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59. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
3. Joint Meeting mit der Italienischen Gesellschaft für Neurochirurgie (SINch)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

01. - 04.06.2008, Würzburg

Intraoperative monitoring of the cochlear nerve using a tympanic electrode

Intraoperatives Monitoring des N. cochlearis mit ener Tympanon-Elektrode

Meeting Abstract

Suche in Medline nach

  • corresponding author J. Lehmberg - Allgemeine Neurochirurgie, Klinikum der Albert-Ludwigs-Universität, Freiburg
  • S. K. Rosahl - Allgemeine Neurochirurgie, Klinikum der Albert-Ludwigs-Universität, Freiburg

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. DocP 031

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgnc2008/08dgnc299.shtml

Veröffentlicht: 30. Mai 2008

© 2008 Lehmberg et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: Preservation of hearing has become a goal in surgery in the cerebellopontine angle. Intraoperative monitoring of the brainstem auditory evoked response (ABR) is at that time the standard in identification of operative manouvers diminishing the integrity of the eighth nerve. Depending upon the pathology, the ABR may be altered, limiting its evaluation. The electrocochleogram (EchoG) produces potentials nearer to the site of origine, therefore the amplitude is higher in comparison to the ABR. For recording of the EchoG transtympanic needle electrodes and intrameatal spring electrodes are used. In this study, a new tympanic electrode was designed, which should be non-invasive and easily insertible. Potentials of this tympanic electrode were than compared to the ABR, which was simultaneously recorded.

Methods: A spiralspring electrode with a ball at the tip was designed, which was integrated into the ear-plug of the click-generator. Potentials of this tympanic electrode were than compared to the ABR, where a needle electrode at the mastoid was used.

Results: Placing of the electrode onto the tympanic membrane was achieved very easy in 16 patients. No additional instrument for the placement was needed. The tympanic membrane was never penetrated once by the electrode. The amplitude of the compound action potential (CAP) was more than 2.5 times higher than the wave I of the ABR. Fewer responses were needed for averaging, therefore the time for detection of changes in the waveforms was short. The CAP corresponded timely to the wave I in the ABR. Not only the nearfield was recorded by the tympanic electrode, but also the wave III and V. The amplitude of these waves were of the values in both recordings.

Conclusions: The tympanic electrode is an easy and safe tool in intraoperative monitoring of the eighth nerve. The compound action potential of the EcoG is generated at the distal end of the cochlear nerve, and should display functional changes of the nerve during operation. The wave I of the ABR is often poorly displayed with tumours in the cerebellopontine angle and can persist in modified form even after transection of the eighth nerve. An accurate and secure depiction of the CAP is desirable to increase the prognostic value of the CAP compared to the waves III and V of the ABR. The frequent use of the new tympanic electrode will show whether the ECoG can become routine during surgery in the cerebellopontine angle.