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Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis (SWN) are three clinically distinct tumor predisposition syndromes with a shared tendency to develop peripheral and central nervous system neoplasms. Disease expression and complications of NF1, NF2, and SWN are highly variable, necessitating a multidisciplinary approach to care in order to optimize outcomes. This review will discuss the imaging appearance of NF1, NF2, and SWN and highlight the important role that imaging plays in informing management decisions in people with tumors associated with these syndromes. Recent technological advances, including the role of both whole-body and localized imaging strategies, routine anatomic and advanced magnetic resonance (MR) imaging sequences such as diffusion-weighted imaging (DWI) with quantitative apparent diffusion coefficient (ADC) mapping, and metabolic imaging techniques (MR spectroscopy and positron emission testing) are discussed in the context of the diagnosis and management of people with NF1, NF2, and SWN based on the most up-to-date clinical imaging studies.

Objective: This study aimed to investigate the diagnostic accuracy of magnetic resonance (MR) imaging for categorizing sciatic peripheral nerve injury (PNI) as high-grade (Sunderland grades IV-V) or low-grade (Sunderland grades I-III) PNI., Methods: In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study, consecutive MR imaging of the pelvis and thighs, performed for the evaluation of traumatic sciatic neuropathy, was reviewed for sciatic nerve signal intensity, size, architectural distortion, bulbous enlargement, perineural fibrosis, discontinuity, and muscle denervation changes. Clinical data, electrodiagnostic testing, and surgical history were used to determine PNI grade (high, low). Descriptive and diagnostic performance statistics were applied., Results: Of 24 patients, there were 12 high-grade and 12 low-grade PNI. There was no significant difference in signal intensity or size between high-grade and low-grade PNI (1.3 ± 0.5 cm vs 0.9 ± 0.3 cm, P = 0.09). The sensitivity and specificity for the presence of individual features in predicting high-grade injury were 83% and 67% for architectural distortion, 58% and 75% for bulbous enlargement, 50% and 83% for perineural fibrosis, 25% and 100% for discontinuity, and 67% and 75% for skeletal muscle denervation changes, respectively. Overall, the sensitivity and specificity of MR imaging for categorizing sciatic PNI as high grade was 75% and 83%, respectively., Conclusions: The MR characterization of PNI severity remains challenging. Useful features indicative of high-grade PNI include bulbous enlargement, perineural fibrosis, muscle denervation changes, and nerve discontinuity.

Purpose To determine if 3-T magnetic resonance (MR) neurography-guided retroperitoneal genitofemoral nerve (GFN) blocks are safe and effective for the diagnosis of genitofemoral neuralgia. Materials and Methods Following institutional review board approval and informed consent, 26 subjects (16 men, 10 women; mean age, 42 years [range, 24-78 years]; mean body mass index, 28 kg/m 2 [range, 20-35 kg/m 2 ]) with intractable groin pain were included. By using a 3-T MR imaging system, intermediate-weighted turbo spin-echo pulse sequences, and MR-conditional needles, diagnostic MR neurography-guided GFN blocks were performed in the retroperitoneum. Outcome variables included technical success, procedure time, complications, and rates of positive and negative GFN blocks in association with therapeutic outcomes. For the assessment of a learning curve, Mann-Whitney test was used. P values ≤ .05 were considered to indicate a statistically significant difference. Results In 26 subjects, 30 retroperitoneal GFN blocks were performed. Twelve (40%) were performed with an anterior needle path, 12 (40%) with a lateral needle path, and six (20%) with a posterior needle path. GFN blocks were technically successful in 24 of 26 (92%) subjects, achieving appropriate scrotal anesthesia. No complications occurred. The time required for a GFN block was 40 minutes (range, 18-67 minutes). The rate of a successful GFN intervention after a positive GFN block was 88% (14 of 16). The rate of a successful intervention of an alternative target after a negative GFN block was 71% (five of seven). Conclusion Selective retroperitoneally directed MR neurography-guided GFN blocks are safe and effective with high technical success and positive effect on surgical decision making in patients with presumed genitofemoral neuralgia. © RSNA, 2017 Online supplemental material is available for this article.

