The first experience with the use of direct monitoring of the auditory nerve in vestibular schwannoma surgery in the Czech Republic

Czech version

Authors: Z. Fík ¹; A. Vlasák ²; Z. Čada ¹; R. Schuler ³; J. Lazák ¹; V. Svobodová ¹; J. Vokřál ^1,4; E. Zvěřina ¹; J. Betka ¹
Authors‘ workplace: Klinika otorinolaryngologie a chirurgie hlavy a krku 1. LF UK a FN Motol, Praha ¹; Neurochirurgická klinika dětí a dospělých 2. LF UK a FN Motol, Praha ²; Research and Development, Dr. Langer Medical GmbH, Waldkirch, Německo ³; Foniatrická klinika 1. LF UK a VFN v Praze ⁴
Published in: Cesk Slov Neurol N 2021; 84(5): 477-480
Category: Short Communication
doi: https://doi.org/10.48095/cccsnn2021477

Overview

Introduction: Hearing preservation during vestibular schwannoma surgery is still a challenge even for experienced surgeons. Monitoring of evoked brainstem potentials (brainstem evoked response audiometry; BERA) is one of the standard methods of perioperative hearing evaluation; however, in recent decades, its potential to further improve hearing preservation outcomes has been fully exhausted. Monitoring of direct responses from the cochlear nerve (cochlear nerve action potential; CNAP) is not a widespread technique so far. Direct monitoring informs surgeons almost immediately about the condition of the inner ear and auditory nerve, allowing them to react quickly by changing surgical techniques. Materials and methods: During the February–May 2021 period, we used direct monitoring in 4 patients. An AVALANCHE®XT monitoring unit (Dr. Langer Medical GmbH, Waldkirch, Germany) was used for monitoring, allowing simultaneous monitoring of BERA, CNAP, and the facial nerve. In three patients, the primary goal was to preserve hearing. In the fourth patient with a large tumor, the goal was to track the auditory nerve. Results: Hearing has been preserved in two patients postoperatively. In the first case, both evoked potentials and direct auditory nerve responses were detected at the end of the surgery. In the second case, despite the positive direct responses, the evoked potentials were already not elicited. In the third patient, hearing was not preserved despite elicited evoked responses and direct responses at the end of the procedure. In the fourth patient with a Koose size IV tumor and non-elicited evoked responses from the beginning of the procedure, a direct response from the auditory nerve was detected. The auditory nerve then had to be discontinued due to its infiltration by the tumor. Conclusion: Direct monitoring of the cochlear nerve provides the surgeon with real-time information about the state of hearing during vestibular schwannoma surgery. This method could also be more sensitive in predicting postoperative hearing preservation compared to evoked potentials. Simultaneously with the use of a monitoring probe, it makes it possible to trace the auditory nerve even in the case of larger tumors, in which the success rate in hearing preservation is still very low.

Keywords:

vestibular schwannoma – hearing preservation – direct monitoring

Sources

1. Betka J, Zverina E, Lisy J et al. Vestibulární schwannom. Otorinolaryng a Foniat 2008; 57 (4): 221–225.

2. Yamakami I, Yoshinori H, Saeki N et al. Hearing preservation and intraoperative auditory brainstem response and cochlear nerve compound action potential monitoring in the removal of small acoustic neurinoma via the retrosigmoid approach. J Neurol Neurosurg Psychiatry 2009; 80 (2): 218–227. doi: 10.1136/jnnp.2008.156 919.

3. Legatt AD. Mechanisms of intraoperative brainstem auditory evoked potential changes. J Clin Neurophysiol 2002; 19 (5): 396–408. doi: 10.1097/00004691-200210000-00003.

4. Gama C. Acoustic neuroma surgery with preservation of hearing and vestibular branch of sacrifice. Arq Neuropsiquiatr 1949; 7 (3): 314–320. doi: 10.1590/s000 4-282x1949000300007.

