Rubin, Devon I.

Purpose: Complex repetitive discharges (CRDs) are incompletely understood needle electromyography (EMG) waveforms seen in both myopathic and neurogenic disorders including radiculopathies. This study aimed to clarify the significance of CRDs in patients with radiculopathies. Methods: This case–control study randomly identified 100 patients with needle EMG evidence of radiculopathy demonstrating at least one CRD in the electrodiagnostically involved myotome between January 2017 and January 2022. These patients were compared with 100 randomly selected patients with EMG evidence of radiculopathy without CRDs controlled for sex, age at EMG testing, and affected nerve root segment. Patient clinical symptoms, neurologic examination, EMG features, and imaging were analyzed. A paired sample t-test for categorial data and χ2 test for nonparametric data were used for statistical analysis with significance defined as P < 0.05. Results: Patients with radiculopathies with CRDs had longer disease duration averaging 59 months (range 1–480) compared with patients with radiculopathies without CRDs averaging 26 months (range 1–192, P < 0.01). Clinical symptoms of paresthesias and weakness were both significantly more common in patients with radiculopathies with CRDs than those without CRDs (P < 0.01 and 0.01, respectively). Needle EMG demonstrated a greater average number of muscles with neurogenic motor unit potentials per radiculopathy in patients with radiculopathies with CRDs compared with those without CRDs. Imaging studies of patients with radiculopathies with CRDs were more likely to reveal evidence of nerve root compression (P < 0.01). Conclusions: The presence of CRDs in patients with radiculopathies is consistent with clinically more symptomatic radiculopathies and a longer duration of nerve root compromise.

AbstractIntroduction/AimsComplex repetitive discharges (CRDs) are spontaneous electromyography (EMG) waveforms often associated with chronic neurogenic or myopathic diseases, but incidentally identified CRDs have also been described. In this study we describe the distribution and possible significance of incidentally seen CRDs in otherwise normal electrodiagnostic studies.MethodsA retrospective chart review was performed of all patients with CRDs incidentally documented on otherwise normal electrodiagnostic studies at Mayo Clinic from January 2013 through December 2020. Each patient's clinical symptoms, referral reason, electrodiagnostic report, and imaging studies were analyzed using descriptive statistics.ResultsNinety‐four patients (86 females; mean age, 62 years; range, 20 to 86 years) and 107 CRDs were studied. The most common neuromuscular reasons for electrodiagnostic referrals included radiculopathy, peripheral neuropathy, and myopathy. Mean symptom duration was 43 months (range, 1 to 312 months). Eighty‐five patients had a CRD identified in one muscle (range, in all patients, one to five muscles). CRDs were identified most frequently in tensor fasciae latae (n = 21), biceps brachii (n = 16), and gluteus maximus (n = 9). Of the 58 patients in whom imaging was available, 46 (79%) had abnormalities that corresponded to the myotome in which the CRDs were visualized, most commonly L5 (n = 19) and C6 (n = 12). Of these 46 patients, 28 (61%) were referred for radicular or limb pain.DiscussionCRDs can be incidentally noted on otherwise normal electrodiagnostic studies, most commonly in L5 and C6 myotomes. The mechanism of CRDs in the absence of electrodiagnostic features of axon loss or remodeling is unknown.

AbstractIntroduction/AimsAmyotrophic lateral sclerosis (ALS) is a progressive, fatal, neurodegenerative disorder of motor neurons in which the cause is mostly unknown. Early identification of genetic ALS cases, of which C9ORF72 (C9ALS) is the most frequent, can have important implications for evaluation, prognosis, and therapeutics. Here, we aimed to characterize the clinical and electrophysiological hallmarks of C9ALS and investigate differences from C9ORF72 negative ALS (non‐C9ALS).MethodsWe retrospectively reviewed clinical and electrodiagnostic (EDX) data for all genetically confirmed C9ALS cases seen between 1/1/2012 and 10/1/2020 who met Gold Coast criteria and compared them 1:1 with non‐C9ALS patients within the same time frame.ResultsA total of 99 C9ALS and 99 non‐C9ALS cases were identified. Compared to non‐C9ALS, C9ALS demonstrated higher prevalence in women, lesser racial variability, stronger family history of ALS, and higher frequency of upper motor neuron signs. EDX testing of C9ALS showed higher median sensory nerve and lower fibular compound muscle action potential amplitudes.DiscussionAlthough the differences between C9ALS and non‐C9ALS reached statistical significance in certain nerve conduction parameters, they were not sufficient to discriminate between groups on a case‐by‐case basis. Genetic testing is required to identify C9ALS patients.

