[The importance of neurophysiology and computerized tomography for diagnosis of cerebellar ataxia with late onset].

Twenty patients diagnosed as suffering from autosomal dominant or idiopathic late onset cerebellar ataxia were investigated clinically, by means of neurophysiological tests (blink reflex, BAEP, SEP, MEP, VEP) and CT scan. Twelve patients presented with a pure cerebellar ataxia (CA) after a disease duration of at least five years (mean disease duration ten years). Eight patients presented with additional non-cerebellar signs of involvement; hence the disease was classified as olivo-ponto-cerebellar atrophy (OPCA). Eight of the twelve patients with CA already exhibited pathological results in at least one of the neurophysiological tests as subclinical evidence of a lesion beyond the cerebellum. Three of these patients showed an atrophy of brainstem structures in addition to the cerebellar atrophy. The ongoing prospective follow-up study will show whether these signs of subclinical involvement of non-cerebellar pathways are predictive for the development of a multi-system disorder in terms of OPCA. In cases of CA with subclinical signs of a lesion beyond the cerebellum there may be no clinical, non-cerebellar signs for a multisystem disorder even within a disease duration of up to fifteen years.