[What should be recommended to a patient with a small radiologically suspected acoustic neuroma?]

Criteria for therapeutic decision-making for intrameatal acoustic neurinomas that are suspected radiologically.

Retrospective evaluation.

114 surgically treated patients of the ORL Dept. of the University Erlangen-Nuremberg.

Rate of complications. Preservation of facial nerve function and hearing. Preoperative time course of hearing. Reliability of radiological examination. Progression of symptoms and tumor growth.

Surgical exposure and complete removal by the enlarged middle cranial fossa approach.

In 47% of cases surgery confirmed a neurinoma limited to the internal auditory meatus. In 41%, tumors were larger than expected and had protruded into the cerebellopontine angle, indicating preoperative tumor growth during an average period of 5.4 months before surgery could be completed. The remaining 12% of patients were found to have a facial neurinoma, meningioma or non-tumorous lesion of the internal auditory canal. No permanent neurological deficits or fatalities occurred in any of the patients treated. Facial function was favorable in 88% and moderate pareses or synkineses occurred in 12%. The degree of hearing preservation depended on the preoperative situation. When the preoperative pure-tone average (at 0.5, 1, 2 and 4 kHz) was 30 dB or less, hearing levels of less than 90 dB could be preserved in 70% of cases. Findings also demonstrated that the complication rate and success of function preservation were similar to younger patients in patients older than 60 years (n = 21). Without surgery auditory acuity decreased by 10 dB per year. The volume of intrameatal neurinomas in 7/10 cases followed by MRI doubled during a median following time of 32 months.

Acoustic neurinoma surgery by the enlarged middle cranial fossa approach is a safe procedure with low complication rates. The percentages of preservation of facial function and hearing can be excellent in cases with small tumors and good preoperative hearing. To date no parameter has been found to predict tumor growth or the time course for hearing loss in individual cases. Surgical ablation of radiologically suspected, small acoustic neurinoma by the transtemporal approach is recommended.