Technical aspects and recent trends in the management of large and giant midbasilar artery aneurysms

Cranial base approaches that involve radical petrosectomy are associated with significant rates of morbidity. We have sought alternative approaches to the midbasilar artery to reduce the extent of temporal bone removal and correspondingly to reduce complications while still providing adequate surgical exposure. The extended orbitozygomatic 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 aneurysms.

Between 1990 and 1995, 28 patients with large and giant midbasilar artery aneurysms were treated with approaches involving either radical or conservative petrosectomy.

Overall, good outcomes (Glasgow Outcome Scale scores of 1 and 2) were observed in 21 patients (75%), and three patients (11%) had permanent treatment-associated neurological deficits. Four patients died. Later in the series, the pterional-subtemporal approach (four patients) was supplanted by the orbitozygomatic approach (six patients). The increased use of hypothermic circulatory arrest involved exposure of the midbasilar region from above (orbitozygomatic approach) and below (far-lateral approach, 13 patients). Concomitantly, the use of transpetrosal approaches (five patients) decreased.

Modified orbitozygomatic and far-lateral approaches adequately expose the midbasilar region and can replace transpetrosal approaches in some cases. These extended approaches can be associated with lower morbidity rates than can transpetrosal approaches. Hypothermic circulatory arrest is critical to clipping large and giant midbasilar artery aneurysms directly when approaches that conserve the temporal bone are used.