Retrosigmoid versus middle fossa surgery for small vestibular schwannomas

The objective was to determine the effect of approach, middle fossa versus retrosigmoid, on the hearing and facial nerve outcome of surgery for small vestibular schwannomas.

The study had two parts, a case study of patient data entered into a prospectively designed database at the author's institution, and a meta-analysis of similar published data.

There were 73 of the author's private practice patients who met the inclusion criteria of intracanalicular vestibular schwannoma and total tumor removal by a retrosigmoid approach. American Academy of Otolaryngology-Head and Neck Surgery standardized hearing and facial nerve classifications of these patients and similar data from 11 other institutions were used to compare results of the two surgical approaches.

Median facial nerve results for all institutions were significantly better with the retrosigmoid approach (grade I: 95% for retrosigmoid and 81% for middle fossa). Median hearing results trended toward better outcome with the middle fossa approach (same preoperative hearing class: 48% for middle fossa and 39% for retrosigmoid). Individual institution had an equal or greater effect on outcome than the choice of surgical approach.

Surgical team accounted for more variability in hearing and facial nerve outcome than did approach. Retrosigmoid approach yielded significantly better facial nerve outcome. The trend toward better hearing outcome with the middle fossa approach may never achieve statistical significance across institutions because of high variability among surgical teams and small numbers of teams reporting results.