gms | German Medical Science

56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)
3èmes journées françaises de Neurochirurgie (SFNC)

Deutsche Gesellschaft für Neurochirurgie e. V.
Société Française de Neurochirurgie

07. bis 11.05.2005, Strasbourg

Traintime as a quantitative EMG parameter for facial nerve function during surgery in the cerebellopontine angle

Trainzeit als quantitativer EMG-Parameter zur Beurteilung der Fazialisfunktion in der Kleinhirnbrückenwinkelchirurgie

Meeting Abstract

  • corresponding author J. Prell - Neurochirurgische Klinik, Universitätsklinikum Erlangen-Nürnberg
  • S. Rampp - Neurozentrum, Universitätsklinikum Erlangen-Nürnberg
  • J. Romstöck - Neurochirurgische Klinik, Universitätsklinikum Erlangen-Nürnberg
  • R. Fahlbusch - Neurochirurgische Klinik, Universitätsklinikum Erlangen-Nürnberg
  • C. Strauss - Neurochirurgische Klinik, Universitätsklinikum Erlangen-Nürnberg

Deutsche Gesellschaft für Neurochirurgie. Société Française de Neurochirurgie. 56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 3èmes journées françaises de Neurochirurgie (SFNC). Strasbourg, 07.-11.05.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc10.05.-14.01

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

Published: May 4, 2005

© 2005 Prell 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.




The authors describe a quantitative warning parameter for intraoperative monitoring of the facial nerve during surgery of acoustic neuroma. This parameter, which was called “traintime”, was assessed automatically by a dedicated software program. It was correlated with postoperative clinical outcome in order to demonstrate its clinical significance.


40 patients who underwent surgery on acoustic neuroma were examined. During the entire operative procedure free-running EMG-signals were recorded from muscles targeted by the facial nerve. A software program, specifically designed for this purpose, analyzed these continuous recordings off-line. The program was developed to detect A-trains, a specific pattern of EMG-activity, which is known to be associated with postoperative facial nerve paresis. The parameter traintime was assessed in summing up the intervals of time during which A-trains occurred.


A strong correlation between the length of traintime measured in seconds and deterioration of postoperative facial nerve function was demonstrated. Certain, consecutive thresholds were defined. Their transgression reliably indicated postoperative paresis of the facial nerve and its extent. Differences between the impact of traintime on patients with, respectively without preoperative paresis were observed.


Traintime as a quantitative warning parameter was shown to be a reliable indicator of facial nerve paresis in surgery for acoustic neuromas. Online assessment in the operating room can improve the quality of surgery by keeping the surgeon constantly informed about the condition of the facial nerve, thus enabling him to adapt the operative strategy to the facial nerve’s functional integrity.