Objective: To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis., Materials and Methods: Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied., Results: Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy., Conclusion: MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips.

Objective: To evaluate the impact of magnetic resonance neurography (MRN) on diagnostic thinking and therapeutic choices in patients with suspected peripheral neuropathy., Methods: IRB approval was obtained for this HIPAA-compliant study. Questionnaires were administered to six surgeons regarding the diagnosis and treatment in 85 patients suspected of having peripheral neuropathy, before (pretest) and after (posttest) MRN. Multiple outcome measures related to diagnostic confidence and surgical decision-making were assessed., Results: The final cohort included 81 patients (30 men and 51 women, age 47 ± 17 years). The following changes were observed from pretest to posttest questionnaires: 23% in nerve involvement (P < 0.05), 48% in degree of confidence of nerve involvement (P < 0.01), 27% in grade of injury (P < 0.05), 33% in differential diagnosis (P < 0.05), 63% in degree of confidence in need for surgery (P < 0.001), 41% in timing of surgery (P < 0.01), 30% in approach to surgery (P < 0.05), 58% in degree of confidence in approach to surgery (P < 0.001), 30% in estimated length of surgery (P < 0.05) and 27% in length of incision (P < 0.05). The dichotomous decision regarding surgical or nonsurgical treatment changed from pro to con in 17%., Conclusion: MRN results significantly influenced the diagnostic thinking and therapeutic recommendations of peripheral nerve surgeons., Key Points: • In patients with peripheral neuropathy, MRN significantly impacts diagnostic thinking. • In patients with peripheral neuropathy, MRN significantly impacts therapeutic choices. • 3-T MRN should be considered in presurgical planning of patients with peripheral neuropathy.

Objectives: To describe the MRI appearance of traumatic neuromas on non-contrast and contrast-enhanced MRI sequences., Methods: This IRB-approved, HIPAA-compliant study retrospectively reviewed 13 subjects with 20 neuromas. Two observers reviewed pre-operative MRIs for imaging features of neuroma (size, margin, capsule, signal intensity, heterogeneity, enhancement, neurogenic features and denervation) and the nerve segment distal to the traumatic neuroma. Descriptive statistics were reported. Pearson's correlation was used to examine the relationship between size of neuroma and parent nerve., Results: Of 20 neuromas, 13 were neuromas-in-continuity and seven were end-bulb neuromas. Neuromas had a mean size of 1.5 cm (range 0.6-4.8 cm), 100 % (20/20) had indistinct margins and 0 % (0/20) had a capsule. Eighty-eight percent (7/8) showed enhancement. All 100 % (20/20) had tail sign; 35 % (7/20) demonstrated discontinuity from the parent nerve. None showed a target sign. There was moderate positive correlation (r = 0.68, p = 0.001) with larger neuromas arising from larger parent nerves. MRI evaluation of the nerve segment distal to the neuroma showed increased size (mean size 0.5 cm ± 0.4 cm) compared to the parent nerve (mean size 0.3 cm ± 0.2 cm)., Conclusion: Since MRI features of neuromas include enhancement, intravenous contrast medium cannot be used to distinguish neuromas from peripheral nerve sheath tumours. The clinical history of trauma with the lack of a target sign are likely the most useful clues., Key Points: • MRI features of neuromas include enhancement and lack of a target sign. • Contrast material cannot be used to distinguish traumatic neuromas from PNSTs. • Traumatic neuromas can simulate peripheral nerve neoplasms on imaging.