AbstractIntroduction/AimsGraduate medical education programs must ensure residents and fellows acquire skills needed for independent practice. Workplace‐based observational assessments are informative but can be time‐ and resource‐intensive. In this study we sought to gather “relations‐to‐other‐variables” validity evidence for scores generated by the Electromyography Direct Observation Tool (EMG‐DOT) to inform its use as a measure of electrodiagnostic skill acquisition.MethodsScores on multiple assessments were compiled by trainees during Clinical Neurophysiology and Electromyography rotations at a large US academic medical center. Relationships between workplace‐based EMG‐DOT scores (n = 298) and scores on a prerequisite simulated patient exercise, patient experience surveys (n = 199), end‐of‐rotation evaluations (n = 301), and an American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) self‐assessment examination were assessed using Pearson correlations.ResultsAmong 23 trainees, EMG‐DOT scores assigned by physician raters correlated positively with end‐of‐rotation evaluations (r = 0.63, P = .001), but EMG‐DOT scores assigned by technician raters did not (r = 0.10, P = .663). When physician and technician ratings were combined, higher EMG‐DOT scores correlated with better patient experience survey scores (r = 0.42, P = .047), but not with simulated patient or AANEM self‐assessment examination scores.DiscussionEnd‐of‐rotation evaluations can provide valid assessments of trainee performance when completed by individuals with ample opportunities to directly observe trainees. Inclusion of observational assessments by technicians and patients provides a more comprehensive view of trainee performance. Workplace‐ and classroom‐based assessments provide complementary information about trainee performance, reflecting underlying differences in types of skills measured.

IntroductionGuillain-Barré syndrome precipitated by hepatitis E virus infection is rare, yet its incidence is increasing.Clinical FindingsA 57-year-old man was transferred from another facility with fatigue, orange urine, and progressive weakness over 4 to 6 weeks. Initial laboratory results included total bilirubin, 9.0 mg/dL; direct bilirubin, 6.4 mg/dL; aspartate aminotransferase, 1551 U/L; alanine aminotransferase, 3872 U/L; and alkaline phosphatase, 430 U/L. Immunoglobulin M and quantitative polymerase chain reaction test results were positive for hepatitis E virus. Contrast-enhanced magnetic resonance imaging of the brain and spine showed no gross abnormalities. Analysis of cerebrospinal fluid obtained by lumbar puncture revealed the following (reference values in parentheses): total white blood cell count, 15/μL (0–5/μL), with 33% neutrophils and 54% lymphocytes; protein, 0.045 g/dL (0.015–0.045 g/dL); and glucose, 95 mg/dL (within reference range). Neurological examination revealed weakness in both upper extremities, with proximal strength greater than distal strength. The patient could not elevate either lower extremity off the bed and had areflexia and reduced sensation throughout all extremities.DiagnosisGuillain-Barré syndrome secondary to acute hepatitis E virus infection was diagnosed on the basis of clinical characteristics, serum and cerebrospinal fluid analyses, and nerve conduction studies.ConclusionsNurses and clinicians should obtain a thorough history and consider hepatitis E virus infection as a precipitating factor in patients with sensory and motor disturbances consistent with Guillain-Barré syndrome. The case gives insight into the diagnostic process for Guillain-Barré syndrome and highlights the vital role of bedside nurses in evaluating and treating these patients.

Purpose: To survey US Clinical Neurophysiology (CNP) fellowship program directors on the nature of CNP and related training programs, current recruitment cycle, and views for a standardized process. Methods: A 23-question electronic survey was sent to all 93 US Accreditation Council for Graduate Medical Education-accredited CNP fellowship program directors from December 2020 to January 2021. Results: The response rate was 60%. There was great variability in the number of CNP positions and CNP tracks offered. The following tracks were identified: 48% EEG dominant, 26% EMG dominant, 22% split equally between EEG and EMG, and 2% and 1% were neurophysiologic intraoperative monitoring and autonomic dominant, respectively. Of the responding institutions, 43% offered a second year of training options to CNP fellows, mainly in conjunction with Epilepsy fellowship, which was pursued by 25% of CNP fellows. Many programs indicated flexibility in their design between different CNP tracks or between CNP and other related training programs based on the available candidates. The median percentage of CNP fellowship positions filled over the last 5 years was 80%, and there was great variation in the recruitment timeline across institutions. Overall, 86% of program directors favored a universal timeline and 71% favored a formal match for CNP. The respondents were split between an independent CNP match (39%) and joining the initiatives of affiliate societies on a standardized process (61%). Conclusions: There is significant heterogeneity in the makeup of the CNP fellowship programs and the recruitment process. The majority of CNP program directors are in favor of standardization of the recruitment process.

