The association between health-related quality of life and noise or light sensitivity in survivors of a mild traumatic brain injury

Abstract

Purpose
Sensory impairment is a common aftereffect of mild traumatic brain injury (TBI); however, their influence upon treatment outcomes and quality of life has yet to be investigated. This study sought to determine the effects of noise and light sensitivity upon the quality of life of individuals diagnosed with a TBI.

Methods
A cross-sectional adult sample obtained from a longitudinal study (n = 293) provided measures of light and noise sensitivity and quality of life 12 months post injury. Sensitivities were taken from the Rivermead Post-concussion Symptoms Questionnaire, while quality of life was estimated using the Short-Form 36 health survey (SF-36).

Results
Approximately 42% of participants reported ongoing difficulties with noise and light sensitivity. Additionally, those reporting sensory difficulties also reported lower SF-36 domain and composite scores compared to those reporting no such symptoms. After controlling for known co-factors, hierarchical multiple regression analyses indicated that the combination of light and noise sensitivity explained between 8 and 35% of the variance in SF-36 scores.

Conclusions
Light and noise sensitivity appear to degrade the quality of life of those with a mild TBI. Our findings challenge contemporary rehabilitation practices that tend to sideline sensory complaints and instead focus on the remediation of acute TBI symptoms.

Full text

Vol.:(0123456789)
1 3
Quality of Life Research
https://doi.org/10.1007/s11136-019-02346-y
The association betweenhealth‑related quality oflife andnoise
orlight sensitivity insurvivors ofamild traumatic brain injury
DanielShepherd1 · JasonLandon1· MathewKalloor1· SuzanneBarker‑Collo2· NicolaStarkey3· KellyJones4·
ShanthiAmeratunga5· AliceTheadom1on behalf of BIONIC Research Group
Accepted: 21 October 2019
© Springer Nature Switzerland AG 2019
Abstract
Purpose Sensory impairment is a common aftereffect of mild traumatic brain injury (TBI); however, their influence upon
treatment outcomes and quality of life has yet to be investigated. This study sought to determine the effects of noise and light
sensitivity upon the quality of life of individuals diagnosed with a TBI.
Methods A cross-sectional adult sample obtained from a longitudinal study (n = 293) provided measures of light and noise
sensitivity and quality of life 12 months post injury. Sensitivities were taken from the Rivermead Post-concussion Symptoms
Questionnaire, while quality of life was estimated using the Short-Form 36 health survey (SF-36).
Results Approximately 42% of participants reported ongoing difficulties with noise and light sensitivity. Additionally, those
reporting sensory difficulties also reported lower SF-36 domain and composite scores compared to those reporting no such
symptoms. After controlling for known co-factors, hierarchical multiple regression analyses indicated that the combination
of light and noise sensitivity explained between 8 and 35% of the variance in SF-36 scores.
Conclusions Light and noise sensitivity appear to degrade the quality of life of those with a mild TBI. Our findings chal-
lenge contemporary rehabilitation practices that tend to sideline sensory complaints and instead focus on the remediation
of acute TBI symptoms.
Keywords Health-related quality of life· Brain injury· Noise sensitivity· Light sensitivity
Introduction
The economic, social, and personal costs of mild traumatic
brain injury (mTBI) have been well documented in the medi-
cal literature. Given a predicted 69 million new incidences
of TBI occurring each year [1], mTBI is set to become one
of the dominant disease burdens by 2020 [2]. Diagnosti-
cally, brain injuries are considered mild when the individual
affected remains conscious or loses consciousness for less
than 30min, and has no post-traumatic amnesia or disori-
entation after 24h of the mTBI-inducing event. Following a
mTBI, people typically report a variety of symptoms that, if
experienced chronically, form the diagnostic framework of
post-concussion syndrome. These mTBI-related symptoms
include headaches, dizziness, nausea, anxiety, depression,
and cognitive deficits. For many, these post-concussion
symptoms resolve within 1–4 weeks post injury, though for
up to 50% of individuals the symptoms endure and a diag-
nosis of post-concussion syndrome may be conferred [3, 4].
As part of post-concussion syndrome, sensory dysfunc-
tion is commonly a long-term sequelae of mTBI, though
sensory deficits have attracted comparatively little attention
in the literature, possibly because they are thought to be
the least salient of the acute mTBI symptoms [5]. While
chemosensory (e.g. gustation and olfaction) and vestibular
deficits are known to occur in patients with mTBI, it is the
* Daniel Shepherd
daniel.shepherd@aut.ac.nz
1 Department ofPsychology, Auckland University
ofTechnology, Private Bag 92006, Auckland1142,
NewZealand
2 School ofPsychology, The University ofAuckland,
Auckland, NewZealand
3 School ofPsychology, The University ofWaikato, Hamilton,
NewZealand
4 School ofPublic Health, Auckland University ofTechnology,
Private Bag 92006, Auckland1142, NewZealand
5 School ofPopulation Health, The University ofAuckland,
Auckland, NewZealand

