The Extended Retrosigmoid Approach:An Alternative To Radical Cranial Base Approaches For Posterior Fossa Lesions

Objective: The extended retrosigmoid approach is presented as a simple and safe modification of the traditional retrosigmoid approach, with increased exposure resulting from a limited mastoidectomy and skeletonization of the sigmoid sinus. Methods: Patients with posterior fossa vascular lesions treated with the extended retrosigmoid approach between 1997 and 2003 were reviewed. A detailed description of the surgical approach, as well as case illustrations, is provided. We present a video narrated by the senior author in which a description of the technique is offered. Results: Thirty-eight patients underwent this approach to manage 40 lesions, including 15 dural arteriovenous fistulae, 9 arteriovenous malformations, 10 cavernous malformations, and 6 aneurysms. The extended retrosigmoid approach differs from the traditional approach with its C-shaped skin incision, posterior mastoidectomy, and extensive dissection of the sigmoid sinus, craniotomy rather than craniectomy, and anterior mobilization of the sinus with the dural flap. Conclusion: The application of the extended retrosigmoid approach to a series of complex lesions in the posterior fossa demonstrates its applicability as an alternative to radical cranial base approaches. The extended retrosigmoid approach requires a fundamental change in the management of the sigmoid sinus. The neurosurgeon must be familiar with petrous bone anatomy, experienced dissecting through bone using a high-speed drill, and comfortable working directly over a major venous sinus. The technical modifications of the extended retrosigmoid approach can be incorporated into the neurosurgical repertoire and will enhance exposure of the cerebellopontine angle and deep vascular structures, thereby minimizing the need for brain retraction and other transpetrous approaches.