Fig 18 - uploaded by Jenny T. Bencardino
Content may be subject to copyright.
Pseudotumor resulting in superior and inferior gluteal nerve entrapment in a 75-year-old woman status post right THA, with right leg weakness and palpable mass. Axial PD image (A) shows a complex mass centered on the right hip, consistent with pseudotumor (arrow). Note fatty atrophy of the gluteus maximus (GMa), gluteus medius (GMe), gluteus minimus (GMi), and tensor fascia lata (TF) muscles and edema like signal (asterisk) on coronal T2 FS image (B) consistent with compression of the superior and inferior gluteal nerves.
Source publication
Recent advances in magnetic resonance (MR) imaging have revolutionized peripheral nerve imaging and made high-resolution acquisitions a clinical reality. High-resolution dedicated MR neurography techniques can show pathologic changes within the peripheral nerves as well as elucidate the underlying disorder or cause. Neurogenic pain arising from the...
Citations
... The evaluation of 3D NerveVIEW images before and after contrast administration was conducted using multiplanar reformation (MPR) and MIP (slice thickness = 3mm-20 mm) in a randomized order, respectively. Based on previous studies in obstetrics and gynecology, urology, and orthopedic (hip-related) surgeries that involved pelvic nerve injuries (Bohrer et al., 2009;Burge et al., 2014;Delaney et al., 2014;Yamashita et al., 2017), we identified the pelvic splanchnic nerves, pelvic plexus, superior gluteal nerves, and pudendal nerves as our target nerves. The quality of the bilateral nerve images was assessed using a 3-point grading scale, based on the presence of perineural artifacts, vascular interference, and the condition of the nerve trunk (Zhang et al., 2020), The grading scale was as follows: 2 = excellent, indicating good visualization without any vascular or artifactual interference; 1 = good, indicating moderate visualization with some vascular and artifactual interference; and 0 = poor, indicating poor visualization with severe vascular, artifactual, and noise issues. ...
Objective
To evaluate the effectiveness of 3D NerveVIEW sequence with gadolinium contrast on the visualization of pelvic nerves and their branches compared to that without contrast.
Methods
Participants were scanned twice using 3D NerveVIEW sequence with and without gadolinium contrast to acquire pelvic nerve images. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and contrast ratio of the nerves were calculated and compared to determine the quality of images. To subjectively assess, using a 3-point scale, branch nerves critical to therapeutic decision-making, including the pelvic splanchnic nerve and pelvic plexus, the superior gluteal nerve, and the pudendal nerve.
Results
In the 32 eligible participants after using contrast, the CNRs of the images of nerve-to-bone and nerve-to-vessel significantly increased (p < 0.05). The CR of the images with contrast of all nerve-to-surrounding tissues (i.e., bone, muscle, blood vessels, and fat) were also found significantly higher (p < 0.05). The assessment of observers also shows higher scores for images with contrast compared to images without contrast.
Conclusion
The 3D NerveVIEW sequence combined with gadolinium contrast improved vascular suppression, increased the contrast between pelvic nerves and surrounding tissue, and enhanced the visualization of nerves and their branches. This study may be helpful for the technically challenging preoperative planning of pelvic diseases surgery.
... Patients can develop gluteal contracture following multiple intramuscular injections especially in children, which can cause nerve entrapment in chronic stages (Chen et al. 2006). Changes in the alignment of the pelvis, femur, and spine and associated gluteal tendinopathy can affect normal excursion of sciatic nerve and trigger deep gluteal syndrome (Delaney et al. 2014). ...
Deep gluteal syndrome is a type of entrapment neuropathy of the deep gluteal space where patients present with chronic buttock pain and/numbness with or without sciatica. Piriformis syndrome is one of the etiologies of deep gluteal syndrome wherein there is suspected compression of static or dynamic sciatic nerve due to the piriformis muscle and its variations. Good clinical history and examination can help in raising the clinical suspicion for deep gluteal syndrome. Imaging not only aids in the diagnosis but also has a large role in the treatment of this condition. MR neurography is an indispensable aid for the diagnosis of neuromuscular alterations associated with this syndrome. During evaluation of the deep gluteal syndrome, discogenic etiology for sciatica needs to be excluded as well. Conservative management includes medications for pain relief and muscle relaxation and physiotherapy. Image-guided interventions like intramuscular Botox injection and perineural sciatic injection can provide longer term relief. Patients with a history of failed conservative management and image-guided interventions can be considered for surgical intervention. Timely diagnosis of deep gluteal syndrome can help guide patient management and avoid unnecessary procedures.
