Myoclonus and Ataxia Occuring in a Family.

[n 1914 J. Ramsay Hunt described the syndrome he called 'dyssynergia cerebellaris progressiva'. He regarded this condition with its well-defined cerebellar symptoms as an 'organic disease caused by degeneration of certain special structures of the cerebellar mechanism'. In 1921 at an annual meeting of the American Neurological Association, he presented a further six cases which combined the symptoms of dyssynergia cerebellaris progressiva with myoclonus and epilepsy. Only two of hispatients were related. Both patients, twins, had in addition Friedreich's ataxia, and of these, one came to necropsy. Pathological studies on this 36-year-old male showed primary atrophy of the efferent dentate system of the cerebellum with 'considerable diminution in number and extensive atrophy of the cells of the dentate nucleus with secondary atrophic changes in the superior cerebellar peduncles', as well as the typical spinal lesions of Friedreich's ataxia. Ramsay Hunt now called this syndrome 'dyssynergia cerebellaris myoclonica'. Not all his cases had epilepsy. Since then, several authors have described examples of this syndrome with varying emphasis on the features mentioned previously. In practically all the reported series the syndrome appeared sporadically, and included epilepsy. Recently, Gilbert, McEntee, and Glaser (1963) have described four cases occurring in a family without epilepsy, under the title of 'familial myoclonus and ataxia'. A further four familial example3 are presented here, together