Quality of Life Research
1 3
‘dual sensitivity impairment’ of noise and light sensitivity
that need to be the focus of clinical assessments of post-
concussive symptoms, as these can have a substantial influ-
ence on long-term recovery [6]. However, neither of these
sensory deficits are diagnosed with the aid of standardised
assessment protocols. Instead, practitioners rely on subjec-
tive reports from clinical interviews or post-concussion
inventories such as the Rivermead Post-concussion Symp-
toms Questionnaire (RPQ) [7]. In the environmental health
sciences, broad definitions of sensory sensitivity exist, and
in the clinical literature the inconsistent use of nomenclature
and unstandardised terminology makes comparisons across
studies fraught [6]. Generally, however, noise sensitivity has
been defined as personality factors or biological states that
amplify negative reactions to ambient sound [8], while light
sensitivity is characterised by mild-to-severe visual discom-
fort occurring in everyday light conditions [9].
The prevalence of debilitating sensory sensitivity in the
mTBI population has yet to be accurately estimated, though
in the general population the prevalence of light sensitiv-
ity is estimated at 10% [10], while high noise sensitivity
is reported by approximately 15% of adults and does not
appear to differ across residential context [11]. In mTBI pop-
ulations, Kashluba etal. [12] reported that at 3 months post
mTBI, 35% of patients reported noise sensitivity, and 29%
light sensitivity. Comparing sensory sensitivity at one and
12 months post mTBI, Dikmen etal. [13] reported that noise
sensitivity decreased from 27 to 22%, and light sensitivity
from 21 to 14%. These studies suggest that rates of noise
sensitivity are above those found in the general population,
and studies involving combat veterans suggest even higher
rates of noise and light sensitivity due to blast-related events
[14]. Recently, studies have begun to highlight the impor-
tance of sensory sensitivities as markers of mTBI recovery
trajectories. For example, in one longitudinal study of mTBI,
noise sensitivity was found to be the dominant predictor of
prolonged post-concussive symptoms [15]. While others
also report that noise sensitivity is a significant risk factor
for post-concussive symptoms [16], it may be less predictive
than light sensitivity [17]. More recently, in a New Zealand
sample of individuals with mTBI, higher levels of noise sen-
sitivity were linked to longer treatment and rehabilitation
times post TBI [3].
Health-related quality of life (HRQOL) measures are
commonly used as patient-centred assessment of functional
impairment post TBI. A systematic review of the well-vali-
dated Short-Form 36 (SF-36) HRQOL instrument indicated
that mTBI predominantly impacted physical, emotional, and
social functioning domains [18]. Noise exposure [19] and
noise sensitivity [20] have been shown to negatively impact
the HRQOL of the general population. Qualitative studies
into the experiences of mTBI and post-concussive symp-
toms have concluded that noise sensitivity is a debilitating
symptom [21] that can profoundly affect everyday function
and is often downplayed by clinicians [22–24]. Surpris-
ingly, few studies have directly compared post-concussive
symptoms and HRQOL measures in patients with mTBI.
One study showed a negative correlation between the total
number of post-concussive symptoms and SF-36 domain
scores; however, the relationships between individual symp-
toms and the SF-36 domains were not reported [25]. Only
recently have Voormolen etal. [26] reported the relationship
between the noise and light sensitivity subscales of the Riv-
ermead post-concussion symptoms inventory, indicating that
all correlations were negative and significant at the p < .001
level, though without directly reporting the coefficient values
themselves.
Sensory sensitivity within mTBI has been described as an
emerging challenge to professionals, and that the identifica-
tion of sensory impairment during the acute stage of mTBI
is imperative for best-practice rehabilitation and patient
quality of life [14]. The enduring impact of sensory-related
post-concussive symptoms upon HRQOL has received lit-
tle attention in the literature, and compared to other symp-
toms remains relatively unexplored [6]. It is evident that
more data are required to elucidate the relationship between
sensory sensitivities and HRQOL, and to establish if noise
and light sensitivities are clinically relevant. For many with
mTBI, post-concussive symptoms resolve quickly, and so
we chose to look at the long-term impact of noise and light
sensitivity upon HRQOL, with both measured at a 12-month
post-injury follow-up point. As such, the aim of the current
study is to determine whether light and noise sensitivity rat-
ings 12months post TBI can explain changes in HRQOL
beyond that explained by typical covariates such as gender
and age.
Methods
Participants
Participants were the 293 adults partaking in the 12-month
follow-up phase of the ‘Brain Injury Incidence and Out-
comes in the New Zealand Community’ (BIONIC) study
conducted in and around the city of Hamilton, in the North
Island of New Zealand [2]. This study sought to identify
all cases of TBI that occurred in this region across a 1-year
period. Potential participants were identified by searches of
hospital admission and discharge records, school and sports
club incident reports, and information obtained from gen-
eral practitioners in the community. A diagnostic adjudica-
tion group judged multiple sources of evidence to confirm
whether a TBI had been sustained, and if so, individuals
were invited to participate in the study. Only the mTBI cases
[defined as Glasgow Coma Scale (GCS) score between 13

