A I-segment aneurysms: management protocol based on a new classification.

Abstract

Aneurysms of proximal (AI)-segment of anterior cerebral artery (ACA) constitute <1% of all intracranial aneurysms. Management dilemmas of A1-segment aneurysms were studied utilizing a new classification based upon their location on the longitudinal and circumferential axis of A1-segment. Tertiary care referral center. This is a retrospective analysis of 14 patients (0.98%; mean age: 38.02 ± 15.74 years) with AI-segment aneurysms. The data collected included clinical features, computed tomography (CT) scan and CT-angiography (CTA)/digital subtraction angiography (DSA) findings, modified Hunt and Hess (H and H) grade, surgical steps and difficulties encountered. The modified Hunt and Hess (H and H) grades in the 14 patients were: grade I in two, grade II in two, grade III in four, grade IV in five and grade V in 1. The mean ictus-admission duration was 5.07 ± 2.30 days (range: 1-10 days). Multiple aneurysms were two. Thirteen patients underwent clipping and one, wrapping. Bilateral lateral ventricle hemorrhage occurred in 8 (66%) patients and frontal intracerebral hematoma in 2 (16.66%) patients. In one patient, the aneurysm could only be detected following the third angiogram. AI-aneurysms were classified as proximal (n = 6), distal (n = 7), and mid-segment (n = 1); and, anterior (n = 2), posterior-inferior (n = 7) and posterior-superior (n = 5). Follow-up (range: 6 months-10 years, mean: 2.9 years) recovery (assessed using Modified Rankin's score or mRS) correlated with preoperative status. The preoperative H and H grade and follow-up mRS status were as follows: H and H I (n = 2): mRS 0 (asymptomatic, n = 2); H and H II (n = 2): mRS 1 (minor symptoms without disability, n = 2); H and H III (n = 4):mRS 1 (n = 2) and mRS 2 (slight disability but performing unassisted activities of daily living, n = 1); H and H IV (n = 5): mRS 3 (moderate disability, requiring help for daily living but unassisted walking, n = 2) and mRS 4 (moderately severe disability, requiring help for daily living and walking, n = 2). One patient each from H and H grade III, IV and V died (mRS 6) during treatment due to severe vasospasm, pneumonitis and septicemia. AI-segment aneurysms have unique properties: rupturing of small-sized aneurysms; multiplicity; undetectable on initial imaging; frontal lobar/intraventricular bleeding; origin from main trunk and not bifurcating points; neck obscuration by AI-trunk; close proximity to perforators; and, associated AI-segment and ACA anomalies. A new classification identifies surgical difficulties inherent in different sites of origin of A1-aneurysms.