OBJECTIVE. In this article, we will review the normal anatomy and imaging features of various neuromuscular abnormalities related to suprascapular neuropathy. CONCLUSION. Suprascapular neuropathy can be difficult to distinguish from rotator cuff pathology, plexopathy, and radiculopathy. Electrodiagnostic studies are considered the reference standard for diagnosis; however, high-resolution 3-T MR neurography (MRN) can play an important role. MRN enables direct visualization of the nerve and simultaneous assessment of the cervical spine, brachial plexus, and rotator cuff.

Objective: Sports-related peripheral nerve injuries are common among athletes and are often underrecognized because of symptom overlap with more usual sports-related bone, soft-tissue, and joint injuries., Conclusion: MRI plays an increasingly important role in the workup of peripheral nerve injuries and may reveal severe nerve abnormalities before they are diagnosed by electrodiagnostic testing or a clinical examination. Sport-specific peripheral nerve injuries and their MRI appearance will be discussed in this article.

Sclerotic (T2 dark) lesions of the spine are infrequent and, as a result, these are often missed or misdiagnosed. Plain films may not be always available during magnetic resonance imaging (MRI) readout. Knowledge of such lesions and their imaging appearances on MRI evaluation is essential for a reader. Additionally, a systematic approach is important to accurately diagnose these lesions. In this article we discuss the various causes of spinal sclerotic lesions, describe their MRI characteristics with relevant case examples, and outline a systematic approach to their evaluation., (Copyright © 2013 Wiley Periodicals, Inc.)

Neurofibromatosis type 1 (NF1) is a neurocutaneous syndrome characterized by the development of multiple peripheral nerve sheath tumors, the majority of which are benign neurofibromas. However, malignant peripheral nerve sheath tumors (MPNSTs) occur with a 10 % lifetime risk in patients with NF1, often developing within a neurofibroma. When clinical suspicion for an MPNST arises, imaging with FDG PET and MRI is performed to characterize a peripheral tumor for potential malignancy. In this report, we describe a patient with NF-1 who had two peripheral tumors with similar features by PET, both suspicious for MPNST, but differing features by MRI, one of which was subsequently determined to be an MPNST and the second to be a schwannoma.

The authors report a vascular malformation mimicking a plexiform peripheral nerve sheath tumor. Three Tesla magnetic resonance neurography with high-resolution anatomic and advanced functional diffusion tensor imaging was helpful in evaluating full extent of the lesion and characterizing its internal architecture.

Objective: To assess the diagnostic accuracy and observer performance of 3-Tesla magnetic resonance neurography (MRN) in the evaluation of meralgia paresthetica (MP)., Materials and Methods: Two independent readers were blinded to the clinical diagnosis and evaluated the MRN studies of the pelvis of 11 patients with MP and 28 control participants. In each study, the lateral femoral cutaneous nerves were assessed for signal alteration and/or neuroma formation, indicating lateral femoral cutaneous neuropathy, at various levels along their course. Intra- and inter-observer reliability was evaluated., Results: Both readers exhibited substantial intraobserver agreement in detecting signal alterations and neuroma formation of the lateral femoral cutaneous nerve (LFCN). The readers demonstrated moderate interobserver agreement in detecting signal alteration of the LFCN and poor interobserver agreement in diagnosing neuroma formation. Sensitivity, specificity, positive predictive value, and negative predictive value of LFCN neuropathy diagnosis were ≥ 71 % and ≥ 94 % for both readers respectively. The diagnostic test accuracy was ≥ 90 % for both readers., Conclusion: 3-Tesla MRN provides reliable and accurate diagnostic evaluation of meralgia paresthetica.

Objective: To assess the feasibility, technical success, and effectiveness of high-resolution magnetic resonance (MR)-guided posterior femoral cutaneous nerve (PFCN) blocks., Materials and Methods: A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 patients [6 (75%) female, 2 (25%) male; mean age, 47 years; range, 42-84 years] with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed with a clinical wide-bore 1.5-T MR imaging system. High-resolution MR imaging was utilized for visualization and targeting of the PFCN. Commercially available, MR-compatible 20-G needles were used for drug delivery. Variables assessed were technical success (defined as injectant surrounding the targeted PFCN on post-intervention MR images) effectiveness, (defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block), rate of complications, and length of procedure time., Results: MR-guided PFCN injections were technically successful in 12/12 cases (100%) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100%). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30-70) min., Conclusions: Our initial results demonstrate that this technique of selective MR-guided PFCN blocks is feasible and suggest high technical success and effectiveness. Larger studies are needed to confirm our initial results.

