[Monoballism associated with internal carotid artery occlusion : a case report].

A 62-year-old man was admitted to our hospital with abrupt onset of monoballism in the left arm. Brain MRI showed a hemorrhagic lesion in the right subthalamic nucleus. MRA demonstrated occlusion of the right internal carotid artery occlusion. Cerebral angiogram indicated a leptomeningeal anastomosis to the right middle cerebral artery from the right posterior cerebral artery. SPECT with 99mTc-HMPAO demonstrated the reduction of cerebral blood flow in the right frontotemporal region. Right superficial temporal artery-middle cerebral artery anastomosis was performed 7 months after onset. Monoballism disappeared after surgery and the patient had a good clinical course during the postoperative period. Monoballism associated with internal carotid artery occlusion is rare, and we were able to show the subthalamic nucleus lesion with MRI soon after onset. We considered that the reason for this hemorrhage in the subthalamic nucleus was the hemodynamic stress to the posterior cerebral artery area caused by the ipsilateral occlusion of the internal carotid artery.