iii. Anterior choroidal artery

Preservation of the anterior choroidal artery is essential in order to avoid postoperative hemiplegia. On this basis, precision of segmental occlusion offers obvious advantages. Should the origin of the anterior choroidal artery prove impossible to save, the procedure should be abandoned.

Apart from carotid side branches, another important concern with all deconstructive procedures is postoperative early or late ischemia. Unselective, abrupt occlusion of the internal carotid artery is known to carry a 26% risk of cerebral infarction and 12% risk of death [88]. A balloon occlusion test should always be performed when such an approach is contemplated. This entails inflation of a nondetachable balloon at the site of the intended occlusion and subsequent clinical and angiographic evaluation of hemispheric collateral circulation [89, 90]. However, one should always keep in mind that—in the setting of a subarachnoid hemorrhage—results of a balloon occlusion test can be misleading. This is due to the fact that a balloon occlusion test does not take into account the hemodynamic effects of a posthemorrhagic vasospasm which may complicate such cases [16].

For patients who fail a balloon test occlusion, surgical bypass should be contemplated. Traditionally, this is in the form of an artificial communication between the superficial temporal and the middle cerebral artery with or without an interposed vascular graft (radial artery or saphenous vein) (STA-MCA bypass) [16, 58]. In the case a graft is to be used, this is termed as a high-flow bypass and ensures significantly better results [91]. As a matter of fact, there are authors recommending high-flow bypasses as a primary mode of treatment for blister aneurysms. However, experts in the field seem skeptical advocating that a high-flow bypass should never be thought of as complete substitute for normal carotid artery supply, quoting an 80% rate of postoperative complications, including graft occlusion and vasospasmrelated cerebral infarction [41]. Additionally, surgical bypass in patients with severely atherosclerotic vessels typically requires antiplatelets, a feature that only adds to the overall risk.
