O-26 Muscle velocity recovery cycles in neurogenic muscles. Issue 7 (July 2019)

• Record Type: Journal Article
• Authors: Witt, Agnes; Kristensen, Rikke Søgaard; Fulgsang-Frederiksen, Anders; Pedersen, Thomas Holm; Finnerup, Nanna Brix; Kasch, Helge; Tankisi, Hatice
• Is Part Of: Clinical neurophysiology. Volume 130:Issue 7(2019:Jul.)
• Page Start: e30
• Publication Date: 2019-07
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2019.04.342
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Background: Muscle Velocity Recovery Cycles (MVRCs) is a simple and fast method offering indirect measure of muscle membrane properties in vivo. MVRCs has been used to provide information about muscle membrane abnormalities in various myopathies and muscle channalopathies. The aim of this study was to examine muscle membrane properties in neurogenic muscles using MVRCs. Material and methods: Forty-seven patients referred to Nerve Conduction Studies (NCS) and Electromyography (EMG) for peroneal nerve entrapment neuropathy were prospectively included. The patients were categorized as peroneal nerve entrapment neuropathy across knee ( n = 22), L5-radiculapathy ( n = 10), normal NCS and EMG ( n = 9) and other disorders ( n = 6) using NCS/EMG and neuroimaging results. Strength in tibialis anterior (TA) muscle was measured by Medical Council Scale (MRC) and disease duration was recorded. In addition to conventional NCS/EMG, all subjects were examined with MVRCs in TA. This provided parameters of muscle relative refractory period (MRRP) and early supernormality (ESN) and late supernormality (LSN). The results were compared to 29 age-matched healthy control subjects. Results: MRRP was increased and ESN and LSN were reduced in neurogenic muscles. MRRP, ESN and LSN correlated to MRC, incidence of spontaneous activity and motor unit potential parameters, but not to disease duration. Conclusions: MVRC changes provide in vivo evidence of depolarization in intact human muscle fibres that could underlie reduced muscle excitability and hence weakness in neurogenic muscles. MVRC appears to be a useful technique for revealing disease mechanism in a broad range of neuromuscular diseases.