gms | German Medical Science

59th Annual Meeting of the German Society of Neurosurgery (DGNC)
3rd Joint Meeting with the Italian Neurosurgical Society (SINch)

German Society of Neurosurgery (DGNC)

1 - 4 June 2008, Würzburg

Loss of AEP as a risk of endoscopic assistance in vestibular schwannoma surgery

Verlust der AEP als ein Risiko der endoskopischen Assistenz bei der Operation von Vestibularisschwannomen

Meeting Abstract

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  • corresponding author J. Oertel - Klinik für Neurochirurgie, Krankenhaus Hannover Nordstadt, Hannover, Deutschland
  • M. R. Gaab - Klinik für Neurochirurgie, Krankenhaus Hannover Nordstadt, Hannover, Deutschland

Deutsche Gesellschaft für Neurochirurgie. Società Italiana di Neurochirurgia. 59. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 3. Joint Meeting mit der Italienischen Gesellschaft für Neurochirurgie (SINch). Würzburg, 01.-04.06.2008. Düsseldorf: German Medical Science GMS Publishing House; 2008. DocMI.02.07

The electronic version of this article is the complete one and can be found online at:

Published: May 30, 2008

© 2008 Oertel et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: The indication for endoscope-assisted surgery in vestibular schwannoma surgery is under debate. In most cases, the potential disadvantages of the endoscopic technique are considered to be that it is time consuming and that there is the risk of injury to the delicate structures by the endoscopic equipment. However, the authors observed an additional potential hazard of the endoscopic equipment for hearing preservation in vestibular schwannoma patients.

Methods: Since January 2003, 34 patients with good hearing function and preserved acoustic evoked potential recording (AEP) underwent surgery for vestibular schwannoma via a rectosigmoid suboccipital approach by one of the authors. After microsurgical tumor removal, in all cases a 4mm 45° endoscope optic was employed for the evaluation of tumor removal. AEP preservation as well as postoperative hearing function were closely monitored. In addition, the value of the endoscope with respect to the identification of tumor remnants and opening of the inner ear structure as well as potential side effects were evaluated.

Results: Out of the 34 patients, hearing function as well as AEP were lost during microsurgical tumor resection in 15 cases (44%). After microsurgical tumor resection, endoscopic inspection revealed tumor remnants in 2 cases (6%) which had been removed under endoscopic assistance. In 32 of 34 cases (94%), no remaining tumor mass was found. In 7 out of 19 cases (37%) with preserved AEP after microsurgical tumor removal, a worsening of the AEP was found during endoscopic inspection although no contact to the nerve occurred and irrigation was continuously applied. Out of these 7 cases, AEP loss was transient in 3 and permanent in 4. All four patients demonstrated complete hearing loss postoperatively.

Conclusions: All in all, the authors consider endoscopic assistance to be a valuable tool in selected cases of skull base procedures. However, the endoscopic technique obviously carries potential hazards such as hearing loss. Thus, the application of the endoscope is only justified if there is a high probability of tumor tissue remaining within the inner auditory canal.