Hypertrophy of the inferior olivary nucleus. A clinico-pathological observation.

The clinico-pathological findings in a 61-year-old man, who suffered from branchial and skeletal myoclonus, appearing six months after a brainstem infarction are reported. Of all the drugs which are usually thought to be effective in the treatment of myoclonus, only valproic acid brought some relief. The necropsy revealed bilateral hypertrophy of the olives, together with bilateral pontine tegmental and rubral infarctions, without involvement of the olivary pathway.