... Mixed nerve arises from the anterior division of L1 nerve root, with some contribution of T12 and runs anteriorly and inferiorly along the lateral border of the psoas major and quadrates lumborum muscles. It pierces the transversus abdominus muscle and runs within the lateral abdominal wall, above the iliac crest, before dividing into its lateral and anterior cutaneous branches [13,[19][20][21]. ...
... The lateral cutaneous branch arises above the iliac crest, piercing the internal, and external obliques to innervate the superior posterolateral gluteal skin. The anterior cutaneous branch continues between the transversus and internal obliques until it pierces the anterior abdominal wall muscles through and innervates the external oblique, approximately 2.5 above the superficial inguinal ring, to provide skin innervation above the mons pubis and lower part of the rectus abdominis [19][20][21]. ...
... Also a mixed nerve with a preponderance of sensory branches originating from the anterior divisions L2 with some contribution from the L1 nerve branch [21]. This nerve emerges directly inferior to the iliohypogastric and ilioinguinal nerves. ...
Introduction
Chronic pain is a frequent and notable complication after inguinal hernia repair, it has been extensively studied, but its management and diagnosis are still difficult. The cause of chronic pain following inguinal hernia surgery is usually multifactorial. This case series highlights the utility of MRI neurography (MRN) in evaluating the damage to inguinal nerves after a hernia repair, with surgical confirmation of the preoperative imaging findings.
Materials and Methods
A retrospective review was performed on patients who underwent inguinal mesh removal and triple denervation of the groin. Inclusion criteria included MRI neurography. All patients underwent surgical exploration of the inguinal canal for partial or complete mesh removal and triple denervation of the groin by the same senior surgeon.
Results
A total of nine patients who underwent triple denervation were included in this case series. MRN was then performed on 100% of patients. The postoperative mean VAS score adjusted for all patients was 1.6 (SD p), resulting in a 7.5 score difference compared to the preoperative VAS score (p). Since chronic groin pain can be a severely debilitating condition, diagnosis, and treatment become imperative.
Conclusion
MRN can detect direct and indirect signs of neuropathy even in the absence of a detectable compressive cause aids in management and diagnosis by finding the precise site of injury, and grading nerve injury to aid pre-operative assessment for the nerve surgeon. Thus, it is a valuable diagnostic tool to help with the diagnosis of nerve injuries in the setting of post-inguinal hernia groin pain.
... Accurate evaluation of the lumbosacral plexus roots is crucial for diagnosis and analysis of nerve damage, previously described in studies on nerve-sparing surgery plan for vertebral resection of Bertolotti syndrome [1], congenital spinal deformities [2], neural tumors in the lumbar spine [3], and lumbosacral plexus dosimetry for radiotherapy for pelvic cancers [4]. However, estimating the segmental changes in the lumbosacral plexus from spinal MR images remaining challenging [5,6]. ...
Purpose
It remains unclear whether concomitant changes in the thoracolumbar (TL) vertebrae and lumbar plexus roots seen in experimental embryology are present in humans with different vertebral formulas, particularly in humans with 18 TL vertebrae. We thus investigated the human lumbar plexus root changes occurring in spines with an additional TL vertebra (18TL).
Methods
The lumbosacral plexus was macroscopically dissected in TL anomaly cases found in 161 computed tomography examinations. TL anomalies were distinguished as simple abnormalities in total TL count and abnormal TL trade-offs, i.e., exchanges between the last thoracic and first lumbar vertebrae, and were analyzed separately.
Results
One additional TL vertebra (7C_18TL_5S) was observed in 4/159 cases (2.5%), excluding cases with cervical and sacral abnormalities. Different from the unclear shifts of nerve roots in cases with 16TL and 17TL trade-offs, the 18TL trade-off tended to involve a caudal shift at the cranial limit, without event change at the caudal limit. In addition, only one nerve segment shift was reconfirmed with a change in two vertebral segments from 16 to 18 TL vertebrae.
