Introduction: a study was conducted in the Valle d'Aosta Region, Italy, (115270 inhabitants) to determine the prevalence of hereditary ataxias (HA) and hereditary spastic paraplegias (HSP), and the degree of disability they cause.
Methods: we identified all patients with suspected HA or HSP referred from 1981 to 1991 to in- and out-patient departments, EEG, EMG, and CT-scan services, and centres for the handicapped. Harding's criteria were followed for diagnosis and classification.
Results: at the prevalence day, 17 patients were alive, with a prevalence ratio of 14.8/100,000 population. There were 2 cases of Friedreich's ataxia (FA), 1 of early onset cerebellar ataxia with retained tendon reflexes (EOCA), 1 of autosomal dominant cerebellar ataxia (ADCA), 8 of sporadic idiopathic late onset cerebellar ataxias, and 5 of HSP.
Conclusions: epidemiological studies on HA and HSP show highly variable prevalence ratios, which could be due in part to the inclusion of sporadic cases. FA, EOCA and ADCA have similar prevalence ratios in most studies.