ABSTRACT
Autosomal dominant cerebellar ataxias are characterized by variable degrees of cerebellar and brainstem dysfunction. Patients usually present with progressive cerebellar gait and the associated signs define three groups of phenotypes according to Harding’s clinical classification (Harding, 1993). ADCA type I is the most common group and variably combines cerebellar ataxias and dysarthria with ophthalmoplegia, pyramidal or extrapyramidal signs, amyotrophy and rarely dementia (Table 1). ADCA type II combines cerebellar ataxia with macular dystrophy and other neurological signs, whereas type III represents pure cerebellar ataxia with no or very few associated signs. However, the phenotype (e.g. the combination of neurological signs) cannot be predicted from the genotype, except for ADCA type II or SCA7, which is associated with visual loss due to macular degeneration. Even in ADCA type II there are lateonset cases in which visual loss can be missing. Mean age at onset is 35 years but with a wide range, from birth up to 70 years. The disease progression is unremitting and no curative treatment exists today. Psychological support should be part of treatment of these disabling diseases, in addition to medical care, often limited to physiotherapy.
