2018 年 46 巻 2 号 p. 111-116
The risk of complications is reportedly high after surgical clipping of aneurysms (ANs) in the middle cerebral artery (MCA-AN), on the medial side of the limen insulae. These are classified as M1 segment aneurysms or short M1 aneurysms. We named these aneurysms medial insulae MCA-ANs and classified them into four types as follows: 1) lenticulostriate artery (LSA) M1 ANs, 2) cortical M1 ANs, 3) short M1 ANs, and 4) anterior temporal artery (ATA) M1 ANs. Subsequently, we analyzed the surgical outcomes for each type. We had 21 cases of medial insulae MCA-ANs (including 5 ruptured cases) treated with surgical clipping and monitoring using motor-evoked potential (MEP) and indocyanine green video-angiography (ICG-VAG). Of the patients, 8 were men and 13 were women. Their mean age was 66 years (range, 35-83 years). The mean aneurysm size was 5.5 ± 2.2 mm. Of the cases, 3 (14.3%) were LSA M1 ANs; 6 (28.6%), cortical M1 ANs; 10 (47.6%), short M1 ANs; and 2 (9.5%), ATA M1 ANs. Two patients had surgical ischemic complications from the perforating arteries. One had a case of short M1 AN with an asymptomatic left striatum infarction, while the other had a case of cortical M1 AN with postoperative transient paralysis, although the intraoperative MEP decreased. No permanent neurological deficit remained. Medial insulae MCA-ANs are considered hemiparetic complications. Thus, surgeons must accurately judge the type of aneurysm and understand the relationship between the neck and the perforators before clipping.