Compressive bilateral peroneal neuropathy: serial electrophysiologic studies and pathophysiological remarks

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Abstract
A case of bilateral common peroneal neuropathy following prolonged squatting is reported. Serial peroneal conduction velocities with analysis of compound muscle action potential (CMAP) amplitude, area and duration performed at Days 1, 2, 5, 7, 14, 21, 37, 80 showed conduction block localized at the fibular head which lasted 14 days and paralleled clinical conditions. Axonal loss coexisted as indicated by amplitude reduction of CMAP from peroneal nerve stimulation at the ankle which reached the lowest values at Day 7. Excessive temporal dispersion, as indicated by abnormal increased duration of the CMAP from stimulation above the fibular head, was never detected. Conduction velocity in the segment across the fibular head was reduced as long as conduction block was present, due to preferential block of large diameter, fast conducting, fibers. The rapid resolution of conduction block and the absence of temporal dispersion suggest that compressive conduction block is not necessarily due to demyelination. Mechanical factors or ischemic-metabolic mechanisms might play a role.