Follow-up study of electronystagmographic findings in Friedreich's ataxia patients and evaluation of their relatives.

Fourteen Friedreich patients (F group) who had undergone a first electronystagmogram (E.N.G.) reported in 1978, had the same test 12 to 24 months after the first one. In the second study, there are more patients with bilateral hypoactive caloric nystagmus failure of fixation suppression, ocular dysmetria, irregular pendulum tracking and ocular flutter. These signs are probably most representative of the progression of the disease. Nineteen unaffected relatives of these patients (H group) also had an electronystagmogram but no special "familial" electronystagmographic pattern could be identified. Irregular ocular poursuit, nearly invariable in the F group but absent in the H group, was one of the most important differences between patients and their relatives.