Clip Ligation of Midsegment M1 Artery Aneurysm through a Lateral Supraorbital Approach: 2-Dimensional Operative Video

Lenticulostriate middle cerebral artery (MCA) aneurysms are rare and often involve perforating vessels, making endovascular treatment difficult. When projecting superiorly, aneurysm rupture can likely cause intraparenchymal hemorrhage in basal ganglia. Consequently, surgical clip ligation requires control not to aggressively elevate the frontal lobe to avoid intraoperative injury. We report a case of a growing right midsegment MCA aneurysm treated with clip ligation via a lateral supraorbital approach (LSO). The patient is a 71-year-old female found to have a 4 mm × 3 mm right M1 aneurysm in 2014 on workup for headaches. Subsequent imaging demonstrated aneurysm growth to 6 mm × 3.1 mm with peaked-dome appearance. The growth and location of the aneurysm led us to recommend open surgical treatment; the patient provided informed written consent to proceed. We performed a standard right-sided LSO approach.¹ Microdissection was performed to split the sylvian fissure distally and then proximally to expose the MCA on either side of the aneurysm. Dissecting the aneurysm revealed a perforating artery at the proximal neck. Using minimal frontal lobe dynamic retraction, microsurgical clip ligation was performed. We ensured the clip was placed in line with the MCA trunk to avoid kinking the parent artery and subsequent stroke. Intraoperative micro-Doppler and indocyanine green injection confirmed the patency of vasculature. Postoperative angiogram confirmed complete aneurysm ligation. The patient clinically did well and was discharged home on postoperative day 2. Our video demonstrates safe and effective surgical treatment of a rare aneurysm² through a small LSO craniotomy approach (Video 1).