Bifrontal Interhemispheric Approach Involving Cutting the Superior Sagittal Sinus for Distal Anterior Cerebral Artery Aneurysms

Abstract

The unilateral interhemispheric approach for distal anterior cerebral artery aneurysms presents several risks, such as postoperative venous infarction due to occasional sacrifice of parasagittal bridging vein and postoperative frontal lobe damage due to retraction force. To overcome these risks, we used a bifrontal craniotomy with straight dural incision and cutting of the superior sagittal sinus. We retrospectively reviewed 61 patients (42 unruptured and 19 ruptured A2 and A3 aneurysms) who under aneurysm clipping through bifrontal interhemispheric approach between March 2007 and December 2017. There were 35 A2 aneurysms and 27 A3 aneurysms, and mean size of aneurysms was 5.45 mm. The modified bifrontal interhemispheric approach involved 3 steps: bifrontal craniotomy of centrobasal portion of the frontal bone, ligation and division of anterior one third of the superior sagittal sinus, and approaching the aneurysm via the interhemispheric space. All patients underwent computed tomography on postoperative days 3 and 7 for evaluation of brain retraction damage or venous infarction. Among patients with ruptured aneurysms, 79% had a favorable outcome (Glasgow Outcome Scale score 4 or 5) 6 months after primary subarachnoid hemorrhage; all patients with unruptured aneurysms had favorable outcomes. Surgical outcome was strongly related to preoperative neurologic Hunt and Hess grade. Three patients had poor outcomes due to poor Hunt and Hess grade on admission (grade 3 in 2 patients, grade 4 in 1 patient). Follow-up CT showed that venous infarction did not occur in any of the patients. Modified bifrontal interhemispheric approach may be a safe and effective method for treating A2 and A3 aneurysms with relatively good clinical outcome and no surgery-related complications.