Direct surgery for major artery aneurysm associated with moyamoya disease.

Moyamoya disease is often accompanied by intracranial major artery aneurysms in the posterior circulation which acts as collateral channels in place of the stenotic internal carotid arteries. These major artery aneurysms are considered to have high risk of enlargement and rupture due to increased hemodynamic stress. Direct surgical intervention has been recommended for the treatment of these aneurysms, but the direct approach to them is often difficult due to interference by intertwined abnormal vessels. We have performed direct surgery for seven major artery aneurysms in five patients with Moyamoya disease. Of these three aneurysms located in the anterior circulation were successfully clipped via pterional or interhemispheric approach. Of four posterior circulation aneurysms (two at the junction of the basilar artery and the superior cerebellar artery and two at the P1-P2 junction of the posterior cerebral artery), one was approached via pterional route because collateral vessels in the basal cistern was judged not to be rich on angiograms. However, the operative field was interfered by abundant fragile collateral vessels and it was difficult to reach the distal portion of the basilar artery. In contrast, in the other three cases in which the subtemporal approach was employed, there weren't any problems in exposures of the aneurysms. Our experiences indicate that subtemporal approach is superior than the pterional approach to reach the distal portion of the basilar artery in patients with Moyamoya disease.