DIAGNOSTIC-APPROACH TO CEREBELLAR-ATAXIA

The first step in diagnosing cerebellar ataxia is to distingguish between focal cerebellar disease (tumor, abscess, ischaemia, haemorrhage, focal demyelinisation) and non-hereditary or hereditary system disorders of the cerebellum. This first step is achieved by the use of computed tomography or magnetic resonance imaging. The non-hereditary ataxias are subdivided into symptomatic ataxias (toxic, paraneoplasic, heat injury, vitamin deficiency, endocrinological or inflammatory) and idiopathic ataxias, the cause of which remains unknown. Differentiation is made by careful recording of the history and by a number of laboratory investigations. If hereditary ataxia is suspected, the further diagnostic procedure should be guided by the age of onset of the ataxia. In ataxic children under 5 years the most probable diagnosis is congenital ataxia or ataxia with a known metabolic cause. Potential metabolic causes must be sought for with the help of a number of laboratory tests. Friedreichs ataxia is the most frequent ataxia with an onset between 5 and 25 years, followed by early-onset cerebellar ataxia with retained tendon reflexes. Both diagnoses are made clinically, after metabolic defects have been excluded. Hereditary ataxia starting in adult life is usually inherited autosomal-dominant.