Surgically treated aneurysm of the trunk of the persistent primitive trigeminal artery--case report.

A 62-year-old man presented with a very rare cerebral aneurysm arising from the trunk of the persistent primitive trigeminal artery (PPTA) manifesting as subarachnoid hemorrhage. Angiography showed a saccular aneurysm at the curved mid-section of the trunk of the left PPTA of the adult type. The patient underwent surgery via the left subtemporal approach, and the aneurysm was successfully eliminated by clipping without sequelae. Aneurysm formation at this point was probably due to hemodynamic stress. The perforating arteries from the PPTA may be important in supply of the hindbrain, so PPTA patency should be preserved if possible.