[Myorhythmia emerging on day 15 in a case of an infarction in the midbrain-pontine tegmentum]

A 72-year-old woman was admitted to our hospital because of dysarthria, dysstasia, and diplopia. Examination demonstrated wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) syndrome, dysarthria, truncal ataxia, and dysmetria of the four limbs. Cranial MR images demonstrated an acute infarct in the paramedian, lower midbrain-pontine tegmentum. Peduncular hallucinosis was observed during the first several days of hospitalization. Myorhythmia (skeletal myoclonus) appeared as early as day 15 and has persisted to date, with a frequency of approximately 1.5 Hz on the head and chin, and 3.5 Hz on the left upper extremity. Cranial MR images 5 months after onset demonstrated bilateral inferior olivary hypertrophy, while palatal tremor appeared later. Only a limited number of case reports are available in which myorhythmia emerged as early as in our case after the onset of a brain infarct.