PREDICTIVE FACTORS INFLUENCING HEARING PRESERVATION AFTER REMOVAL OF ACOUSTIC TUMORS USING MIDDLE FOSSA APPROACH

Jeong-Hoon Oh, Woo-Jin Kim, Ki-Hong Chang

Department of Otolaryngology-Head and Neck Surgery, The Catholic University of Korea, Seoul, Korea

Introduction

With the advent of sophisticated microsurgical and anesthetic techniques, morbidity and mortality have dramatically decreased in vestibular schwannoma (VS) surgery.1 Advances in imaging techniques and audio-vestibular testing, which allowed earlier diagnosis, have led most surgeons to attempt two additional goals: conservation of facial function and hearing preservation after complete removal of the tumor.2,10,11 In these days, the post-operative hearing preservation is becoming a critical issue as tumors are smaller when found.3,11 Achievement of this depends on patient factors, tumor factors, as well as the surgical technique (translabyrin-thine, middle-fossa, and retro-sigmoid approach).4,7,11 Advantages of the middle-fossa approach compared to the retro-sigmoid approach include the higher rates of hearing preservation, nearly complete exposure of the IAC, and the higher possibility of surgery even if the tumor is involved to the lateral IAC.5,8 These advantages have made the middle-fossa approach an otolaryngologist-friendly technique.

The aim of this study was to analyze predictive factors that influence post-operative hearing level after removal of VS using middle fossa approach, and to re-evaluate the previous limitations inherent in this approach.

Material and methods

The study participants are 16 patients who received the surgery for removal of acoustic tumor using middle-fossa approach from January 1st 2002 to January 1st 2012. Two groups were hearing preserved group (50 dB and above, n = 8) and unpreserved group (less than 50 dB, n = 8) according to the post-operative hearing level. They were compared retrospectively by means of predictive factors, including the size of the tumor, the presence of extension to cerebellopontine angle (CPA) and the lateral fundus, the presence of tumor adhesion to the facial nerve, the type of nerve originating the tumor, the course of facial nerve, degree of post-operative facial-nerve palsy and the pre-operative hearing level.

Results

The size of the tumor, the presence of extension to CPA and lateral fundus, degree of adhesion between the tumor and facial nerve, the course of facial nerve, and the degree of post-operative facial nerve palsy were not significantly different between the two groups (p > 0.05) (Figs. 1 and 2). There was no significant correlation of the length of extension to CPA between two groups either (Fig. 2). Tumors arose most commonly from the superior vestibular nerve, in 56% of patients, followed by the inferior vestibular nerve in 44%.

image

Fig. 1. Comparison of the size of tumor (A) and the presence of extension to cerebellopontine angle (CPA) (B) and lateral fundus (C) between two groups (p > 0.05).

image

Fig. 2. Comparison of the length of extension to CPA (A) and the degree of adhesion between the tumor and facial nerve (B) between two groups.

Discussion and conclusion

In previous studies, factors that influence the post-operative hearing level after the middle-fossa approach have been pre-operative hearing level and the degree of tumor extension to CPA or IAC lateral fundus.1,6,11 Better pre-operative hearing level means there is less adhesion between the tumor and the auditory nerve. Likewise, less extension to the fundus means better surgical field exposure.9 The extension of the tumor to the lateral fundus was known to be a contra-indication of surgical excision because of the high risk of hearing loss. However, our study indicates that there was no significant correlation between the presence of extension to lateral fundus and the possibility of hearing loss after the surgery. This suggests that the middle-fossa approach may be considered even with the presence of tumor extension to lateral fundus. More cases and standardized operation-procedure-based analysis is needed for a more generalized result to confirm this suggestion.

References

1Brackmann DE, et al. Prognostic factors for hearing preservation in vestibular schwannoma surgery. Am J Otol 21:417–424, 2000

2Darwish BS, Bird PA, Goodisson DW, Bonkowski JA, MacFarlane MR. Facial nerve function and hearing preservation after retrosigmoid excision of vestibular schwannoma: christchurch hospital experience with 97 patients. ANZ J Surg 75:893–896, 2005

3DeMonte F, Gidley PW. Hearing preservation surgery for vestibular schwannoma: experience with the middle fossa approach. Neurosurg Focus 33(3):E10, 2012

4Hecht CS, Honrubia VF, Wiet RJ, Sims HS. Hearing preservation after acoustic neuroma resection with tumor size used as a clinical prognosticator. Laryngoscope 107:1122–1126, 1997

5Irving RM, Jackler RK, Pitts LH. Hearing preservation in patients undergoing vestibular schwannoma surgery: comparison of middle fossa and retrosigmoid approaches. J Neurosurg 88:840–845, 1998

6Jacob A, Robinson LL, Bortman JS Jr, Yu L, Dodson EE, Welling DB. Nerve of origin, tumor size, hearing preservation, and facial nerve outcomes in 359 vestibular schwannoma resections at a tertiary care academic center. Laryngoscope 117:2087–2092, 2007

7Kutz JW, et al. Hearing preservation using the middle fossa approach for the treatment of vestibular schwannoma. Neurosurgery 70:334–340, 2012

8Mangham CA Jr. Retrosigmoid versus middle fossa surgery for small vestibular schwannomas. Laryngoscope 114:1455–1461, 2004

9Mohr G, Sade B, Dufour JJ, Rappaport JM. Preservation of hearing in patients undergoing microsurgery for vestibular schwannoma: degree of meatal filling. J Neurosurg 102:1–5, 2005

10Rabelo de Freitas M, Russo A, Sequino G, Piccirillo E, Sanna M. Analysis of hearing preservation and facial nerve function for patients undergoing vestibular schwannoma surgery: the middle cranial fossa approach versus the retrosigmoid approach – personal experience and literature review. Audiol Neurootol 17:71–81, 2012

11Staecker H, Nadol JB, Ojeman Jr R, Ronner S, McKenna MJ. Hearing preservation in acoustic neuroma surgery: middle fossa versus retrosigmoid approach. Am J Otol 21:399–404, 2000

Address for correspondence: Ki-Hong Chang, khchang@catholic.ac.kr

Cholesteatoma and Ear Surgery – An Update, pp. 337–339

Edited by Haruo Takahashi

2013 © Kugler Publications, Amsterdam, The Netherlands