ORIGINAL RESEARCH Facial Nerve Outcomes in Middle Cranial Fossa vs Translabyrinthine Approaches Brandon Isaacson, MD, Steven A. Telian, MD, and Hussam K. El-Kashlan, MD, Ann Arbor, Michigan OBJECTIVE: To compare the final facial nerve outcomes be- tween middle cranial fossa (MCF) vs translabyrinthine (TL) re- section of size-matched vestibular schwannomas. STUDY DESIGN AND SETTING: Retrospective case review at a tertiary care hospital. All patients who underwent resection utilizing either MCF or TL approaches with tumors 18 mm or smaller and complete data were included in the analysis. One hundred twenty-four patients were identified meeting the above criteria, with sixty-three in the translabyrinthine group and sixty- one in the middle fossa group. One-week-postoperative and final facial nerve examinations were compared in the two surgical groups. Patients were separately analyzed in subgroups: tumors smaller than 10 mm and those that were between 10 and 18 mm. RESULTS: The tumor size range for the MCF group was 3-18 mm while it was 4-18 mm for the TL group. No statistically significant difference was found in facial nerve outcomes between the two surgical groups, at the first postoperative visit week and at last follow-up. CONCLUSION: Facial nerve outcomes are similar using TL and MCF approaches for resection of vestibular schwannomas up to 18 mm in size. SIGNIFICANCE: Patients undergoing the MCF approach for hearing preservation can be counseled that there is no increased risk of permanent facial nerve weakness, compared to the TL approach. EBM RATING: B-3 © 2005 American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. All rights reserved. T he middle cranial fossa approach was first described in 1904 as a means for sectioning the vestibular nerve. William House reintroduced this approach in 1961 to de- compress the internal auditory canal in cases of extensive otosclerosis. 1 This approach was initially utilized for exci- sion of vestibular schwannomas of all sizes. Eventually it was realized that it was particularly effective in smaller tumors when hearing preservation was desired. This ap- proach made hearing preservation a possibility, especially in cases where tumor extended into the lateral one-third of the internal auditory canal. Since the introduction of the operating microscope, the mortality and morbidity rates in surgical excision of vestibular schwannomas have drasti- cally declined. The rate of anatomic preservation of the facial nerve exceeds 95% in a vast majority of studies; however, the functional preservation is still around 90%. 2 Tumor size, age of the patient, and surgical approach have all been implicated as prognostic factors in facial function. Until recently, it was generally thought that facial nerve outcomes are poorer in middle cranial fossa (MCF) ap- proach when compared to translabyrinthine (TL) approach. This was attributed to the impression that the facial nerve undergoes greater manipulation in middle fossa approach, since the facial nerve overlies the tumor and must be mo- bilized to permit access to the vestibular schwannoma. Sev- eral studies have compared approaches in regard to both facial nerve function and hearing preservation. 3-5 In general, these studies showed no significant difference in facial nerve outcomes between the two approaches except in tu- mors with greater than 10 mm cerebellopontine angle (CPA) extension. These studies, however, did not size- match tumors between the two surgical approaches but rather included all tumors smaller than a certain size cutoff point. The present study was undertaken to compare facial nerve outcomes in patients undergoing the translabyrinthine From the University of Michigan Hospitals, Department of Otolaryn- gology–Head and Neck Surgery. Presented at the Annual Meeting of the American Academy of Otolar- yngology–Head and Neck Surgery, New York, NY, September 19-22, 2004. Reprint requests: Hussam K. El-Kashlan, MD, Department of Otolar- yngology–Head and Neck Surgery, 1500 E. Medical Center Dr, TC 1904, Ann Arbor, MI 48109-0312. E-mail address: hussam@umich.edu. Otolaryngology–Head and Neck Surgery (2005) 133, 906-910 0194-5998/$30.00 © 2005 American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. All rights reserved. doi:10.1016/j.otohns.2005.08.021