gms | German Medical Science

57th Annual Meeting of the German Society of Neurosurgery
Joint Meeting with the Japanese Neurosurgical Society

German Society of Neurosurgery (DGNC)

11 - 14 May, Essen

Traintime and long-term outcome of facial nerve function after acoustic neuroma surgery

Trainzeit und Langzeitergebnisse hinsichtlich der Funktion des N. facialis nach Exstirpation von Akustikusneurinomen

Meeting Abstract

  • corresponding author J. Prell - Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen
  • S. Rampp - Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen
  • J. Romstöck - Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen
  • M. Buchfelder - Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen
  • C. Strauss - Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 57. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. Essen, 11.-14.05.2006. Düsseldorf, Köln: German Medical Science; 2006. DocSO.07.07

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

Published: May 8, 2006

© 2006 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.



Objective: The quantitative warning parameter “traintime” was assessed automatically by a dedicated software program during the surgical procedure in 40 patients treated for acoustic neuroma. The program utilized for the analysis is able 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. It was now correlated with postoperative clinical outcome after one year in order to demonstrate its ability to predict long-term results.

Methods: 40 patients who had undergone surgery for acoustic neuroma and whose intraoperative facial nerve EMG had been recorded and analyzed postoperatively were examined again one year after surgery. The preoperative clinical status of facial nerve function was compared with postoperative functional status after one year.

Results: A strong correlation between the length of traintime measured in seconds and the long-term outcome could be demonstrated. Two groups of patients were formed – with (B), and respectively without (A) preoperative paresis of the facial nerve. In group A, 83% of the patients with less than 50 sec of traintime did not show any paresis in the long-term follow up and all patients with more than 50 sec traintime suffered from persistent paresis. In group B, all patients with less than 10sec of traintime had an unchanged or even improved (71%) facial nerve function one year after the operation. 75% of the patients with more than 10 sec of traintime kept an unchanged facial nerve function or a persistent deterioration of facial nerve function (50%).

Conclusions: Traintime as a quantitative warning parameter has already been shown to be a reliable indicator of facial nerve paresis in surgery for acoustic neuroma. Additionally, it is able to predict the long-term functional results. In patients with pre-existent paresis, a low traintime is associated with a high probability of functional recovery beyond the preoperative state after one year.