[Three cases of involuntary movements following pontine hemorrhage]

We reported three cases with involuntary movements following pontine hemorrhage. All cases had various symptoms indicating brain-stem lesions, but the consciousness and motor functions were not severely disturbed. CT scans showed a small hematoma localized in unilateral pontine tegmentum in all cases. Intention tremor developed six to ten months after the hemorrhage when the initial neurological symptoms were almost relieved. Electromyogram (EMG) showed a rhythmic 3-4 Hz alternating or synchronized tremor pattern which was induced by finger-nose test and arm stretching. In one case which had showed bilateral horizontal gaze palsy indicating bilateral PPRF involvement in the acute stage, spontaneous vertical nystagmus was observed when the tremor developed. Electronystagmogram (ENG) and its differential calculus showed a pendular nature of the eye movement. This abnormal eye movement did not disappear while the patient was asleep. This case also developed a palatal myoclonus in the chronic stage. Magnetic resonance images (MRI's) obtained one to three years after the hemorrhage revealed a lesion localized in hemipontine tegmentum. The responsible lesion of these involuntary movements was thought to be located in pontine tegmentum from the MRI findings. The functional Prognosis of small hemorrhage in unilateral pontine tegmentum is generally good, but care should be taken for the possibility of late development of various types of involuntary movement.