Quality of Life Research
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and 15 and/or less than 24h of post-traumatic amnesia]
were extracted for this analysis. For individuals satisfying
the inclusion criteria and indicating a willingness to partici-
pate, clinical interviews were undertaken using trained and
appropriately qualified research assistants at the participant’s
residence, or at a mutually agreed location such as a private
room at a medical practice.
In total, 170 males and 123 females who had experi-
enced a mTBI within 12months of the commencement of
the BIONIC study and had completed the 12-month post-
injury assessment phase were extracted from the BIONIC
dataset for this analysis. This represents 33.86% of incident
mTBIs identified in phase one (i.e. 1 month post TBI) of
the BIONIC study, where 452 participants in the original
BIONIC cohort did not consent to follow-up measures,
while 125 participants did not provide details of post-con-
cussion symptoms at 12months. Mean participant ages at
time of injury for males (M = 39.47, SD = 1.333, Min = 16,
Max = 87 years) and females (M = 36.26, SD = 1.635,
Min = 16, Max = 80years) were statistically indistinguish-
able (t(291) = 1.533, p = .126). Over half of the partici-
pants (n = 165) disclosed that this was not their first mTBI.
In terms of mTBI severity, 36 (12.3%) were classified as
mild-low risk, 54 (18.4%) were mild-medium risk, and 203
(69.3%) were mild-high risk. As for education, most had
attended high school (n = 104), while eight participants had
not, and approximately 40% went on to further study in
either a polytechnic (n = 65) or university (n = 50).
Measures
Health‑related quality oflife
Health-related quality of life was measured at 12 months
post TBI using the SF-36v2 health status questionnaire
[27]. The SF-36 presents 36 self-report health-related items
containing three, five or six response categories, and asks
people for their views on their health in the last 4 weeks.
The SF-36 is commonly reported in TBI research [28] and
is generally accepted as an appropriate measure to use with
TBI patients, and has been shown to be a valid and reliable
instrument (for a review see [18]). The SF-36 contains eight
domains capturing physical, mental, and social function-
ing: physical functioning (PF), role limitations related to
physical functioning (RP), bodily pain (BP), general health
perception (GH), vitality (VT), social functioning (SF),
role limitations related to emotional problems (RE), and
mental health (MH). Each domain has a transformed scale
score ranging from 0 to 100. Additionally, the standardised
domain scores were used to calculate two summary scores:
the Physical Component (PF, RP, BP, GH, and VT) and the
mental component (SF, RE, and MH) summary scores [29].
For all SF-36 domains and summary scores, higher values
indicate higher HRQOL.
Noise andlight sensitivity
Measures of noise and light sensitivity were taken from the
RPQ: [7], specifically the fourth [compared with before the
accident, do you now (i.e. over the last 24h) suffer from
noise sensitivity, easily upset by loud noise] and fourteenth
[compared with before the accident, do you now (i.e. over
the last 24h) suffer from Light Sensitivity, easily upset by
bright light] items. Participants responded using a five-
point scale, and based their ratings on the previous 24h,
and with reference to their pre-injury state. The five-point
scale was 0 (not experienced at all), 1 (no more of a prob-
lem), 2 (a mild problem), 3 (a moderate problem) and 5 (a
severe problem). The use of single-item sensitivity items
has support in the literature (e.g. [16, 30]), and the isolated
use of RPQ sensitivity items has been previously reported
in the mTBI literature [3, 15]. For the purposes of this study,
those responding “not experienced at all” were classified as
non-sensitive, while responses to any of the remaining four
categories was classed as sensitive. The RPQ scale has been
used widely in concussion research, and is typically reported
to be a valid and reliable instrument for the collection of TBI
data, including in the current study [31].
Data analysis
All analyses were conducted in SPSS v.25, which was also
used to confirm that all test assumptions were satisfied prior
to analysis. Firstly, descriptive statistics were derived and
rates of noise and light sensitivity calculated. Secondly, a set
of independent samples t tests were performed to compare
SF-36 scores across those with and those without noise and
light sensitivity. A significant difference in means required
a p value to be less than the Bonferroni-corrected alpha of
.0025 (2-tailed). Thirdly, hierarchical multiple linear regres-
sions were undertaken to estimate the proportion of variance
in SF-36 domain and component scores that noise and light
sensitivity could account for. In these models, the dependent
variable was one of the eight SF-36 domain scores, or either
of the two component scores. In the first step, demographic
(gender, age at injury, and education) and mTBI-related
measures (mTBI severity and number of previous mTBIs)
known to affect HRQOL were entered as control variables.
In the second step, noise sensitivity and light sensitivity
scores were entered. A significant change in R2 (ΔR2) from
Step 1 to Step 2 was interpreted as evidence of an independ-
ent relationship between the dependent variable and noise
and light sensitivity. The standardised regression coefficient
(β) was used to quantify the relative contribution of the two
sensitivities. Note that participants using the ‘1’ category