Conclusions
We revealed that concomitant changes in the lumbar plexus roots and vertebrae in humans with 18TL vertebrae may become more pronounced than those in humans with 16 or 17TL vertebrae, by approaching the typical mammalian TL formula (19TL). This study showed that the TL formula can be used to estimate changes in the lumbar plexus roots, which may assist in the planning of nerve-sparing spinal and pelvic surgery.
... As proposed by Feller in 1992, magnetic resonance neurography (MRN), generally using T2-weighted imaging, is considered a reliable reference standard for the diagnosis of lumbosacral radiculopathy [4]. Pathological changes within nerves, including those resulting from nerve compression, such as neuroedema, are most visible and can be best characterized under T2-weighting [5]. ...
... However, 3D FSE T2 imaging still has some drawbacks for MRN, including hyperintense vascular structure artifacts and long acquisition times [12,13]. Vascular structures alongside nerves, especially slowflowing venous structures, produce hyperintense signals that may be confused with nerve structures or perineural edema [5,12]. In the era of patient-centeredness, it is also important to consider both patient comfort and diagnostic performance when optimizing MRI protocols. ...
... 3D imaging has significantly increased the clinical applications of morphological MR neurography. The T2-weighted SPACE sequence has been optimized for the detection of neurological diseases [5]. Wang et al. used this sequence to obtain good brachial plexus and LSP images [24]. ...
Purpose
This study compares the performance of a 4-min multi-echo in steady-state acquisition (MENSA) with a 6-min fast spin echo with variable flip angle (CUBE) protocol for the assessment of lumbosacral plexus nerve root lesions.
Methods
Seventy-two subjects underwent MENSA and CUBE sequences on a 3.0-T MRI scanner. Two musculoskeletal radiologists independently assessed the images for quality and diagnostic capability. A qualitative assessment scoring system for image quality and quantitative nerve signal-to-noise ratio (SNR) and iliac vein and muscle contrast-to-noise ratios (CNR) was applied. Using surgical reports as the reference, sensitivity, specificity, accuracy, and area under the receiver operating characteristic curves (AUC) were evaluated. Intraclass correlation coefficients (ICC) and weighted kappa were used to calculate reliability.
Results
MENSA image quality rating (3.679 ± 0.47) was higher than for CUBE images (3.038 ± 0.68), and MENSA showed higher mean nerve root SNR (36.935 ± 8.33 vs. 27.777 ± 7.41), iliac vein CNR (24.678 ± 6.63 vs. 5.210 ± 3.93), and muscle CNR (19.414 ± 6.07 vs. 13.531 ± 0.65) than CUBE (P < 0.05). Weighted kappa and ICC values indicated good reliability. Sensitivity, specificity, and accuracy of diagnosis based on MENSA images were 96.23%, 89.47%, and 94.44%, respectively, and AUC was 0.929, compared with 92.45%, 84.21%, 90.28%, and 0.883 for CUBE images. The two correlated ROC curves were not significantly different. Weighted kappa values for intraobserver (0.758) and interobserver (0.768–0.818) reliability were substantial to perfect.
Conclusion
A time-efficient 4-min MENSA protocol exhibits superior image quality and high vascular contrast with the potential to produce high-resolution lumbosacral nerve root images.
... For example, early on intramuscular edema may develop followed by eventual atrophic fatty degeneration in the chronic phase [52]. Spinal nerves at levels L5 and S1 are commonly affected by recurrent rectal cancer, and thus, these changes may be seen in the obturator internus and gluteus muscles (Table 3) [53]. It is difficult to assess edema in the muscle in the acute phase with CT, Fat density in the right sacral foramen of the S1 (a: arrow) and S2 (a: arrowhead) is replaced with soft tissue density. ...
... An omental pedicle flap was used to fill the pelvic void. Postoperative CT shows no residual tumor in the pelvis and the omental pedicle flap filling the dead space in the pelvis (c: asterisk) Table 3 Muscle and innervating nerve roots [53] The asterisks mean innervation between muscles and nerve roots Muscle L5 S1 S2 S3 S4 ...
