gms | German Medical Science

70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

12.05. - 15.05.2019, Würzburg

DNAP monitoring in vestibular schwannoma surgery – In which tumour size is it helpful?

DNAP Monitoring in der Vestibularis-Schwannom-Operation – Bei welcher Tumorgröße ist es nützlich?

Meeting Abstract

  • presenting/speaker Matthias Fischer - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland
  • Maike Filsinger - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland
  • Mario Löhr - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland
  • Ralf-Ingo Ernestus - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland
  • Cordula Matthies - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland
  • Maria Breun - Uniklinikum Würzburg, Neurochirurgie, Würzburg, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie. Würzburg, 12.-15.05.2019. Düsseldorf: German Medical Science GMS Publishing House; 2019. DocV032

doi: 10.3205/19dgnc044, urn:nbn:de:0183-19dgnc0443

Published: May 8, 2019

© 2019 Fischer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objective: Intraoperative auditory brainstem monitoring (ABR) monitoring during vestibular schwannoma (VS) resection is susceptible for electrical interference and requires time consuming averaging. As an alternative, direct monitoring of the nerve action potential (DNAP) was tested. This pilot study analyses the features of DNAP monitoring and its utility according to different tumor extensions.

Methods: Within a prospective multi-modality study on retro-sigmoid VS surgery, 16 patients (8 male, 8 female, mean age 44 y) were selected for ABR and DNAP monitoring. Inclusion criteria were pre-operative hearing (H2 or H3 by Hannover Classification) and preserved ABR results preoperative. Tumor extension was small in 5 cases (T2), medium in 8 cases (T3A 6x, T3B 2x) and large (T4) in 3 cases. DNAP monitoring was performed with a 5.5 x 3.0 mm platinum electrode positioned either at the dorsal cochlear nucleus or at the proximal part of the cochlear nerve.

Results: DNAP monitoring, shows about ten times higher amplitudes and is available after a very low number of averaging (<100). The wave pattern is similar to ABR. The major difference is that the peaks of waves I and II are inverted in DNAP monitoring. The latencies of the components are comparable in DNAP and ABR. In our experience, DNAP monitoring was very helpful in 10 cases: In three cases (1x T2 and 2x T3A) DNAP worked perfectly well, but the ABR was also stable and retrospectively hearing preservation could have been achieved without DNAP. In seven cases (3x T2, 4x T3A) ABR was already deteriorated when DNAP monitoring could be started, but with DNAP the remaining waves could be continuously monitored and preserved, so that in five of seven cases a good (H1 or H2) hearing function could be preserved. The advantage was that with DNAP more remaining wave components could be detected than with ABR. In six cases, DNAP was not helpful (1x T2, 2x T3B and 3x T4): In 4 large tumors (T4 or T3B), electrode placement was possible too late; in 2 cases, DNAP was disturbed by artefacts and could document only a rapid loss of the potentials.

Conclusion: Additional DNAP monitoring during VS resection is most beneficial in small and medium sized tumors (T2 and T3A). If deterioration happens in these cases DNAP could show a reproducible remaining potential, which is worth to preserve, because it is functional. Due to difficulties in electrode placing in large tumors (T3B, T4), the usage is limited.