Quality of Life Research
1 3
(no more of a problem) for either (or both) of the noise and
light sensitivity items in the RPQ were not include in the
regression analyses, as recommended by King etal. [7].
Results
Preliminary analysis
Noise and light sensitivity were reported by 124 (42.3%)
and 125 (41.9%) individuals, respectively (Table1). A total
of 32 individuals reported noise but not light sensitivity,
compared to 31 reports of light but not noise sensitivity.
Of those reporting sensitivities, mean scale ratings were
2.02 (SD = .945) for noise, and 1.99 (SD = 1.08) for light
sensitivity, and for the whole sample these means were .86
(SD = 1.18) and .84 (SD = 1.21), respectively. For those
reporting both light and noise sensitivity (n = 91), a moder-
ate correlation between noise and light sensitivity ratings
was noted (r = .453, p < .001). Table2 presents mean scores
for the SF-36 domains, with higher means noted for those in
the non-sensitive groups versus those reporting sensitivity.
Separate independent samples t tests between those report-
ing and those not reporting noise sensitivity were significant
across the ten SF-36 scores (all p < .001), and the same pat-
tern of significance was noted for light sensitivity. Notably,
statistical significance is retained even after the application
of a Bonferroni adjustment. The same pattern of statisti-
cal significance was also noted for those reporting dual
sensitivities.
Relationship betweensensory sensitivities
andSF‑36
Initial correlation analyses indicated shared variance
between the noise sensitivity score and the subscales and
summary scores of the SF-36 (all p < .001), ranging from
r = − .236 (physical functioning) to r = − .426 (social func-
tioning), with a mean of r = − .37 (SD = .058). For light
sensitivity, coefficients ranged from r = − .280 (physi-
cal functioning) to r = − .479 (bodily pain), with a mean
of r = − .40 (SD = .052). Hierarchical regression analyses
with controlling variables in the first step (gender, age at
injury, education, mTBI severity (classified as mild-low,
mild-medium, and mild-severe risk), and total number of
recurrent mTBIs) and the two sensory sensitivities in the
second step were undertaken to determine if sensory scores
could explain additional variability in the SF-36 scores (the
dependent variables). Results are displayed in Table3, with
the addition of the sensory sensitivity variables explaining
a statistically significant amount of variance in the SF-36
Table 1 Frequency of participants reporting light and noise sensitiv-
ity for each of the five categories making up a RPQ scale
Data are presented for the entire sample and separately for those
reporting dual sensitivity. Parentheses contain percentages
Entire sample (n = 293) Dual sensitivity
(n = 91)
Light Noise Light Noise
Not experienced
at all
169 (57.68) 168 (57.34) – –
No more of a
problem
54 (18.43) 43 (14.68) 36 (39.56) 27 (29.67)
A mild problem 32 (10.92) 46 (15.70) 27 (29.67) 32 (35.16)
A moderate
problem
21 (7.17) 26 (8.87) 12 (13.19) 23 (25.27)
A severe problem 17 (5.80) 10 (3.41) 16 (17.58) 9 (10.99)
Table 2 Mean SF-36 subscales
and summary scores at 1 year
post mTBI for the different
sensory sensitivity categories
Note that all pairwise comparisons between the non-sensitive group and the three sensitivity groups (noise,
light, and dual) were statistically significant (p < .05)
SF-36 scores (0–100) Dual Noise Light
Sensitivity
(n = 91)
Sensitive
(n = 126)
Non-sensitive
(n = 167)
Sensitive
(n = 123)
Non-sensitive
(n = 169)
Physical functioning 80.78 (24.49) 81.68 (24.15) 89.16 (19.84) 81.40 (24.67) 89.32 (19.34)
Role physical 49.72 (42.65) 53.28 (43.36) 77.40 (34.63) 53.51 (42.00) 77.08 (36.03)
Bodily pain 52.86 (26.84) 58.60 (27.27) 74.54 (25.33) 55.79 (27.61) 76.47 (23.58)
General health 57.01 (24.90) 61.16 (25.02) 75.96 (19.41) 60.32 (24.56) 76.48 (19.43)
Vitality 48.28 (23.13) 50.78 (23.64) 65.75 (20.28) 51.98 (23.44) 64.79 (21.08)
Social functioning 65.42 (31.53) 70.18 (30.89) 85.48 (21.84) 70.04 (30.51) 85.49 (22.24)
Role emotional 62.96 (43.40) 68.03 (41.86) 89.62 (24.24) 67.77 (41.04) 89.68 (25.26)
Mental health 68.58 (20.45) 70.62 (20.02) 79.98 (17.27) 70.78 (20.55) 79.81 (16.91)
SF-36 composite scores
Physical CS 43.15 (11.80) 44.37 (11.61) 49.58 (9.17) 43.83 (11.69) 49.94 (8.87)
Mental CS 41.02 (13.59) 42.91 (13.56) 50.80 (10.63) 43.21 (13.70) 50.54 (10.70)

