Electrophysiological study (EEG, VEPs, BAEPs) in patients with Charcot Marie Tooth (type HMSN I) disease

A laboratory investigation consisting of EEG recordings, BAEPs and VEPs evaluation as well as estimation of the facial nerve distal latency was performed in 9 patients who had Charcot Marie Tooth (type HMSN I) disease. 3 patients showed VEP's abnormalities (2 of them had prolonged P100 latency and one had an abnormal interocular latency difference). Another patient showed an upper normal limit value in the interocular latency difference. Abnormal BAEPs were found in 8 patients (one had I-III/IPLD prolonged, 2 of them had the latency of wave I prolonged and the remaining 6 had no readable or repeatable responses unilaterely or bilaterally). 7 out of 9 patients had the facial nerve distal latency prolonged, without any evident clinical facial weakness. Abnormal EEG recordings were found in 2 of all tested patients. Our results provide some evidence that in Charcot Marie Tooth disease the involvement of the II, VII and VIII nerves is more frequent than clinically expected and is probably related to a demyelinated process.