AbstractIntroductionMyokymic discharges are classically associated with nerve injury from prior radiation but may occur in other neuromuscular disorders. Using quantitative analysis we aimed to identify the spectrum of conditions in which myokymic discharges are present and determine if there are electrophysiological features that distinguish postradiation from nonradiation causes of myokymia.MethodsWe reviewed the clinical history of all patients examined in our electromyography labs with myokymic discharges recorded from June 2017 to February 2020. Quantitative analysis of each myokymic discharge was performed using a custom MATLAB script, assessing features such as burst frequency, spikes per burst, and burst regularity.ResultsEighty‐eight distinct myokymic discharges (70 patients) were analyzed: 51 postradiation recordings from 35 patients and 37 recordings from 35 nonradiation patients. The diagnostic spectrum of nonradiation cases was diverse, with common causes being median neuropathy (n = 8), cervical (n = 7), and lumbar (n = 5) radiculopathy, and motor neuron disease (n = 5). On quantitative analysis, postradiation myokymia had an increased burst‐to‐silence ratio (median, 0.29; nonradiation, 0.08) and greater peak number (median, 15; nonradiation, 7). Except for one patient with hereditary peripheral nerve hyperexcitability, all patients who had two or more muscles demonstrating myokymic discharges belonged to postradiation group.ConclusionsMyokymic discharges can be seen in diverse neuromuscular conditions; most common in our cohort was chronic median neuropathy. Postradiation myokymia appears to have distinguishing morphological features when quantitatively analyzed compared with nonradiation cases.

Abstract Delayed diagnosis of immune-mediated necrotizing myopathy leads to increased morbidity. Patients with the chronic course without 3-hydroxy-3-methylglutaryl-coenzyme-A reductase-IgG or signal recognition particle-IgG are often challenging to diagnose. Immunotherapy response can also be difficult to assess. We created a statistical model to assist immune-mediated necrotizing myopathy diagnosis. Electrical myotonia versus fibrillations were reviewed as biomarkers for immunotherapy treatment response. Identified were 119 immune-mediated necrotizing myopathy cases and 938 other myopathy patients. Inclusion criteria included all having electrophysiological evaluations, muscle biopsies showing inflammatory/necrotizing myopathies, comprehensively recorded neurological examinations, and creatine kinase values. Electrical myotonia was recorded in 56% (67/119) of retrospective and 67% (20/30) of our validation immune-mediated necrotizing myopathy cohorts, and significantly (P &lt; 0.001) favoured immune-mediated necrotizing myopathy over other myopathies: sporadic inclusion body myositis (odds ratio = 4.78); dermatomyositis (odds ratio = 10.61); non-specific inflammatory myopathies (odds ratio = 8.46); limb-girdle muscular dystrophies (odds ratio = 5.34) or mitochondrial myopathies (odds ratio = 14.17). Electrical myotonia occurred in immune-mediated necrotizing myopathy seropositive (3-hydroxy-3-methylglutaryl-coenzyme-A reductase-IgG 70%, 37/53; signal recognition particle-IgG 29%, 5/17) and seronegative (51%, 25/49). Multivariate regression analysis of 20 variables identified 8 (including electrical myotonia) in combination accurately predicted immune-mediated necrotizing myopathy (97.1% area-under-curve). The model was validated in a separate cohort of 30 immune-mediated necrotizing myopathy cases. Delayed diagnosis of cases with electrical myotonia occurred in 24% (16/67, mean 8 months; range 0–194). Half (8/19) had a chronic course and were seronegative, with high model prediction (&gt;86%) at the first visit. Inherited myopathies were commonly first suspected in them. Follow-up evaluation in patients with electrical myotonia on immunotherapy was available in 19 (median 21 months, range 2–124) which reduced from 36% (58/162) of muscles to 7% (8/121; P &lt; 0.001). Reduced myotonia correlated with immunotherapy response in 64% (9/14) as well as with median creatine kinase reduction of 1779 U/l (range 401–9238, P &lt; 0.001). Modelling clinical features with electrical myotonia is especially helpful in immune-mediated necrotizing myopathy diagnostic suspicion among chronic indolent and seronegative cases. Electrical myotonia favours immune-mediated necrotizing myopathy diagnosis and can serve as an adjuvant immunotherapy biomarker.