Selection Strategy for Optimal Keyhole Approaches for Middle Cerebral Artery Aneurysms: Lateral Supraorbital Versus Minipterional Craniotomy

BACKGROUND/OBJECTIVE: The lateral supraorbital (LS) and minipterional (MP) approaches have been reported for treating intracranial aneurysms as alternative to the pterional approach. We describe our decision making for selecting the minicraniotomy, LS versus MP, for managing noncomplex aneurysms of the middle cerebral artery (MCA), based on the depth of the aneurysm within the Sylvian fissure. METHODS: We report on a consecutive case series of 50 patients who underwent clipping of 54 ruptured/unruptured MCA aneurysms by means of LS or MP craniotomies. The distance between the MCA (M1) origin and the aneurysmal neck is key to selection of the approach: LS was used for MCA aneurysms < 15 mm from the M1 origin and MP for MCA aneurysms >= 15 mm from the M1 origin. RESULTS: 11 of 50 patients presented with subarachnoid hemorrhage (10 ruptured MCA aneurysms). Overall, 59 aneurysms were successfully clipped (54 of the MCA). The mean distance between the M1 origin and the aneurysmal neck was 10.1 mm (range, 4-17 mm) for patients treated by LS and 20 mm (range, 15-30 mm) for those treated by MP. All but 1 MCA aneurysms were successfully treated. At last follow-up (mean, 14 months), no reperfusion of the clipped aneurysms was observed. CONCLUSION: Our strategy for selecting the keyhole approach based on the depth of the aneurysm within the Sylvian fissure is efficient and safe. We suggest the use of the LS approach when the aneurysm is < 15 mm from the M1 origin and the MP approach when the aneurysm is >= 15 mm from the M1 origin.