For rectal cancer, MRI plays an important role in assessing extramural tumor spread and informs surgical planning. The contemporary standardized management of rectal cancer with total mesorectal excision guided by imaging-based risk stratification has dramatically improved patient outcomes. Colonoscopy and CT are utilized in surveillance after surgery to detect intraluminal and extramural recurrence, respectively; however, local recurrence of rectal cancer remains a challenge because postoperative changes such as fat necrosis and fibrosis can resemble tumor recurrence; additionally, mucinous adenocarcinoma recurrence may mimic fluid collection or abscess on CT. MRI and ¹⁸F-FDG PET are problem-resolving modalities for equivocal imaging findings on CT. Treatment options for recurrent rectal cancer include pelvic exenteration to achieve radical (R0 resection) resection and intraoperative radiation therapy. After pathologic diagnosis of recurrence, imaging plays an essential role for evaluating the feasibility and approach of salvage surgery. Patterns of recurrence can be divided into axial/central, anterior, lateral, and posterior. Some lateral and posterior recurrence patterns especially in patients with neurogenic pain are associated with perineural invasion. Cross-sectional imaging, especially MRI and ¹⁸F-FDG PET, permit direct visualization of perineural spread, and contribute to determining the extent of resection. Multidisciplinary discussion is essential for treatment planning of locally recurrent rectal cancer. This review article illustrates surveillance strategy after initial surgery, imaging patterns of rectal cancer recurrence based on anatomic classification, highlights imaging findings of perineural spread on each modality, and discusses how resectability and contemporary surgical approaches are determined based on imaging findings.
Graphical abstract
... Mixed nerve, that arises from the anterior division of L1 nerve root, with some contribution of T12. and runs anteriorly and inferiorly along the lateral border of the psoas major and quadrates lumborum muscles. It pierces the transversus abdominus muscle and runs within the lateral abdominal wall, above the iliac crest, before dividing into its lateral and anterior cutaneous branches [13,19,20,21]. ...
... The lateral cutaneous branch arises above the iliac crest, piercing the internal and external obliques to innervate the superior posterolateral gluteal skin. The anterior cutaneous branch continues between the transversus and internal obliques until it pierces the anterior abdominal wall muscles through and innervates the external oblique, approximately 2.5 above the super cial inguinal ring, to provide skin innervation above the mons pubis and lower part of the rectus abdominis [19,20,21]. Genitofemoral Also a mixed nerve with a preponderance of sensory branches originating from the anterior divisions L2 with some contribution from the L1 nerve branch [21]. ...
... The anterior cutaneous branch continues between the transversus and internal obliques until it pierces the anterior abdominal wall muscles through and innervates the external oblique, approximately 2.5 above the super cial inguinal ring, to provide skin innervation above the mons pubis and lower part of the rectus abdominis [19,20,21]. Genitofemoral Also a mixed nerve with a preponderance of sensory branches originating from the anterior divisions L2 with some contribution from the L1 nerve branch [21]. This nerve emerges directly inferior to the iliohypogastric and ilioinguinal nerves. ...
Chronic pain is a frequent and notable complication after inguinal hernia repair, it has been extensively studied but its management and diagnosis are still difficult. The cause of chronic pain following inguinal hernia surgery is usually multifactorial. This case series highlights the utility of MRI neurography (MRN) in evaluating the damage to inguinal nerves after a hernia repair, with surgical confirmation of the preoperative imaging findings.
A retrospective review was performed on patients who underwent inguinal mesh removal and triple denervation of the groin. Inclusion criteria included MRI Neurography. All patients underwent surgical exploration of the inguinal canal for partial or complete mesh removal and triple denervation of the groin by the same senior surgeon.
A total of nine patients who underwent triple denervation were included in this case series. MRN was then performed on 100% of patients. The postoperative mean VAS score adjusted for all patients was 1.6 (SD p), resulting in a 7.5 score difference compared to the preoperative VAS score (p). Since chronic groin pain can be a severely debilitating condition, diagnosis and treatment become imperative.
MRN can detect direct and indirect signs of neuropathy even in the absence of a detectable compressive cause aids in management and diagnosis by finding the precise site of injury, and grading nerve injury to aid pre-operative assessment for the nerve surgeon. Thus, it is a valuable diagnostic tool to help with the diagnosis of nerve injuries in the setting of post-inguinal hernia groin pain.
... PSIF, so-called reversed fast imaging with steady-state precession (FISP), is a GRE sequence in which the dephasing of transverse magnetization drops the signal in flowing blood(34). The additional diffusion-gradient with a low b-value also suppresses the vascular flow signal by flow-related dephasing of the transverse magnetization(8,19). ...
