[Involvement of the optic nerve in neural muscular atrophy].

Visual evoked potentials (VEP) were investigated in 12 members of a family with Charcot-Marie-Tooth disease, 7 of whom showed manifest clinical signs of the disease. The mean value of the latency P100 of VEP in the 12 patients did not differ significantly from the value in normal controls, nor did the values in members with considerably reduced nerve conduction velocities differ significantly from those in members with normal nerve conduction velocity. Among the investigated members of the family, however, there was a significant difference in mean P100 latency between family H.G. with no clinical signs of the disease and the family of the twin brother, F.G. with clear clinical and neurographic signs of HMSN I. The divergent opinions given in the literature may be explained by heterogeneity, as well as an extreme expression of the inherited defect and a combination of two independently inherited diseases.