Surgical Management of Meningiomas Involving or Originating from the Internal Auditory Canal

Objective: Meningiomas account for approximately 15% of brain tumors and are the most common tumors of the petroclival region and the second most common tumors of the cerebellopontine angle. Involvement of the internal auditory canal (IAC) by the tumor compromises the facial and vestibulocochlear nerves, as well as the postoperative prognosis of facial function and hearing. In this study, we report 19 cases of posterior fossa meningiomas involving the IAC and 1 case of a meningioma originating from the IAC. The outcomes of these patients are presented. Methods: Twenty cases of meningiomas involving the IAC were surgically treated at our institution between 1987 and 2008. There were 15 petroclival meningiomas, 4 cerebellopontine angle (CPA) meningiomas, and 1 intracanalicular meningioma. These patients are part of a larger series of 610 CPA lesions operated on during this period (82 petroclival meningiomas and 528 other lesions). The suboccipital lateral craniotomy with intraoperative cochlear and facial nerve monitoring and image-guided navigation was the approach of choice. The IAC was drilled widely to expose the tumor and the cranial nerves. Results: Radical tumor removal (Simpson grade1) was possible in 13 cases. Simpson grade 2 was achieved in 4 patients, and 3 patients achieved grade 3. Total tumor removal from the IAC was possible in all cases. The preservation rate of hearing and facial nerve function was higher following resection of CPA meningiomas than in petroclival meningiomas. Conclusions: Degree of involvement of the IAC was an important factor in functional preservation of facial nerve and hearing.