Midline approaches to cerebrovascular lesions

Abstract

Midline posterior circulation aneurysms lie in one of the most difficult regions to access surgically. The standard lateral and transtentorial approaches are useful, yet at times are hindered by suboptimal visualization, a long working distance, and possible need for retraction of the brain stem and lower cranial nerves. The anterior midline transclival approach is the most direct route to these aneurysms and offers optimal exposure such that proximal and distal vascular control is possible if necessary. The clivus can be reached by a transoral, transnasal, or transcervical route. The major drawback of the anterior midline transclival approach is the high incidence of complications, particularly the high incidence of cerebrospinal fluid leak and meningitis. A review of the 35 reported cases in the literature since 1966 showed 71% excellent outcomes and 24% mortality. There was a 51% incidence of cerebrospinal fluid leak and 43% meningitis (3 of the 15 cases of meningitis were fatal). There were 19 (54%) other complications, 4 (11%) of which caused deaths, 3 (9%) of which caused major permanent deficits, and 5 (14%) of which caused minor deficits. New techniques have been developed for prevention of cerebrospinal fluid leaks, and modern broad-spectrum antibiotics lessen the chance of permanent neurological sequelae from meningitis. As the complication rate improves, the anterior midline transclival approach may become even more attractive for the treatment of difficult midline posterior circulation aneurysms.