Intention myoclonus of multiple sclerosis, its patho-anatomical basis and its stereotactic relief.

The typical multiple sclerosis case considered here is especially informative from both the standpoint of its clinical course and on the basis of the autopsy findings. The foci responsible for the severe bilateral intention myoclonus of the trunk and limbs are the nerve cell losses in both red nuclei due to extensive and almost complete demyelination. Thereby the triangle of Mollaret between the red nucleus, inferior olives and dentate nucleus is involved as the patho-physiological circuit responsible for myoclonus. Stereotactic coagulation of dentato-thalamic fibres resulted in complete relief of intention myoclonus. With regard to the triggering of fresh demyelinating foci by stereotactic interventions, our point of view is as follows: Although a stereotactic operation introduces the possibility of triggering new demyelinating foci in less than 10% of the cases, such a possibility does not represent an absolute contra-indication to the stereotactic treatment of action myoclonus in multiple sclerosis, if the patient is informed accordingly.