Sciatic nerve mass-like enlargement caused by peripheral nerve sheath tumors or neurocutaneous syndromes such as neurofibromatosis or schwannomatosis has been widely reported. Other causes of enlargement, such as from perineuroma, fibromatosis, neurolymphoma, amyloidosis, endometriosis, intraneural ganglion cyst, Charcot-Marie-Tooth disease, and chronic inflammatory demyelinating polyneuropathy are relatively rare. High-resolution magnetic resonance imaging (MRI) is an excellent non-invasive tool for the evaluation of such lesions. In this article, the authors discuss normal anatomy of the sciatic nerve and MRI findings of the above-mentioned lesions.

Objective: The sciatic nerve may normally exhibit mild T2 hyperintensity in MR neurography (MRN) images, rendering assessment of sciatic neuropathy difficult. The purpose of this case-control study was to evaluate whether a quantitative and qualitative analysis of the sciatic nerves and regional skeletal muscles increases the accuracy of MRN in detecting sciatic neuropathy., Materials and Methods: We retrospectively reviewed the MRN studies of the pelvis and thighs of 34 subjects (12 men and 22 women; mean [± SD] age, 50 ± 15 years), of which 17 had a final diagnosis of sciatic neuropathy according to electrodiagnostic or surgical confirmation, and 17 had no evidence of sciatic neuropathy and served as control subjects. On each side, the sciatic nerves were evaluated for signal intensity (SI), size, course, and fascicular shape, whereas the regional skeletal muscles were evaluated for edema, fatty replacement, and atrophy. In addition, the nerve-to-vessel SI ratio was registered for each side at the same time and 8 months later., Results: The sciatic nerves of the abnormal sides exhibited higher nerve-to-vessel SI ratios and higher incidences of T2 hyperintensity, enlargement, and abnormal fascicular shape compared to the nerves of the normal sides. The regional muscles of the abnormal sides demonstrated a higher grade of fatty infiltration and higher frequencies of edema and atrophy. A cutoff value of nerve-to-vessel SI ratio of 0.89 exhibited high sensitivity and specificity in predicting sciatic neuropathy. Calculation of the nerve-to-vessel SI ratio demonstrated excellent inter- and intraobserver reliability., Conclusion: Both qualitative and quantitative criteria should be used to suggest the MRN diagnosis of sciatic neuropathy.

The radial nerve is a continuation of the posterior cord of the brachial plexus and one of the major nerves that provide motor and sensory innervations to the forearm. MR imaging evaluation of the radial nerve pathology has been described in scattered case reports. Current high-field MR scanners enable high resolution and high contrast imaging of the peripheral nerves. This article reviews the 3 Tesla magnetic resonance neurography imaging of radial nerve anatomy and various pathologies affecting it with relevant case examples., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

For evaluation of thoracic outlet syndrome (TOS), 3 Tesla magnetic resonance neurography (MRN) is being increasingly used. The authors report the findings on 3 T MRN with surgical correlation in a rare case of neurologic TOS caused by anomalous costal pseudoarthrosis., (Copyright © 2011 Wiley Periodicals, Inc.)

Objective: MR neurography (MRN) has increasingly been used in clinical practice for the evaluation of peripheral nerve disease. This article reviews the historic perspective of MRN, the current imaging trends of this modality, and the future directions and applications that have shown potential for improved imaging and diagnostic capabilities., Conclusion: MRN has come a long way in the past 2 decades. Excellent depiction of 3D nerve anatomy and pathology is currently possible. Further technical developments in diffusion-based nerve and muscle imaging, whole-body MRN, and nerve-specific MR contrast agents will likely play a major role in advancing this novel field and understanding peripheral neuromuscular diseases in the years to come.