Quality of Life Research
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even after accounting for the controlling variables. Visual
inspection of Table3 reveals a number of interesting trends.
First, standardised B values (β) are on average lower for
noise (Mβ = − .187, SD = .064) than light (Mβ = − .271,
SD = .073) sensitivity (t(9) = 2.806, p = .021). Second, the
maximum value of the β coefficients differs according to
sensory modalities, with the peak for noise sensitivity (role
emotional) differing from that observed with light sensitivity
(bodily pain). Of note, the weakest relationship documented
between noise sensitivity and the SF-36 domains (mental
health) coincides with the second highest relationship for
light sensitivity. Third, the proportion of variance explained
by the addition of noise and light sensitivity scores is gener-
ally high, ranging from 4 (physical functioning) to 26% (role
emotional). Across the ten SF-36 scores, the mean ΔR2 was
.161 (SD = .062).
Discussion
The current study focused on associations between both
noise and light sensitivity and HRQOL 12 months post
mTBI. As recommended by the creator of the RPQ [7], con-
sidering only item responses greater-or-equal to two, and
negating the zero and one categories, the current study indi-
cates that approximately one-in-five individuals are strug-
gling with either noise, light, or both, 12 months following
a mTBI. Compared to previous studies, the mean sensitivity
scores for the sample were nearly twice those reported in
a small-sample New Zealand study [31], but equivalent to
other figures reported in the literature [12]. Furthermore,
of those reporting sensitivities, about a third experienced
noise and light sensitivity concurrently, and so can be clas-
sified as having dual sensory impairment. Lew etal. [14]
reported that 32% of their TBI sample met the criterion for
dual sensory impairment, similar to the overall 31% noted
in the current sample. As such, a substantial proportion of
individuals with mTBI may be negatively impacted by sen-
sory impairment, which may corrupt neuropsychological
processes via sensory overload, and from a psychosocial
perspective, degrade quality of life.
The between reduced HRQOL and mTBI has been fre-
quently reported in the literature, mostly by reporting group
comparisons between controls and individuals with mTBI
(e.g. [32, 33]). Our mean SF-36 scores are consistent with
those reported in the TBI liassociationterature (e.g. [26, 28]),
and lower than New Zealand national norms [34]. Addition-
ally, we found statistically significant differences in SF-36
scores across those reporting sensory sensitivities and those
not (Table2). For the most extreme difference, decreases of
31.2% and 30.1% in role physical scores were noted for those
reporting noise and light sensitivities, respectively. The role
physical domain embodies difficulty in performing tasks,
and our findings indicate that sensory sensitivities may be
impeding both ability to engage in and perform tasks affect-
ing community participation, and as such may constitute a
barrier to returning to meaningful employment.
The negative association of sensory sensitivity on
HRQOL was further emphasised in the results of the hierar-
chical multiple linear regressions (Table3). Here, the addi-
tional variance explained by adding a linear combination of
noise and light sensitivity scores ranged from 4 (physical
functioning) to 26% (role emotional). For the physical health
domains, the greatest influence of the two sensitivities was
Table 3 Results of hierarchical regression analyses (n = 217)
The noise and light sensitivity values come from the second step in the model. The superscript digits (1 = age at mTBI, 2 = gender) presented in
the left-most column represent the control variables in Step 1 that retained significance in Step 2
***p < .001, **p < .01, *p < .05
a Age at mTBI p < .05. bGender p < .05
Model R2Noise sensitivity Light sensitivity
Step 1 Step 2 ∆R2BSE β B SE β
SF-36 physical health domains
Physical functioninga.170*** 0.252 .082*** − 3.315 2.346 − 0.144 − 4.299 2.003 − .205*
Role physicala.076** 0.314 .238*** − 17.93 4.272 − .368*** − 8.711 3.648 − 2.39*
Bodily paina,b .103** 0.376 .273*** − 8.309 2.887 − .240** − 11.197 2.465 − .379***
General health .057** 0.281 .224*** − 6.557 2.585 − .228** − 8.219 2.207 − .334***
Vitalitya,b .106** 0.303 .196*** − 6.502 2.614 − 0.22 − 7.766 2.232 − .307***
Social functioning 0.048 0.286 .238*** − 12.33 3.179 − 3.46** − 7.096 2.715 − .262**
Role emotional 0.049 0.398 .349*** − 18.55 3.135 − .415*** − 10.95 3.135 .286***
Mental health .069* 0.284 .215*** − 5.868 2.36 − 0.223 − 7.404 2.015 − .328***
Physical CSa.124*** 0.28 .156*** − 2.854 1.069 − .240* − 2.364 0.913 − .232**
Mental CS 0.068 0.332 .264*** − 5.265 1536 − .297** − 4.797 1.311 − .316***

