Mirror Aneurysms Among Multiple Aneurysms: Lesser of the Two Evils

To highlight the management nuances in addressing mirror aneurysms (MirAns) in a subset of multiple aneurysms.

A retrospective study was carried out and all multiple intracranial aneurysms (n = 70) over 9 years were identified. Exclusion criteria were associated arteriovenous malformations, moyamoya disease, and either traumatic or mycotic aneurysms or those managed by endovascular approach alone. Patients were grouped as MirAn and nonmirror aneurysms (nMirAns). Outcome was assessed by Glasgow Outcome Score at 1 month. The Pearson χ(2) test or Fisher exact test were used to establish association.

MirAns (n = 17) accounted for 2.1% of all intracranial aneurysms and 24.3% of multiple aneurysms. Female predilection was eminent in the MirAn group (3.25:1) compared with the nMirAn group (2.5:1). The middle cerebral artery (n = 6) followed by the internal carotid artery-posterior communicating artery (n = 5) were the most common sites of the MirAns. There was no significant difference between the 2 groups for hypertension or age (MirAn, 52 years [± 11.231]; hypertension, 52.9%; nMirAn, 48.58 years [± 12.97]; hypertension, 54.7%). There was a definite trend towards less intraoperative rupture (MirAn, 4/17; nMirAn, 27/53; P = 0.048), decreased intraoperative vasospasm (MirAn, 1; nMirAn, 11) in the MirAn group. Development of infarct was significantly less in the MirAn group (P = 0.027) with a better outcome (13 in MirAn and 26 in nMirAn had good outcome; P = 0.048).

MirAns are not significantly associated with risk factors such as age, hypertension, and diabetes. Intraoperative rupture, vasospasm, and infarct are less common, with a tendency towards better neurologic outcome compared with nMirAns.