Rationale and Objectives: The purpose of this study was to illustrate the imaging findings on high-resolution 3T magnetic resonance neurography (MRN) in patients with suprascapular nerve (SSN) neuropathy., Materials and Methods: From 3T MRN examinations performed for brachial plexus evaluation in 51 patients over a 3-year period, 15 patients with final diagnosis of suprascapular neuropathy were recruited. The diagnosis was confirmed by electrodiagnostic studies (EDS), clinical, and/or surgical follow-up examinations. Studies performed for the evaluation of tumor, neurofibromatosis, or known diffuse polyneuropathy were excluded., Results: Two cases were excluded due to suboptimal imaging related to motion degradation and poor signal-to-noise ratio. MRN depicted asymmetric enlargement and/or abnormal T2 hyperintensity of C5 nerve root (10/13 cases), C6 nerve root (10/13 cases), both C5 and C6 nerve roots (7/13 cases), upper trunk (11/13 cases) and SSN (11/13 cases), and other brachial plexus segments involvement (4/13 cases). MR findings of denervation changes in the ipsilateral supraspinatus and infraspinatus muscles were detected in 12/13 cases. In all seven cases where contrast-enhanced images were available, MRN demonstrated enhancement of the denervated muscles but did not provide any additional information regarding the nerve abnormality. None of the MRN studies revealed a mass lesion along the course of the SSN., Conclusion: 3T MRN is a valuable diagnostic tool in clinically suspected cases of suprascapular neuropathy, because it can directly demonstrate the nerve abnormality, as well as secondary muscle denervation changes. The reader should be aware that brachial plexopathy may coexist in patients with clinical diagnosis of SSN neuropathy., (Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.)

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

Objective: To describe and illustrate the magnetic resonance imaging (MRI) anatomy of the anterior femoral cutaneous nerve (AFCN) and a new technique for cryoanalgesia of the AFCN for long-term analgesic treatment of recalcitrant AFCN-mediated neuropathic pain.Materials and Methods: Using a procedural high-resolution MRI technique, we describe the MRI anatomy of the AFCN. Three patients (mean age, 48 years; range, 41-67 years) with selective nerve block-verified recalcitrant AFCN-mediated anterior thigh pain were enrolled to undergo cryoanalgesia of the AFCN. Procedures were performed under MRI guidance using clinical wide-bore MR imaging systems and commercially available cryoablation system with MR-conditional probes. Outcome variables included technical success, clinical effectiveness including symptom relief measured on an 11-point visual analog scale, frequency of complications, and procedure time.Results: Procedural MRI allowed to successfully demonstrate the course of the AFCN, accurate cryoprobe placement, and monitoring of the ice ball, which resulted in technically successful iceball growth around the AFCN in all cases. All procedures were clinically effective, with median pain intensity decreasing from 8 (7-9) before the procedure to 1 (0-2) after the procedure. The cryoanalgesia effect persisted during a 12-month follow-up period in all three patients. No major complications occurred. The average total procedure time was 98 min (range, 85-125 min).Conclusion: We describe the MRI anatomy of the AFCN and a new technique for cryoanalgesia of the AFCN using MRI guidance, which permits identification of the AFCN, selective targeting, and iceball monitoring to achieve long-term AFCN-mediated neuropathic pain relief. [ABSTRACT FROM AUTHOR]

The article presents a case of an 18-year-old woman who was admitted due to pain in her right shoulder region, insidious in onset with no inciting event or glaring trauma. She underwent magnetic resonance (MR) imaging of the right upper extremity and open exploration of her right infraclavicular brachial plexus. She was eventually diagnosed with malignant glomus tumor of the brachial plexus and was treated with molecularly targeted therapy.