Internal carotid artery bifurcation aneurysms: Microsurgical strategies and operative nuances for different aneurysmal directions

BACKGROUND: Internal carotid artery bifurcation aneurysms (ICAbifAs), comprising approximately 5% of intracranial aneurysms, are characterized clinically by their tendency to occur at a younger age and surgically by the technical difficulties posed by their domes being adherent to the frontal lobe, their location at the apex of the sylvian fissure, and their relation to myriad perforator complexes. OBJECTIVE: To review the nuances of technique and operative strategy specific to aneurysmal direction in the light of our experience with ICAbifAs. METHODS: ICAbifAs managed at our institute from January 2001 to July 2016 were analyzed. Detailed analysis of clinical data, pre- and postoperative radiology, operative notes and videos, and clinical outcome was done. RESULTS: Fifty-one patients with ICAbifAs were treated in the study period out of which 40 patients underwent microsurgical clipping. The median age was 48 yr (range 14-68 yr). Nearly 95% of the patients presented in a good clinical grade (World Federation of Neurological Surgeons grade 1 and 2). At 6-mo follow-up, 36 patients (90%) had good clinical outcome (Glasgow Outcome Scale 4 and 5). According to their direction, ICAbifAs were grouped as anteriorly directed (10 cases), superiorly directed (23 cases), and posteriorly directed (7 cases). Operative techniques and nuances utilized depend on aneurysmal direction and are presented here. CONCLUSION: An appropriate surgical strategy based on the direction of ICAbifAs as per the preoperative radiology, meticulous dissection of aneurysmal wall from adjacent perforators, and clip application with the aim of remodeling the ICA bifurcation are integral to achieving a good outcome.