Association of Complex Repetitive Discharges with Chronicity and Clinical Symptoms in Radiculopathies (P1-11.011).

Objective: This study aimed to clarify the clinical significance of complex repetitive discharges (CRDs) identified on needle electromyography (EMG) in patients with radiculopathies.

Background: CRDs are incompletely understood spontaneous needle EMG waveforms that can be seen in both myopathic and neurogenic disorders including radiculopathies.

Design/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 1, 2017 and January 1, 2022.

Distinctive clinical features in biopsy-proven nerve large-arteriole vasculitis and microvasculitis.

Vasculitic neuropathy is caused by inflammatory destruction of nerve blood vessels resulting in nerve ischaemia. Nerve vasculitis can be divided into two categories based on vessel size: large-arteriole vasculitis (≥75 µm) and microvasculitis (<75 µm). Herein, we characterize the clinical features of nerve large-arteriole vasculitis in comparison to nerve microvasculitis.

Motor unit potential recruitment reference values in common upper and lower extremity muscles.

Objective: To define reference values for motor unit (MU) recruitment during needle EMG of six commonly examined muscles at low to moderate contraction.

Methods: Needle examination was performed for each muscle in a total of 111 subjects without neuromuscular disorders. Fastest firing rates and recruitment ratios (RRs) were calculated in at least 5 sites within each muscle.

The role of electrodiagnosis in focal neuropathies.

Electrodiagnostic (EDX) testing plays an important role in confirming a mononeuropathy, localizing the site of nerve injury, defining the pathophysiology, and assessing the severity and prognosis. The combination of nerve conduction studies (NCS) and needle electromyography findings provides the necessary information to fully assess a nerve. The pattern of NCS abnormalities reflects the underlying pathophysiology, with focal slowing or conduction block in neuropraxic injuries and reduced amplitudes in axonotmetic injuries.

The utility of electrodiagnostic testing in unprovoked rhabdomyolysis in the era of next-generation sequencing.

Introduction/aims: Rhabdomyolysis is an etiologically heterogeneous, acute necrosis of myofibers characterized by transient marked creatine kinase (CK) elevation associated with myalgia, muscle edema, and/or weakness. The study aimed to determine the role of electrodiagnostic (EDX) testing relative to genetic testing and muscle biopsy in patients with unprovoked rhabdomyolysis in identifying an underlying myopathy.

Methods: EDX database was reviewed to identify unprovoked rhabdomyolysis patients who underwent EDX testing between January 2012 and January 2022.

Association of Complex Repetitive Discharges With Chronicity and Clinical Symptoms in Radiculopathies.

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.

Incidental complex repetitive discharges on needle electromyography.

Introduction/aims: Complex 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.

Methods: A 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.

Electrodiagnostic Characteristics Suggestive of Muscle-Specific Kinase Myasthenia Gravis.

Background And Objectives: Muscle-specific kinase (MuSK) antibody-positive myasthenia gravis (MuSK + MG) is a form of MG with bulbar-predominant symptoms often resistant to conventional treatments. Patients with MuSK + MG may have an electrodiagnostic (EDX) profile distinct from other MG. This study compares EDX features of MuSK + MG with acetylcholine receptor (AChR) antibody-positive MG (AChR + MG) to discern whether any unique EDX pattern exists that can aid in clinical diagnosis.

Clinical and electrophysiological findings in C9ORF72 ALS.

Introduction/aims: Amyotrophic 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).

Assessing electrodiagnostic skills among residents and fellows: Relationships between workplace-based assessments using the Electromyography Direct Observation Tool and other measures of trainee performance.

Introduction/aims: Graduate 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.

Regional anesthesia in patients with Charcot-Marie-Tooth disease: a historical cohort study of 53 patients.

Purpose: Anesthetic management for patients with Charcot-Marie-Tooth disease (CMT) is controversial. Description of the use of regional anesthesia (RA) in patients with CMT is limited. Regional anesthesia has traditionally been avoided because of risk of nerve injury.

Needle Electromyography Waveforms During Needle Electromyography.

Needle electromyography (EMG) waveforms recorded during needle EMG help to define the type, temporal course, and severity of a neuromuscular disorder. Accurate interpretation of EMG waveforms is a critical component of an electrodiagnostic examination. This article reviews the significance of spontaneous EMG waveforms and changes in voluntary motor unit potentials in neuromuscular disorders.

Electromyography Case Examples: Practical Approaches to Neuromuscular Symptoms.

Many neuromuscular complaints are evaluated with electrodiagnostic testing. In practice, physicians must plan the electrodiagnostic study to provide the most useful information addressing patients' symptoms. The approach to each study must be individualized based on the symptoms and findings of each previous result.

Clinical Neurophysiology Fellowship Program Directors Survey on a Standardized Fellowship Match Process: A Call for Action.

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%.

Quantitative analysis of myokymic discharges in radiation versus nonradiation cases.

Introduction: Myokymic 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.

Methods: We reviewed the clinical history of all patients examined in our electromyography labs with myokymic discharges recorded from June 2017 to February 2020.

Diagnostic modelling and therapeutic monitoring of immune-mediated necrotizing myopathy: role of electrical myotonia.

Delayed diagnosis of immunemediated 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.

Brachial and lumbosacral plexopathies: A review.

Diseases of the brachial and lumbosacral plexus are uncommon and complex. The diagnosis of plexopathies is often challenging for the clinician, both in terms of localizing a patient's symptoms to the plexus as well as determining the etiology. The non-specific clinical features and similar presentations to other root, nerve, and non-neurologic disorders emphasize the importance of a high clinical index of suspicion for a plexopathy and comprehensive clinical evaluation.

Two Years of Improved Neurological Function With Nusinersen in a 48-Year-Old Patient With Spinal Muscular Atrophy Type 3.

Introduction: Nusinersen antisense oligonucleotide infusions have been shown to be effective in the treatment spinal muscular atrophy. The majority of the evidence has been collected in young type 1 and type 2 patients, and evidence of efficacy in adult patients is limited.

Case Report: A 48-year-old woman with spinal muscular atrophy type 3 who has received the loading dose and 8 maintenance infusions over an 8-month period.

Sensitivity and specificity of repetitive nerve stimulation with lower cutoffs for abnormal decrement in myasthenia gravis.

Introduction: The sensitivity of repetitive nerve stimulation (RNS) in myasthenia gravis (MG) is dependent on the cutoff for abnormal decrement.

Methods: RNS data of adults with and without MG from 2014 to 2017 were reviewed retrospectively. The maximum reliable RNS amplitude/area decrement before and after exercise from facial, spinal accessory (SA), ulnar, and fibular nerves was recorded.