Electrodiagnostic evidence of phrenic nerve demyelination in Charcot-Marie-Tooth disease 1A

Abstract

Objective: To determine whether neurophysiologic findings correlate to clinical respiratory signs or spirometric abnormalities in patients with hereditary motor and sensory neuropathy type 1 (Charcot-Marie-Tooth disease).

Design: A total of 11 patients with hereditary motor and sensory neuropathy type 1A, genetically identified, (age range, 10-58 yr) were included and studied by physical pulmonary examination, chest radiography, respiratory function tests, and bilateral transcutaneous phrenic nerve conduction.

Results: No patient complained of respiratory symptoms or revealed abnormal spirometric or maximal respiratory pressure data, despite a phrenic nerve conduction significantly slower (P < 0.0001; median conduction time, 18.6 msec; 95th percentile, 31.97 msec) than that recorded in the control group of healthy subjects (median, 6.05 msec; 95th percentile, 8.82 msec); the amplitudes of compound muscle action potentials were not statistically different from the controls.

Conclusions: Our study confirms a dramatic phrenic nerve involvement in absence of clinical and laboratory evidence of diaphragmatic weakness; further studies and an adequate follow-up are necessary to discover whether the disease progress might encompass respiratory dysfunction at later stages.