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INTRODUCTION: Neuromuscular clinical manifestations during acute West Nile virus (WNV) infection are well documented; however, long-term neurologic outcomes still require investigation. METHODS: We conducted a long-term follow-up study in patients with history of WNV infection. Of the 117 patients who participated in neurologic and neurocognitive evaluations, 30 were referred for neuromuscular and electrodiagnostic evaluation based on abnormal findings. RESULTS: We found that 33% of these patients (10 of 30) showed abnormalities on nerve conduction and/or needle electromyography due to primary or secondary outcomes of WNV infection. Most common electrodiagnostic findings and causes of long-term disability were related to anterior horn cell poliomyelitis (WNV poliomyelitis). Electrical data on these patient populations were similar to those observed in chronic poliomyelitis. DISCUSSION: With more than 16,000 cases of WNV neuroinvasive disease reported across the USA since 1999, understanding clinical outcomes from infection will provide a resource for physicians managing long-term care of these patients. Muscle Nerve 57: 77-82, 2018.

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Neuropathy as extramuscular manifestation of dermatomyositis (DM) is controversial due to uncommon occurrence, heterogeneity of associated nerve pathology, and lack of unifying pathogenetic mechanism(s). We describe a patient with classic manifestations of DM and extramuscular manifestation of neuropathy. Nerve pathology showed deposits of terminal complement complex (C5b-9). Her examination showed mild proximal weakness, rash, and sensory impairment in fingertips, toes, and nose. EMG/NCS revealed irritable myopathy and mild sensory neuropathy. Muscle biopsy showed features suggestive of DM, including deposition of C5b-9. CK was elevated to 214 and ANA was positive at 1:160. Etiological work up for neuropathy, including diabetes, was negative. Sural nerve biopsy at light level revealed very mild large fiber sensory neuropathy. EM showed moderately severe involvement of small sensory fibers. Neuropathy may be an underrecognized manifestation of DM. Nerve pathology demonstrating complement-mediated damage could be a unifying mechanism of muscle and nerve injury.

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INTRODUCTION: Electrodiagnostic features of demyelination are essential for establishing the diagnosis in demyelinating subtypes of Guillain-Barré syndrome (GBS), but they may also occur in disorders that mimic GBS clinically. Information about their frequency in GBS mimics is sparse. METHODS: Evaluation of electrodiagnostic features from 38 patients with suspected GBS in whom the diagnosis was later refuted (GBS mimics). Their diagnostic accuracy was analyzed by comparison with nerve conduction studies (NCS) from 73 confirmed GBS patients. RESULTS: Disorders that mimicked GBS clinically at the time of hospital admission included other inflammatory, metabolic, toxic, or infectious neuropathies and spinal cord disorders. The sural sparing pattern was the most specific electrodiagnostic feature for demyelinating GBS. CONCLUSIONS: Common electrodiagnostic abnormalities in early demyelinating GBS do not usually exclude other rare differential diagnoses. An exception to this is the sural sparing pattern described here, which strongly supports the diagnosis of demyelinating GBS.

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PURPOSE: To implement high resolution diffusion tensor imaging (DTI) for visualization and quantification of peripheral nerves in human forearm. MATERIALS AND METHODS: This HIPAA-compliant study was approved by our Institutional Review Board and written informed consent was obtained from all the study participants. Images were acquired with T1 -and T2 -weighted turbo spin echo with/without fat saturation, short tau inversion recovery (STIR). In addition, high spatial resolution (1.0 × 1.0 × 3.0 mm(3) ) DTI sequence was optimized for clearly visualizing ulnar, superficial radial and median nerves in the forearm. Maps of the DTI derived indices, fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (λ// ) and radial diffusivity (λ⊥ ) were generated. RESULTS: For the first time, the three peripheral nerves, ulnar, superficial radial, and median, were visualized unequivocally on high resolution DTI-derived maps. DTI delineated the forearm nerves more clearly than other sequences. Significant differences in the DTI-derived measures, FA, MD, λ// and λ⊥ , were observed among the three nerves. A strong correlation between the nerve size derived from FA map and T2 -weighted images was observed. CONCLUSION: High spatial resolution DTI is superior in identifying and quantifying the median, ulnar, and superficial radial nerves in human forearm. Consistent visualization of small nerves and nerve branches is possible with high spatial resolution DTI. These normative data could potentially help in identifying pathology in diseased nerves. J. Magn. Reson. Imaging 2014;39:1374-1383. © 2013 Wiley Periodicals, Inc.

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PURPOSE: The authors performed a study using disposable disk electrodes, currently used to record motor nerve conduction study, for median antidromic sensory recording from the second digit with the aim of establishing efficiency by using one type of electrode throughout the entire nerve conduction study. This study aims to establish noninferiority with the use of disk electrodes rather than conventionally used nondisposable ring electrodes in the diagnosis of carpal tunnel syndrome. METHODS: For median sensory response, 4 parameters were studied: (1) onset latency, (2) peak latency, (3) amplitude, and (4) conduction velocity. Ten hands with active disease and 10 control hands without disease were studied via both ring electrodes and disk electrodes. The results were compared between the ring and disk electrodes. RESULTS: There was no statistically significant difference between the ring electrodes and the disk electrodes in recording the four parameters of the antidromic median sensory nerve conduction study using the second digit. CONCLUSIONS: Our study indicates that disposable disk electrodes could replace ring electrodes to perform median sensory antidromic nerve conduction studies for the diagnosis of carpal tunnel syndrome. However, further studies need to be carried out with larger sample sizes and for other indications.

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We report a case of familial amyotrophic lateral sclerosis (FALS) with clinical signs of cerebellar and posterior column involvement. The patient's work-up showed a known mutation (E100K) in the gene for Cu/Zn superoxide dismutase 1 (SOD1). Our case illustrates that extramotor symptoms, such as prominent cerebellar signs, can be seen in patients with FALS.

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