Microsurgical Treatment of Meningiomas of the Cerebellopontine Angle with Internal Auditory Canal Extension

Introduction: Meningiomas represent the second most common tumor of the cerebellopontine angle (CPA). Tumors with internal auditory canal extension are rare. Materials and Methods: Retrospective analysis was conducted of 14 microsurgically treated meningiomas of the CPA with internal auditory canal extension during 1997–2007 (11 women, 3 men; age range, 27–66 years; 1 NF2 associated, 13 sporadic cases). All treated tumors were large and compressing the cerebellum and brainstem. One tumor extended through the jugular foramen to the parapharyngeal space. The most common symptoms were hearing loss (100%), tinnitus (87%), instability (73%), and trigeminal dysfunction (33%). Pathological BAEP was observed in 100%, and diagnosis of meningioma was expected on the preoperative MRI in all cases. Results: The retrosigmoid approach was applied in 13 patients, and in 1 case we used a combination of the retrolabyrinthine and infratemporal approaches. Meatotomy was performed in all of the cases. Radical removal (Simpson grades 1 and 2) was achieved in 86% and subtotal resection (Simpson grade 4) in 14%. One of these patients has undergone adjuvant external irradiation. Transient postoperative CN VII dysfunction (HB III) was observed in 14%; others had normal function. Preservation of preoperatively useful hearing was achieved in 83% of cases. In 21% of preoperatively nonuseful hearing ears, hearing improved to useful level. Improvement of preoperative CN V dysfunction was achieved in all cases. Transitory dysfunction of CNs V, IX, and X were present in 14% of cases. In the follow-up period (range 1–9 years; mean, 5.14 years), the only recurrence observed was in 1 patient with subtotal resection, which was further treated with LGN. Conclusion: Cerebellopontine angle meningiomas with internal auditory canal extension are rare. Radical microsurgical removal with anatomical and functional preservation of cranial nerves is possible in a majority of cases. Compared with vestibular schwannomas, hearing improvement after surgery can be expected in a more significant number of patients with meningiomas of the CPA.