Quality of Life Research
1 3
on the bodily pain domain, which accounts for perceptions
of pain and the extent to which pain affects work. Of rel-
evance, hyperacusis, which is characterised by ear pain aris-
ing from damage to the inner ear [35], has been associated
with sports-related concussion [5]. Likewise, increased sen-
sitivity to light (i.e. ‘photosensitivity’) has also been associ-
ated with pain [36], and light sensitivity has been associated
with sleep disturbance, vertigo, and fatigue, all of which are
common post-concussive symptoms. For the mental health
domains, the role emotional domain was most influenced
by the two sensitivities, indicating that noise and light are
potentially inducing maladaptive emotional responses in
individuals with mTBI, and interfering with goal-directed
behaviours. In the noise literature, these adverse psychologi-
cal responses are termed ‘noise annoyance’, and in the mTBI
context could potentially increase social isolation [23] and,
as our data suggest, lower HRQOL.
The literature typically reports equivalent rates of noise
and light sensitivity 12 months after sustaining a mTBI [e.g.
12, 13, 32]. However, noise sensitivity is typically singled
out as having the greater influence on clinical symptoms
[3, 15, 16]. The one exception comes from Wojcik [17],
who reported that light sensitivity was a superior prognos-
tic measure than noise sensitivity. Our analysis afforded an
examination of the independent effects of noise and light
sensitivity on HRQOL, and because the noise-sensitive
and light-sensitive variables explained unique variance in
SF-36, the impact of negative effect on these relationships
will be attenuated. As per Table3, all β-values associated
with the noise and light sensitivity scores were statistically
significant; however, with the exception of role physical,
the β-values were greater for light sensitivity, indicating
that reactivity to light was in general having a greater influ-
ence on HRQOL than reactivity to noise. In evolutionary
schemes, vision is our dominant sense, and our reliance on
vision to navigate and manipulate our host environments
suggests that impairments to this modality will severely
compromise health and well-being. Furthermore, unlike
the auditory modality whereby ear-protection (e.g. muffs
or plugs) or avoidance behaviours can be used to mitigate
increased sensitivity, there is less opportunity for mitigation
in the visual modality, though sunglasses are an option [23].
Heightened sensitivity to noise and light may result from
diffuse axonal injury to the central auditory pathway [37]
or localised or diffuse damage to those areas of the brain
involved with visual processing [38]. Despite the existence
of a credible aetiology, few studies have directly investigated
the impacts of post-TBI sensory impairments on long-term
health, and standardised clinical practices to these typically
overlooked symptoms are limited [6, 14]. The current study
enhances the knowledge base by emphasising the impact that
sensory-related post-concussive symptoms have on HRQOL,
and argues for the validation of noise and light sensitivity as
TBI symptoms in their own right. As such, greater attention to
these symptoms during rehabilitation may ultimately reduce
treatment times and lower health costs. Further, focused treat-
ment plans addressing sensory factors may in some cases help
in symptom reduction and ensure better health outcomes.
Systematic reviews on treatment of post-concussive symp-