5. Noudel R, Riberio T, Roche PH. Microsurgical treatment of intracanalicular vestibular schwannomas. Prog Neurol Surg 2008; 21: 183–191. doi: 10.1159/ 000156 555.

6. Zvĕřina E, Fusek I, Kunc Z et al. První zkušenosti s mikrochirurgií nádorů n. VIII. Cesk Slov Neurol N 1983; 46/79 (5): 287–292.

7. Šmilauer T, Kluh J, Zvěřina E et al. Přínos BERA k diagnostice neurinomu akustiku. Otorinolaryng a Foniat 2001; 50 (2): 99–102.

8. Fik Z, Chovanec M, Zverina E et al. Funkce lícního nervu po mikrochirurgické léčbě vestibulárního schwannomu. Cesk Slov Neurol N 2017; 80/113 (5): 545–551. doi: 10.14735/amcsnn2017545.

9. Matthies C, Samii M. Management of vestibular schwannomas (acoustic neuromas): the value of neurophysiology for evaluation and prediction of auditory function in 420 cases. Neurosurgery 1997; 40 (5): 919–929. doi: 10.1097/00006123-199705000-00007.

10. Kanzaki J, Tos M, Sanna M et al. New and modified reporting systems from the consensus meeting on systems for reporting results in vestibular schwannoma. Otol Neurotol 2003; 24 (4): 642–648. doi: 10.1097/00129492-200307000-00019.

11. Moller AR, Jannetta PJ. Comparison between intracranially recorded potentials from the human auditory nerve and scalp recorded auditory brainstem responses (ABR). Scand Audiol 1982; 11 (1): 33–40. doi: 10.3109/01050398209076197.

12. Linden RD, Tator CH, Benedict C et al. Electrophysiological monitoring during acoustic neuroma and other posterior fossa surgery. Can J Neurol Sci 1988; 15 (1): 73–81. doi: 10.1017/s0317167100027232.

13. Yamakami I, Oka N, Yamaura A. Intraoperative monitoring of cochlear nerve compound action potential in cerebellopontine angle tumour removal. J Clin Neurosci 2003; 10 (5): 567–570. doi: 10.1016/s0967-5868 (03) 00 143-7.

14. Aihara N, Murakami S, Watanabe N et al. Cochlear nerve action potential monitoring with the microdissector in vestibular schwannoma surgery. Skull Base 2009; 19 (5): 325–332. doi: 10.1055/s-0029-1220 208.

15. Watanabe N, Ishii T, Fujitsu K et al. Intraoperative cochlear nerve mapping with the mobile cochlear nerve compound action potential tracer in vestibular schwannoma surgery. J Neurosurg 2018; 1–8. doi: 10.3171/2017.12.JNS171545.

16. Ishikawa K, Yasui N, Mineura K et al. Significance of hearing preservation in acoustic neuroma surgery. Acta Otolaryngol Suppl 1998; 537: 16–19. doi: 10.1080/00016489850182297-1.

17. Sass HCR, Miyazaki H, West N et al. Extended retrolabyrinthine approach: results of hearing preservation surgery using a new system for continuous near real-time neuromonitoring in patients with growing vestibular schwannomas. Otol Neurotol 2019; 40 (5S Suppl 1): S72–S79. doi: 10.1097/MAO.0000000000002 216.

18. Ishikawa M, Kojima A, Terao S et al. Cochlear nerve action potential monitoring for preserving function of an unseen cochlear nerve in vestibular schwannoma surgery. World Neurosurg 2017; 106: 1057.e1051–1057.e1057. doi: 10.1016/j.wneu.2017.07.113.

19. Roberson JB Jr, Jackson LE, McAuley JR. Acoustic neuroma surgery: absent auditory brainstem response does not contraindicate attempted hearing preservation. Laryngoscope 1999; 109 (6): 904–910. doi: 10.1097/00005537-199906000-00012.

20. Chovanec M, Zvěřina E, Kluh J et al. Zachování sluchu při mikrochirurgické léčbě vestibulárního schwannomu. Cesk Slov Neurol N 2015; 78/111 (4): 435–441.