["True" posterior communicating artery aneurysm presenting the abducens nerve palsy].

Most of "so-called" posterior communicating artery aneurysms previously reported, originated from the internal carotid-posterior communicating junction. Aneurysms arising from the posterior communicating artery itself are very rare. The abducens nerve palsy caused by cerebral aneurysm is also very rare. We are reporting a case with the saccular aneurysm arising directly from the distal half of the posterior communicating artery presenting the abducens nerve palsy. This 73-year-old woman who had no treatment with hypertension for several years was admitted for sudden onset of severe headache, vomitting and unconsciousness on March 1, 1984. She opened her eyes when addressed and had disorientation, urinary incontinence, right-hemiparesis and left-abducens nerve palsy. A 4-vessel angiography revealed the saccular aneurysm originating directly from the distal half of the posterior communicating artery. The patient underwent left-frontotemporal craniotomy on the 27th day after subarachnoid hemorrhage under Hunt & Kosnic Grade 3. The aneurysm originated directly from the distal half of the posterior communicating artery and directed inferior-posterior-laterally below the oculomotor nerve. The neck was successfully clipped. Immediate post-operative course was uneventful until the 7th day after surgery. On the 8th day she had hypertensive intraventricular hemorrhage and expired. The autopsy could not be obtained. The saccular "true" posterior communicating artery aneurysm with isolated unilateral abducens nerve palsy as seen in our case has not been reported. Considering the operative findings, we thought the aneurysmal dome contacted directly with the abducens nerve.