toms [39] note that early education is significantly linked to
decreased post-concussive symptomology in mTBI patients,
and that even a single early education session can result in a
reduction of persistent symptoms [40]. A psychoeducational
intervention usually involves the provision of information
related to the condition and associated symptoms, normalisa-
tion of symptoms experienced, reassurance of positive expec-
tations of recovery, and the provision of information on strate-
gies to cope with the illness [41], all of which can be applied
to sensory symptoms.
Strengths andlimitations
The study’s key strength is the population-based approach
employed to identify TBI cases that captured many of those
individuals with brain injuries that may not have necessarily
attended hospital. Another strength is the use of clinicians to
formally assess participants and diagnose the severity of the
TBI, rather than relying on self-report. However, a limitation
of studies conducted at the population level is the lack of pre-
injury measures, which would have better clarified the impact
of TBI on participants’ HRQOL scores. A further limitation
is the inability to compare data from participants to those who
were lost to follow-up. While there were no demographic or
injury differences between those who completed the follow-
up assessments and those who did not [42], it cannot be con-
cluded that the two groups had equivalent sequelae and, for
example, those with more positive treatment outcomes may be
less inclined to take part. How to best manage the ‘1’ (no more
of a problem) category in the original RPQ scale as used in the
current study is problematic, particularly due to the ambigu-
ity in its phrasing and reference to pre-injury functioning. As
such the item can be dropped completely [7] or combined with
the ‘0’ (not experienced at all) category following rewording
[e.g. 3], but as we used the scales original phrasing we were
constrained to adopt the former method, albeit with the loss
of valuable data. Finally, as the study utilises a cross-sectional
design, the findings should not be interpreted as a causal rela-
tionship between sensitivities and HRQOL without the provi-
sion of further evidence.
Conclusion
To conclude, these findings suggest that individuals experi-
encing sensory impairments following a mild TBI may find
it more challenging to restore their pre-TBI quality of life.

Quality of Life Research
1 3
The prevalence of sensory issues in our sample indicates that
light and noise sensitivity are of high clinical relevance, and
as such the development of clinical protocols affording a uni-
versal standard of care across health professionals is a desir-
able goal. Further, while the complexities inherent in TBI
symptomology create scientific challenges when attempting
to elucidate the biological underpinnings of sequelae such as
sensory impairments, the associations between these symp-
toms and HRQOL clearly reinforce the argument to advance
aetiology so they can be tackled at the clinical level.
Compliance with ethical standards
Conflict of interest All the authors declare that they have no conflict
of interest.
Ethical approval Ethical approval for this study was obtained from the
Northern Y Health and Disability ethics committee of New Zealand
(NTY/09/09/095).
Informed consent Informed consent was obtained from all individual
participants included in the study.
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