Visual and brainstem auditory evoked potentials in hereditary motor-sensory neuropathy.

Visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) were recorded in 57 children and adults with hereditary motor-sensory neuropathy (HMSN); 37 of them were diagnosed as type I (demyelinating) and 20 as type II (axonal). None of the patients presented central nervous system involvement. The results were compared with VEP and BAEP records of 12 adults with Guillain-Barré syndrome (GBS) and 40 healthy controls. Above 30% of all patients with HMSN I showed delayed latency of the VEP. These abnormalities were less expressed in HMSN II. Abnormal BAEP were observed in almost 50% of patients with HMSN I and HMSN II with nearly the same frequency in both types but more pronounced in HMSN I. The most common feature was prolongation of the I-III interpeak latency (JPL). The VEP and BAEP changes could be present simultaneously in the same patient (mainly in HMSN I) or separately. More often the abnormalities were observed in the adult patients. Normal VEP and BAEP values were present in all patients with GBS. The results strongly suggest the subclinical optical and auditory pathways involvement in HMSN patients.