Therapeutic Strategies of Middle CerebralArteryM1 Trunk Aneur

Objective : This study was designed to define the clinical characteristics and to establish the therapeutic strategies for treating aneurysms located at the M1 trunk of the middle cerebral artery (MCA). Methods : During the past 30 years from September 1976 to December 2006, 47 (6.2% of the 755 treated MCA aneurysms) consecutive patients with M1 aneurysms were treated at our institute. We retrospectively reviewed the database and imaging studies of these 47 patients for analysis. Nine patients (19.1%) were male and 38 (80.9%) patients were female. The mean age was 51.7 years (range: 381 years). Thirty-three (70.2%) patients had ruptured lesions: 3 patients were Hunt and Hess Grade I, 16 patients were Grade II, 7 patients-were Grade III, 4 patients were Grade IV and 3 patients were Grade V. Intracerebral hemorrhage was identified in 9 patients on the initial computed tomograph images. Fourteen patients had unruptured lesions. The diameters of the aneurysms were 25 mm in 2 patients. The mean diameter of the aneurysms was 5.1mm (range: 2.029.0mm). Eleven patients (23.4%) had multiple aneurysms. The repair methods for the aneurysms were microsurgery in 42 (89.4%) patients (clipping: 36, wrapping: 6, aneurysm resection and suture: 1) and coiling in 5 patients. The mean posttreatment follow up period was 45.5 months. The clinical outcome was assessed using the Glasgow Outcome Scale. The therapeutic results of lesion repair, the long-term clinical outcome and the causes of an unfavorable outcome were also analyzed. Results : The overall outcome was favorable in 39 (82.9%) patients (excellent: 32, good: 7) and unfavorable in 8 (17.1%) (fair: 6, poor: 1, dead: 1) patients. The major causes of an unfavorable outcome were the initial insults. Seven patients suffered from a delayed ischemic deficit, and 3 of them were left with a permanent deficit. Surgery-related complications occurred in 8 patients (cerebral infarction: 6, intracerebral hemorrhage: 2) and 3 were left with a permanent deficit. The angiographic results of coiling were complete packing in 3 (60%), a neck remnant in 1 (20%) and incomplete packing for 1 (20%). There was no coiling-related complication. Conclusion : In our series, M1 aneurysms had characteristics of a female predominance, the patients more often presented with intracerebral hemorrhage, and a high risk of postoperative ischemic complication. Due to the small size, wide neck and location at the branching site, M1 aneurysms can be treated with surgery rather than coiling, but surgeons should be careful for injury of the branching vessels like the lateral lenticulostriate artery and they must be prepared for various inevitable situations that occur during surgery.ope