Olivary Hypertrophy and Palatal Myoclonus

A 64-year-old woman had sudden onset of clouded consciousness, left hemiparesis, and dysarthria. She was found to have pontine hemorrhage on cranial computed tomography at the local hospital. Medical treatment was begun immediately, with subsequent gradual clearing of consciousness. She was admitted to our hospital 2 months later for the purpose of rehabilitation. Neurologic examination showed that she was alert and not demented. Although mild spastic dysarthria was noted, palatal myoclonus was not detected. Tendon reflexes were moderately exaggerated on the left side, with depressed superficial sensation on the same side. She showed intention tremor in the left arm. Ten months later, cranial magnetic resonance images disclosed an olivary prominence of the medulla on the right side on T1-weighted imaging (Figure, A) and a hyperintense ovoid area of the right inferior olive on T2-weighted imaging (Figure, B). This prompted us to reexamine the palate, and we found a palatal myoclonus with a frequency of 60 to 80 times per minute. The woman continues to have mild left hemiparesis, but lives independently.