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Retrosigmoid approach to cerebellopontine angle tumor resection: Surgical modifications

INTRODUCTION The cerebellopontine angle (CPA) is a complex triangular space bounded by the brainstem medially, the cerebellum superiorly and posteriorly, and the temporal bone laterally. Tumors of the CPA account for 5% to 10% of all intracranial neoplasms, with the most frequent being vestibular schwannomas, followed by meningiomas and epidermoid tumors. Multiple surgical approaches are available for extirpation of these lesions. For tumors primarily located in the CPA with minimal lateral extension into the internal auditory canal (IAC), the retrosigmoid approach provides wide exposure and improved safety when dissecting the tumor from the brainstem and lower cranial nerves.1 The main pitfall of the standard retrosigmoid/suboccipital approach is the need for a larger, posterior craniotomy and cerebellar retraction to fully visualize the CPA. In the standard approach, a craniotomy is first performed immediately posterior to the sigmoid sinus and inferior to the transverse sinus. Cerebrospinal fluid (CSF) pressure is then decreased through decompression of the cistern. Retractors are then placed to retract the lateral cerebellum posteriorly.2 We present surgical modifications to the standard retrosigmoid approach that eliminate the need for cerebellar retraction for visualization of the CPA and utilized only native bone for reconstruction of the operative defect. Also, complication rates in association with this approach as compared to previously reported rates with the standard retrosigmoid/suboccipital approach will be presented.