Search

• MScanFit shows motor unit loss in spinal cord injured patients. • Muscle velocity recovery cycles show muscle membrane depolarization suggesting denervation of paralyzed muscles following spinal cord injury (SCI). • When planning rehabilitation after SCI examination of peripheral nervous system should be considered. To examine the peripheral nervous system (PNS) in spinal cord injured (SCI) patients using two novel methods: (1) MScanFit MUNE; a motor unit number estimation method detecting motor unit loss and (2) muscle velocity recovery cycles (MVRCs) measuring muscle membrane properties which has previously shown depolarization of the muscle membrane in denervated muscles. Thirty chronic SCI patients (lesion above Th10) and twenty-five gender –and age matched healthy controls (HC) were examined. MScanFit was recorded from peroneal nerve to anterior tibial muscle (TA) and tibial nerve to abductor hallucis muscle after excluding localized mononeuropathies. MVRCs were recorded from TA. Nerve conduction studies showed mononeuropathy in 8 patients (27%) (sciatic (2), -or peroneal nerve (6)). SCI patients had in average reduced motor unit number compared with HC and prolonged muscle refractory period and reduced supernormality. A high prevalence of nerve lesion and a diffuse affection of the PNS following SCI are highly relevant findings that should be accounted for when planning neurorehabilitation for persons living with SCI. [ABSTRACT FROM AUTHOR]

• Muscle velocity recovery cycles (MVRCs) show in vivo evidence of depolarized muscle membrane in neurogenic muscles in humans. • MVRC parameters correlate to disease severity and muscle strength but not to disease duration. • MVRC is a useful technique for revealing disease mechanisms in neuromuscular disorders. To examine muscle membrane properties in neurogenic muscles using Muscle Velocity Recovery Cycles (MVRCs). 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/EMG (n = 9) and other disorders (n = 6) using NCS/EMG and neuroimaging results. Strength in anterior tibial 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 anterior tibial muscle. This provided parameters of muscle relative refractory period (MRRP) and early supernormality (ESN) and late supernormality (LSN). The results were compared with 29 age-matched healthy control subjects. MRRP was prolonged and ESN and LSN were reduced in neurogenic muscles. MRRP, ESN and LSN correlated to MRC and incidence of spontaneous activity but not to motor unit potential parameters or disease duration. 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. MVRCs appear to be a useful technique for revealing disease mechanism in a broad range of neuromuscular diseases. [ABSTRACT FROM AUTHOR]