Longitudinal conduction studies in hereditary motor and sensory neuropathy type 1

Abstract
Motor conduction studies were performed serially in 10 patients, ages 10–62 years, with clinical and electrophysiological criteria of hereditary motor and sensory neuropathy type 1 (HMSN-1) over periods of 11–19 years. Median nerve conduction velocity (MNCV) and distal motor latency showed no significant change on serial studies. Mean median compound muscle action potential (CMAP) amplitude values, however, decreased 66% in 8 patients. Observed clinical progression in HMSN-1, over prolonged periods of time, was not associated with MNCV slowing. However, CMAP amplitude reduction, reflecting progressive axonal loss, correlated with clinical deterioration.