Surgical Treatment for Superior-projected Aneurysms at the Proximal (M1) Segment of the Middle Cerebral Artery

Surgical treatment for the cerebral aneurysms of the proximal (M1) segment of the middle cerebral artery, especially those that project superiorly, carries a high risk of infarct caused by damage of perforating arteries. Between January 2004 and November 2009, of 114 patients with MCA aneurysms treated surgically in our hospital, 11 patients with aneurysms of the proximal MCA were diagnosed on the basis of angiographic or surgical findings. Among them, 8 patients had aneurysms projected superiorly. All patients underwent surgery via fronto-temporal craniotomy and trans-sylvian approach. Four patients with ruptured aneurysms underwent emergency surgery within 72 hours of the insult. Motor evoked potential (MEP) was monitored during surgery in the latest 2 patients. We reviewed retrospectively 8 patients with such aneurysms treated by direct surgery. The average age in our patient population was 64.3 years (range, 56-81 yr). There were 2 men and 6 women. The average size of aneurysms was 8.1 mm (range, 3-25 mm). Four patients had ruptured aneurysms. Intracerebral hematoma was recognized on computer tomographic (CT) scan in 2 patients with ruptured aneurysms. Neck clipping was performed in 7 patients and wrapping in 1 patient. STA-MCA bypass was performed for the patient with giant aneurysm. Temporary occlusion of the M1 segment was required in 2 patients, including the patient with giant aneurysm. CT scans after surgery revealed cerebral infarction in the territories of the perforating artery from the M1 segment in 3 patients, and aphasia remains in 1 of the 3 patients. At 3 months after surgery, 5 patients made a good recovery (GR), 2 had a moderate disability (MD), and 1 a severe disability (SD), according to Glasgow Outcome Scale (GOS). All of the unruptured aneurysms made GR, though 1 patient presented with cerebral infarction. The aneurysms of the M1, which project superiorly, represent one of the most complicated aneurysms. Understanding the relationship between the perforating arteries arising from the M1 segment and the aneurysm neck should allow surgeons to avoid many postoperative ischemic complications.