Hearing preservation in the removal of intracanalicular acoustic neuromas via the retrosigmoid approach.

In a series of 514 consecutive operations for complete excision of acoustic neuromas, 94 procedures were performed via a retrosigmoid approach to preserve the patient's hearing. Twenty-six of these procedures (5.1%) were performed in cases of intracanalicular tumor and 68 (13.2%) were for larger lesions in which most of the tumor was located medial to the porus acusticus within the cerebellopontine angle. Preservation of useful hearing was achieved in 13 (50%) of 26 patients with intracanalicular tumors and in 20 (29%) of 68 with larger tumors. A trend toward higher success rates in intracanalicular tumors appears to be present, although the difference is not statistically significant (p = 0.09). Normal or near normal facial function (House and Brackmann Grades I and II) was present postoperatively in 25 (96%) of 26 patients. Indications for treatment of intracanalicular acoustic neuromas are considered and treatment alternatives are reviewed. Results from other series reporting removal of intracanalicular acoustic neuromas are considered with respect to hearing conservation and postoperative facial nerve function. Surgical excision of intracanalicular acoustic neuromas in otherwise healthy patients appears to be warranted if preservation of useful binaural hearing is considered a worthwhile objective and if perioperative morbidity can be maintained at an acceptably low level. The retrosigmoid approach is familiar to all neurosurgeons and offers a comparable success rate for hearing conservation and probably a superior outcome in terms of facial nerve function when compared with the middle fossa approach.