Case Material

Summary It is pointed out that although it is often difficult to make a clinical classification of the hereditary ataxias, Friedreich's ataxia is a fairly well‐defined syndrome. A brief survey is given of the chief symptoms and signs. Such factors as the age at onset, heredity and mode of inheritance may also be helpful in establishing the diagnosis. On the basis of Greenfield's classification of the hereditary ataxias, mainly on a histo‐pathological basis, criteria are set up for a diagnosis of Friedreich's ataxia in the present series. Certain closely related neurological syndromes presenting differential‐diagnostic difficulties are presented. The probands in the present series were sought among the cases treated in hospitals or clinics in Sweden during a 10‐year period, 1951–1960. The final series comprises 56 cases, 36 being probands. The mean age at onset is 8.2 years, and the mean age at onset of walking inability 19.9 years. They are classified according to the degree of physical handicap. A clinical examination is made of 49 of the typical cases, at a mean age of 22.2 years. The genetic aspects and heredity are investigated. A high incidence of consanguineous marriages among the parents is found, as well as a number of secondary cases among the sibs and other relatives.