Contribution of drilling posterior wall of the internal auditory meatus in microsurgical treatment for vestibular schwannomas

doi:10.3969/j.issn.1671-2897.2009.01.008

Abstract：Objective To evaluate the effect of surgical treatment in vestibular schwannomas (VSs) with removal of the posterior meatal wall for intrameatal tumor. Methods A retrospective study was perfomed in 103 VSs patients who had undergone microsurgical removal. These patients were operated via retrosigmoid, transmeatal approach to establish a surgical approach that provides better access to the internal auditory meatus (IAM) in VSs removal. After posterior meatal wall was drilled, the anatomic location of the labyrinth with regard to the sigmoidfundus line (S-F line) and the extent of bone removal from the IAM were evaluated by pre and postoperative CT in all patients. Results Postoperative CT showed that the mean length of the posterior wall from the fundus was shortened to 4.6 mm±1.0 mm (n = 48) in the partially resected group; in 55 patients of the widely opened IAM group, the posterior wall remained a mean length of 1.9 mm±0.5 mm from the fundus. The location of the labyrinth in relation to the SF line was lateral type in 52 cases, line type in 23 cases, and medial type in 28 cases. In 101 patients, total tumor removal was achieved by visual inspection and postoperative MR imaging, with a complete resection rate of 98.1 %. Anatomic preservation of the facial nerve was achieved in 101 patients, and for 2 cases of nerve discontinuity, immediate endtoend facial nerve anastomosis was performed during the surgical procedures. The facial nerve was completely anatomically preserved in 18 cases with small tumors (100 %). There was no surgeryrelated permanent complication in this series of patients with the mortality rate of 0%. Conclusion The removal of the posterior meatal wall of IAM can provide a better surgical approach for VSs treatment which is helpful for complete tumor resection with reduction of morbidity and maintenance of normal neurological function.