Far Posterior Subtemporal Approach to the Dorsolateral Brainstem and Tentorial Ring: Technique and Clinical Experience

OBJECTIVE: Surgical access to the posterolateral mesencephalon or tentorial ring can be problematic, depending on the angle of the tentorium and associated venous structures. A far posterior subtemporal approach was developed that uses the wide opening of the tentorium and the option of supratentorial retraction of the cerebellum to provide an excellent angle of approach to this region. Details of this technique and a series of eight patients with lesions treated by this approach are presented. METHODS: Seven cavernous malformations and one dural arteriovenous malformation were approached in eight patients. In this far posterior subtemporal approach, a horseshoe incision is centered slightly behind the ear, with the caudal extent of the craniotomy defined by the temporal fossa floor. The entry of the vein of Labbé into transverse sinus is identified intradurally. If the vein enters anteriorly in the exposure, it is mobilized. Retractors are then placed, and the tentorium is visualized and opened laterally, avoiding the trochlear nerve. A thin, tapered retractor can be used to retract the cerebellum posterolaterally away from the brainstem. RESULTS: This approach was used to treat eight patients, and their lesions were successfully resected. Seven patients experienced good outcomes, and one patient, who presented with Hunt-Hess Grade IV subarachnoid hemorrhage from a dural arteriovenous malformation, experienced a fair outcome. CONCLUSION: The far posterior subtemporal approach is effective for approaching carefully selected lesions of the posterolateral mesencephalon and tentorial ring.