Combined transmastoid approach variations for resecting giant cystic vestibular schwannomas

Abstract

Surgical removal of giant (over 40 mm) vestibular schwannomas (VSs) is associated with higher rates of postoperative complications than smaller tumors. Especially, the cystic VSs carry different risks of postoperative complications when compared to solid VSs. The transmastoid approaches, including the retro‒ and translabyrinthine approaches have several advantages in that these approaches are less likely to cause damage to the cranial nerves, cerebellum, and brainstem during surgery. They provide not only a straight corridor to the cerebellopontine angle (CP angle) , but also the shortest access to the internal auditory canal and jugular foramen. However, the operative field is deep and narrow, and the operative view is unfamiliar compared to that in the lateral suboccipital approach (retrosigmoid approach) . We have used combined transmastoid approaches that provide multidirectional operative corridors to the CP angle enables the surgeon to safely perform radical resection of giant cystic VSs. These surgical approaches can be divided into several variations. Each variation consists of a transmastoid approach (retro‒ or translabyrinthine approach) and additional subtemporal or suboccipital craniotomies with or without tentorial incision. Thus, transmastoid approaches can be combined with other procedures to enhance the exposure and resectability of giant cystic VSs. These combined transmastoid approaches provide successful resection of the lesion with low morbidity and minimum brain retraction.