had only minor influence on thresholds. The large probe should be used at body sites where it adjusts planely.
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