Abstract
Objective: We aimed to determine the safety and validity of clipping middle cerebral artery (MCA) aneurysms (MCA-AN) using the distal sylvian approach and securing the MCA horizontal segment (M1) from the dorsal or ventral side, from the viewpoint of the relationship between M1 morphology and surgical technique.
Patients and Methods: We used preoperative digital subtraction angiography or computed tomography angiography to analyze M1 morphology in patients who underwent MCA-AN clipping during a period of approximately nine years. Differences in proximal control during surgery were assessed using the intraoperative videos. Patients with distal, large or giant (maximum diameter ≥ 12 mm), fusiform, thrombosed, or multiple aneurysms were excluded, leaving 119 patients. A convex arcuate M1 or a straight M1 in which the angle between the aneurysm neck and the internal carotid artery bifurcation was ≥ 10° downwards was defined as upward convex. A straight M1 with an angle ＜ 10° upwards or downwards was defined as horizontal. A concave arcuate M1 or a straight M1 with an angle ≥ 10° upwards was defined as downward convex.
Results: Among the patients, 84 (71%), 26 (22%), and 9 (8%) had upward convex, horizontal, and downward convex M1, respectively. The intraoperative videos showed that most of the upward convex and short M1 were secured from the dorsal side. Some horizontal and downward convex M1 needed to be secured from the ventral side, but problems did not arise while securing it beyond the aneurysm.
Conclusion: Securing M1 from the dorsal side of an MCA-AN by clipping via the distal sylvian approach is safe and valid. Proximal control from the ventral side of the M1 can be safely achieved with the same head and body position, even for some patients with horizontal and downward convex M1.
