Patterns of Hearing Loss Following Retrosigmoid Excision of Unilateral Vestibular Schwannoma

Abstract

Objectives To determine the pattern of auditory responses, time-course of hearing deterioration, and possible site of lesion following retrosigmoid excision of unilateral vestibular schwannomas.

Design Prospective, nonrandomized, observational pilot study.

Setting Tertiary referral medical center.

Main outcome measures Preoperative and postoperative pure-tone and speech audiometry, auditory brainstem response testing, and distortion product otoacoustic emissions were performed in 20 patients. Testing was conducted every 24 hours for the duration of hospitalization. Transtympanic electrocochleography was performed if delayed deterioration of auditory responses was documented.

Results Of the 20 patients, 7 had no discernible cochlear nerve at the end of the procedure. Of the 13 patients with an intact nerve, 6 retained hearing, 3 with evidence of reduced neural function. Of the 7 who lost hearing despite an intact nerve, 5 lost at least cochlear and possibly also neural function, and 1 had reduced neural function but retained cochlear function. There were two examples of delayed deterioration of cochlear nerve responses.

Conclusions Hearing loss following retrosigmoid removal of vestibular schwannomas most often involves loss of at least cochlear function, possibly in addition to neural damage. In a smaller number of cases anacusis or hearing deterioration can be attributed to purely neural trauma.

Keywords

acoustic neuroma - vestibular schwannoma - hearing preservation

• References

• 1 Colletti V, Fiorino FG, Carner M, Tonoli G. Mechanisms of auditory impairment during acoustic neuroma surgery. Otolaryngol Head Neck Surg 1997; 117 (6) 596-605
• 2 Kim AH, Edwards BM, Telian SA, Kileny PR, Arts HA. Transient evoked otoacoustic emissions pattern as a prognostic indicator for hearing preservation in acoustic neuroma surgery. Otol Neurotol 2006; 27 (3) 372-379
• 3 Morlet T, Dubreuil C, Duclaux R, Ferber-Viart C. Preoperative speech and pure-tone audiometry in four types of patients with acoustic neuroma. Am J Otolaryngol 2003; 24 (5) 297-305
• 4 Levine RA, Ojemann RG, Montgomery WW, McGaffigan PM. Monitoring auditory evoked potentials during acoustic neuroma surgery. Insights into the mechanism of the hearing loss. Ann Otol Rhinol Laryngol 1984; 93 (2 Pt 1) 116-123
• 5 Sekiya T, Iwabuchi T, Kamata S, Ishida T. Deterioration of auditory evoked potentials during cerebellopontine angle manipulations. An interpretation based on an experimental model in dogs. J Neurosurg 1985; 63 (4) 598-607
• 6 Sekiya T, Møller AR. Cochlear nerve injuries caused by cerebellopontine angle manipulations. An electrophysiological and morphological study in dogs. J Neurosurg 1987; 67 (2) 244-249
• 7 Friedman RA, Brackmann DE, Mills D. Auditory-nerve integrity after middle-fossa acoustic-tumor removal. Otolaryngol Head Neck Surg 1998; 119 (6) 588-592
• 8 Perlman HB, Kimura R, Fernandez C. Experiments on temporary obstruction of the internal auditory artery. Laryngoscope 1959; 69 (6) 591-613
• 9 Committee on Hearing and Equilibrium. American Academy of Otolaryngology – Head and Neck Surgery. Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma (vestibular schwannoma). Otolaryngol Head Neck Surg 1995; 113 (3) 179-180
• 10 Gardner G, Robertson JH. Hearing preservation in unilateral acoustic neuroma surgery. Ann Otol Rhinol Laryngol 1988; 97 (1) 55-66
• 11 Brackmann DE, Owens RM, Friedman RA , et al. Prognostic factors for hearing preservation in vestibular schwannoma surgery. Am J Otol 2000; 21 (3) 417-424
• 12 Dornhoffer JL, Helms J, Hoehmann DH. Hearing preservation in acoustic tumor surgery: results and prognostic factors. Laryngoscope 1995; 105 (2) 184-187
• 13 Robinette MS, Bauch CD, Olsen WO, Harner SG, Beatty CW. Nonsurgical factors predictive of postoperative hearing for patients with vestibular schwannoma. Am J Otol 1997; 18 (6) 738-745
• 14 Josey AF, Glasscock III ME, Jackson CG. Preservation of hearing in acoustic tumor surgery: audiologic indicators. Ann Otol Rhinol Laryngol 1988; 97 (6 Pt 1) 626-630
• 15 Shimamura N, Sekiya T, Yagihashi A, Suzuki S. Temporal pattern of cochlear nerve degeneration following compression injury: a quantitative experimental observation. J Neurosurg 2002; 97 (4) 929-934
• 16 Cacace AT, Parnes SM, Lovely TJ, Kalathia A. The disconnected ear: phenomenological effects of a large acoustic tumor. Ear Hear 1994; 15 (4) 287-298
• 17 Hatayama T, Sekiya T, Suzuki S, Iwabuchi T. Effect of compression on the cochlear nerve: a short- and long-term electrophysiological and histological study. Neurol Res 1999; 21 (6) 599-610
• 18 Sekiya T, Møller AR, Jannetta PJ. Pathophysiological mechanisms of intraoperative and postoperative hearing deficits in cerebellopontine angle surgery: an experimental study. Acta Neurochir (Wien) 1986; 81 (3-4) 142-151
• 19 Sekiya T, Yagihashi A, Asano K, Suzuki S. Nimodipine ameliorates trauma-induced cochlear neuronal death. Neurol Res 2002; 24 (8) 775-780
• 20 Strauss C, Bischoff B, Neu M, Berg M, Fahlbusch R, Romstöck J. Vasoactive treatment for hearing preservation in acoustic neuroma surgery. J Neurosurg 2001; 95 (5) 771-777
• 21 Colletti V, Fiorino FG, Mocella S, Policante Z. ECochG, CNAP and ABR monitoring during vestibular Schwannoma surgery. Audiology 1998; 37 (1) 27-37
• 22 Sabin HI, Prasher DK, Bentivoglio P, Symon L. Preservation of cochlear potentials in a deaf patient fifteen months after excision of an acoustic neuroma. Scand Audiol 1987; 16 (2) 109-111
• 23 Galambos R. The BER in the ICU. In: Naunton RF, Fernandex C, , eds. Evoked Electrical Activity in the Auditory System. New York: Academic Press; 1978: 405-408
• 24 Hashimoto I, Ishiyama Y, Yoshimoto T, Nemoto S. Brain-stem auditory-evoked potentials recorded directly from human brain-stem and thalamus. Brain 1981; 104 (Pt 4) 841-859