Complex Repetitive Discharges: A Sign of Motor Axonal Reinnervation?

Andreas Posa,Malte E Kornhuber,Alexander Emmer,Izabela Niśkiewicz,Frank Hanisch

doi:10.3390/brainsci10060349

Andreas Posa, Malte E Kornhuber + Show 3 more

Open Access

https://doi.org/10.3390/brainsci10060349

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Journal: Brain sciences	Publication Date: Jun 5, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: Martin Luther University Halle-Wittenberg

Abstract

Complex repetitive discharges (CRDs) are poorly understood phenomena in needle electromyography (EMG) recordings. The data presented here suggest that CRDs may mainly be a sign of motor unit reinnervation. EMG “video” data of 108 CRDs from neurogenic (ND, n = 39) and myogenic (MD, n = 14) disorders were retrospectively analyzed for cycle duration, potential-free time intervals, spike components (SC), maximum amplitudes, blockade, and increased jitter. CRD-SC in ND disorders (9.3 ± 7.8) outnumbered those in MD disorders (6.3 ± 6.2). The CRD cycle duration was correlated with SC and silent periods (p each < 0.000001). Blockade was observed in 36% and increased jitter in 27% of the CRDs. A higher number of CRD-SC in ND vs. MD fits the known differences in motor unit dimensions. Blockade and increased jitter are known features of diseased neuromuscular junctions, such as during reinnervation. The SC patterns of single CRD cycles resemble reinnervation potentials. Thus, CRDs may result from myo-axonal re-excitation in sprouting motor units. The purpose of this investigation was to better understand the circumstances under which CRDs may occur and eventually to contribute to the understanding of their pathogenesis.

Highlights

Pathological spontaneous activity in needle electromyography (EMG) investigations is frequently composed of single potential components, such as fibrillation potentials, positive sharp waves or high frequency discharges with or without variation in amplitude and intercomponent intervals
complex repetitive discharges (CRDs) have been observed in different neuromuscular disorders, such as metabolic myopathies, muscular dystrophies, and motor neuron disorders, as well as in the lesions of nerve roots, nerve plexuses or peripheral nerves [2,3]
Proposed that CRDs mayon besingle generated from one muscle fiber Trontelj to the

Summary

Introduction

Pathological spontaneous activity in needle electromyography (EMG) investigations is frequently composed of single potential components, such as fibrillation potentials, positive sharp waves or high frequency discharges with or without variation in amplitude and intercomponent intervals. Not frequent is pathological spontaneous activity that consists of two or more spike components that cyclically discharge with more or less stable time intervals over time. CRDs have been observed in different neuromuscular disorders, such as metabolic myopathies, muscular dystrophies, and motor neuron disorders, as well as in the lesions of nerve roots, nerve plexuses or peripheral nerves [2,3]. Their onset and offset are usually abrupt. The onset may be triggered by needle insertions [3,4,5]

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