Cerebellar hemorrhage after coil embolization for a ruptured vertebral dissecting aneurysm. 
We present a case of ruptured vertebral dissecting aneurysm that exhibited cerebellar hemorrhage after successful embolization of the vertebral artery including the dissected site.  A 59-year-old man suffered a sudden onset of severe occipital headache when he looked up.  Computed tomography demonstrated subarachnoid hemorrhage.  Angiography revealed a right vertebral dissecting aneurysm distal to the posterior inferior cerebellar artery.  Endovascular embolization of the aneurysm was performed with preservation of the posterior inferior cerebellar artery.  The next day, the patient suffered a cerebellar hemorrhage in the vermis.  The intracranial pressure was controlled by external ventricular drainage.  The patient was discharged with mild cerebellar ataxia and bilateral abducens nerve palsy.  In a case of vertebral dissecting aneurysm distal to the posterior inferior cerebellar artery, blood circulation in the vertebral arterial system may change after embolization of the aneurysm.  In our case, the preserved posterior inferior cerebellar artery might have been hemodynamically stressed postoperatively, resulting in cerebellar hemorrhage.  Therefore, strict control of blood pressure is essential in the acute stage after occlusion of the aneurysm.