Preservation of the auditory nerve function after translabyrinthine removal of vestibular schwannoma

Objective To evaluate the function of the postoperative auditory nerve preserved after translabyrinthine (TL) vestibular schwannoma (VS) removal. Methods Fifteen patients, who underwent unilateral VS resection via a TL approach, were preserved auditory nerve anatomically. The size and location of VS were measured on MRI preoperatively. After surgery, the electrical stimulation test (EST) or electrically evoked auditory brainstem response (EABR) was performed. Results Four cases (27%) out of fifteen patients were retained the functional integrity of the auditory nerve after surgery. The maximum tumor size in the group with a positive response to EST or EABR was significantly smaller than that in the group with a negative response to EST. It seems to be difficult to preserve auditory nerve function in cases where a tumor extends to the fundus of internal auditory canal. Conclusion These results suggest that size of tumor and/or extension of tumor to the fundus might be important factors in preserving the auditory nerve function even if using a TL approach.