The Dentato-olivary Pathway

THE SIGNIFICANCE of a pathway directly linking the dentate nucleus of the cerebellum and the contralateral inferior olive has been revealed by clinicoanatomical study of the phenomenon of palatal myoclonus.1-8 The lesion which has been most constantly demonstrated in cases of palatal myoclonus (as in rhythmic skeletal myoclonus) is a specific hypertrophic (presumably transynaptic) degeneration of the inferior olive. This hypertrophic degeneration, with very few exceptions,8,9is associated with a primary lesion in the ipsilateral central tegmental tract1,10-12or the contralateral dentate nucleus.3,13-14 In the first attempt to explain these associations, Guillain and Mollaret4proposed a triangular relationship among the red nucleus and inferior olive on one side and the contralateral dentate nucleus. However, since no lesion of the olivodentate fibers within the inferior cerebellar peduncle has been associated with palatal myoclonus or hypertrophic olivary degeneration, it subsequently became apparent that this side of