Hearing preservation surgery for vestibular schwannomas via the retrosigmoid transmeatal approach: surgical tips.

Maximum tumor extirpation with preservation of the facial and cochlear nerve function is the goal of surgery for vestibular schwannoma. To preserve cochlear nerve function, the surgeon must employ a detailed knowledge of microanatomy, precise microsurgical techniques, and persistence. This paper describes the "pearls" of surgical techniques based on the anatomical study inside the mastoid from the view of the retrosigmoid transmeatal approach. A total of 592 consecutive patients underwent surgical removal of unilateral vestibular schwannoma (VS) between January 1994 and December 2009. The hearing preservation rate was 53.7 % for large vestibular schwannomas (>20 mm in diameter) and 74.1 % for tumors of all sizes. The key procedures for hearing preservation surgery are as follows: bloodless microdissection, sufficient coring-debulking, capsular elevation to locate the facial and cochlear nerves both electrophysiologically and by visual observation, sharp dissection of the facial and cochlear nerves, and avoidance of heat and mechanical injury to the nerves, the internal auditory artery, and the brain stem. Besides these techniques, appropriate instruments are essential to preserve hearing. The function of the facial and cochlear nerves should be the foremost concern. Meticulous techniques and the knowledge of microsurgical anatomy lead to hearing preservation with maximum tumor removal.