" THE classification of the spinocerebellar ataxias has long been a matter of dispute, for neither the clinical features nor the findings at autopsy provide a satisfactory basis for the isolation of distinct categories."’There can be little doubt that the hereditary ataxias and paraplegias are one of the most nosologically confused groups of genetically determined neurological disorders and it has been suggested that there are as many classifications of them as there are authors on the subject. Unfortunately, the vast literature on the hereditary ataxias consists predominantly of case-reports of single cases or families and many cases of what seem to be the same clinical syndrome have been given different labels by different authors, even when patients are members of the same family. 2-4 Attempts to classify the inherited ataxias have been based on their neuropathological features or specific clinical signs such as tendon reflex changes. Such schemes are rarely helpful in management and, again, often result in assignment of members of the same family to different disease categories. 5-8