gms | German Medical Science

55. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)
1. Joint Meeting mit der Ungarischen Gesellschaft für Neurochirurgie

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

25. bis 28.04.2004, Köln

Correlation between intra-operative emg and post-operative facial nerve function in cerebello-pontine-angle surgery - Long-term follow-up

Korrelation des intraoperativen EMG mit postoperativer Fazialisfunktion im Langzeitverlauf bei Kleinhirnbrückelwinkeltumoren

Meeting Abstract

  • corresponding author Meike Manthey - Neurochirurgische Klinik, Georg-August-Universität, Göttingen
  • O. Crome - Neurologische Klinik, Georg-August-Universität, Göttingen
  • A. Sepehrnia - Neurochirurgische Klinik, Clemenshospital Münster, Münster
  • H. Arnold - Neurochirurgische Klinik, Universitätsklinikum Schleswig-Holstein, Campus Lübeck, Lübeck

Deutsche Gesellschaft für Neurochirurgie. Ungarische Gesellschaft für Neurochirurgie. 55. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 1. Joint Meeting mit der Ungarischen Gesellschaft für Neurochirurgie. Köln, 25.-28.04.2004. Düsseldorf, Köln: German Medical Science; 2004. DocDI.02.06

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

Published: April 23, 2004

© 2004 Manthey 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.




During continous intraoperative electromyography from muscles innervated by the facial nerve in cerebello-pontine-angle surgery, potentials quite similar to pathologic spontaneous activity can be registrated. Distinct highfrequent repetitive discharges, called a-trains, has been identified as a predictive marker for occurrence or increase of a facial paresis after operation. The aim of this study was to examine a possible quantitative correlation between the intraoperative emg and the postoperative function of the facial nerve.


In 20 patients continous intraoperative emg –monitoring was performed from the m.orbicularis oris and the m. orbicularis oculi. The recorded data were analyzed by quantitative and qualitative offline-analysis. The evaluation of facial nerve function was done using the scale of House and Brackmann before surgery as well as three days and one year after the operation.


There were 12 patients without deficit or with worsening of one grade maximum, 8 patients had a worsening of 2-4 grades. A-trains were found in 18 patients, in two cases as a false positive result. No false negative results have been registrated. Taking the number of a-trains as a base, it resulted a hyperbel-like-shaped correlation between the grade of paresis and train number with a critical area corresponding to a steep rise in paresis around 200-250 trains. Below that there was a worsening of one grade maximum. One year follow-up results were similar with respect to this correlation. All other parameters (whole train duration, amplitude and frequency), showed no correlation with the postoperative outcome.


A specificity of 89% and a sensitivity of 100% verify the validity of intraoperatively registrated a-trains. The number of registrated a-trains represents a valuable predictive parameter for direct postoperative and the long-term follow-up results. There seems to be a critical threshold-level. Above this threshold-level regularly a significant worsening in facial-nerve-function appears, while below it, there are no or only functional and cosmetic irrelevant deficits. Thus the amount of intraoperative registrated a-trains may be a worthy tool to identify patients, who might benefit from an early onset vasoactive or neuroprotective therapy even before deficits are registered clinically.