Clinical Outcome of Surgical Clipping for Anterior Choroidal Artery Aneurysm

The surgical clipping of anterior choroidal artery (AChA) aneurysms has an increased risk of ischemic complications owing to the critical territory that is supplied by the AChA. We retrospectively analyzed 27 patients (28 AChA aneurysms; 10 men, 17 women; mean age: 57.6 years), including 16 patients with subarachnoid hemorrhages, who were treated with surgical clipping between April 1990 and October 2013. At our institution, we have been performing intraoperative monitoring of motor evoked potentials (MEPs) and indocyanine green videoangiography (ICG-VAG) since 2008. On the basis of preoperative cerebral angiography and intraoperative findings, we created the following new classification system of AChA aneurysms, according to the AChA branching point: A, artery type (4, 14.3%); B, neck type (19, 67.8%); C, dome type (1, 3.6%); and D, duplication type (4, 14.3%). Clinical outcomes were evaluated by the modified Rankin Scale at the last follow-up examination. There were three patients with AChA syndrome after clippings that were performed without MEP/ICG-VAG. However, after the introduction of MEP/ICG-VAG, the outcomes of surgical clippings significantly improved (p = 0.005). Three patients had incomplete clippings because the AChA branched from the aneurysmal neck and dome (types B, C, and D). Furthermore, in three cases, we could not detect the duplicated AChA (type D) with preoperative angiography. In some cases with AChA aneurysms, in which complete clipping is difficult because of the AChA branching type, MEP/ICG-VAG monitoring and a precise understanding of the AChA classification (branching pattern) are necessary for good outcomes.