Purpose MR neurography (MRN) is an imaging technique optimized to visualize the peripheral
nerves. This review
aimed to discover an optimized protocol for MRN of the lumbosacral plexus (LSP)
and identify evidence for the clinical benefit of lumbosacral plexopathies.
Materials and Methods We performed a systematic search of the two medical databases until September
2021. ‘Magnetic resonance imaging’, ‘lumbosacral plexus’,
‘neurologic disease’, or equivalent
terms were used to search the literature. We extracted information
on indications, MRN protocols for
LSP, and clinical efficacy from 55 studies among those searched.
Results MRN of the LSP is useful for displaying the distribution of peripheral nerve disease, guiding
perineural injections, and assessing extraspinal causes of sciatica. Three-dimensional short-tau inversion
recovery turbo spin-echo combined with vascular suppression is the mainstay of MRN.
Conclusion Future work on the MRN of LSP should be directed to technical maturation and clinical
validation
of efficacy.
... Of note, sacrococcygeal teratoma has a predilection to involve the pudendal nerve. 25 MRI can help delineate a compressive mass, perineural scarring, or nerve signal abnormality along the nerve course at the site of entrapment. Imaging of the contralateral nerve on the axial plane can help diagnose the pathologic nerve. ...
Clinical symptoms of pelvic entrapment neuropathies are widely variable and frequently nonspecific, thus rendering it difficult to localize and diagnose. Magnetic resonance imaging (MRI), and in particular MR neurography, has become increasingly important in the work-up of entrapment neuropathies involving the pelvic and hip nerves of the lumbosacral plexus. The major sensory and motor peripheral nerves of the pelvis and hip include the sciatic nerve, superior and inferior gluteal nerves, femoral nerve, lateral femoral cutaneous nerve, obturator nerve, and pudendal nerve. Familiarity with the anatomy and imaging appearance of normal and pathologic nerves in combination with clinical presentation is crucial in the diagnosis of entrapment neuropathies.
... Although several studies dealing with PNS imaging have been performed using MRT or MRN, [13][14][15][16] those methods are not yet well-established in clinical practice. MR tractography of the LSP is challenging due to the difficulty of acquiring high quality data and accurately estimating the PNS tracts. ...
MR tractography of the lumbosacral plexus (LSP) is challenging due to the difficulty of acquiring high quality data and accurately estimating the neuronal tracts. We proposed an algorithm for an accurate visualization and assessment of the major LSP bundles using the segmentation of the cauda equina as seed points for the initial starting area for the fiber tracking algorithm.
Twenty-six healthy volunteers underwent MRI examinations on a 3T MR scanner using the phased array coils with optimized measurement protocols for diffusion-weighted images and coronal T2 weighted 3D short-term inversion recovery sampling perfection with application optimized contrast using varying flip angle evaluation sequences used for LSP fiber reconstruction and MR neurography (MRN).
The fiber bundles reconstruction was optimized in terms of eliminating the muscle fibers contamination using the segmentation of cauda equina, the effects of the normalized quantitative anisotropy (NQA) and angular threshold on reconstruction of the LSP. In this study, the NQA parameter has been used for fiber tracking instead of fractional anisotropy (FA) and the regions of interest positioning was precisely adjusted bilaterally and symmetrically in each individual subject.
The diffusion data were processed in individual L3-S2 nerve fibers using the generalized Q-sampling imaging algorithm. Data (mean FA, mean diffusivity, axial diffusivity and radial diffusivity, and normalized quantitative anisotropy) were statistically analyzed using the linear mixed-effects model. The MR neurography was performed in MedINRIA and post-processed using the maximum intensity projection method to demonstrate LSP tracts in multiple planes.
FA values significantly decreased towards the sacral region ( P < .001); by contrast, mean diffusivity, axial diffusivity, radial diffusivity and NQA values significantly increased towards the sacral region ( P < .001).
Fiber tractography of the LSP was feasible in all examined subjects and closely corresponded with the nerves visible in the maximum intensity projection images of MR neurography. Usage of NQA instead of FA in the proposed algorithm enabled better separation of muscle and nerve fibers.
The presented algorithm yields a high quality reconstruction of the LSP bundles that may be helpful both in research and clinical practice.
