TECHNICAL ASPECTS AND RECENT TRENDS IN THE MANAGEMENT OF LARGE AND GIANT MIDBASILAR ARTERY ANEURYSMS

OBJECTIVE: Cranial base approaches that involve radical petrosectomy a re associated with significant rates of morbidity. We have sought alte rnative approaches to the midbasilar artery to reduce the extent of te mporal bone removal and correspondingly to reduce complications while still providing adequate surgical exposure. The extended orbitozygomat ic and far-lateral approaches are two such approaches. We compared our experience with these approaches to our experience with the standard transpetrosal approaches in the treatment of midbasilar artery aneurys ms. METHODS: Between 1990 and 1995, 28 patients with large and giant m idbasilar artery aneurysms were treated with approaches involving eith er radical or conservative petrosectomy. RESULTS: Overall, good outcom es (Glasgow Outcome Scale scores of 1 and 2) were observed in 21 patie nts (75%), and three patients (11%) had permanent treatment-associated neurological deficits. Four patients died. Later in the series, the p terional-subtemporal approach (four patients) was supplanted by the or bitozygomatic approach (six patients). The increased use of hypothermi c circulatory arrest improved exposure of the midbasilar region from a bove (orbitozygomatic approach) and below (far-lateral approach, 13 pa tients). Concomitantly, the use of transpetrosal approaches (five pati ents) decreased. CONCLUSION: Modified orbitozygomatic and far-lateral approaches adequately expose the midbasilar region and can replace tra nspetrosal approaches in some cases. These extended approaches can be associated with lower morbidity rates than can transpetrosal approache s. Hypothermic circulatory arrest is critical to clipping large and gi ant midbasilar artery aneurysms directly when approaches that conserve the temporal bone are used.