Unruptured large intracranial aneurysms in patients with transient cerebral ischemic episodes.

This report analyzes the treatment of six patients with transient cerebral ischemic episodes in combination with large unruptured aneurysm. Priority treatment of the symptomatic lesions had to be delayed in five cases because the large aneurysms were ipsilateral to stenoses of the internal carotid artery. The hemodynamic effect of surgery on the compromised cerebral circulation was pre-examined with digital subtraction angiography and technetium-99m ((99m)Tc) single photon emission computed tomography. The data were correlated to aneurysm location and anatomical territory of the transient ischemic episodes. Only one patient showing a severe carotid stenosis contralateral to the large aneurysm, with decreased technetium uptake in the symptomatic hemisphere, required surgical correction of the stenosis first. In five patients, areas of reduced (99m)Tc uptake were mostly found within vascular boundary zones with angiographically verified effective collateral circulation. Clipping of the large aneurysms in these patients ipsilaterally to the stenotic lesion or on the anterior communicating artery as first option did not substantially increase the risk of subsequent stroke.