True posterior communicating artery aneurysm.

Two rare cases of true posterior communicating artery aneurysm are reported. One case was a saccular aneurysm, which was successfully clipped. The other was a case of fusiform trapped aneurysm, and hemiparesis and oculomotor palsy appeared transiently after surgery. In general, this type of aneurysm is included in the category of internal carotid-posterior communicating aneurysm, although some special considerations are necessary in surgical treatment.