gms | German Medical Science

58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

26. bis 29.04.2007, Leipzig

Transcortical high frequency repetitive electrical stimulation for recording of myogenic motor evoked potentials during spinal surgery: the necessity of high-voltage stimulation

Transkortikale elektrische Hochfrequenz-Stimulation zur Ableitung der MEP während spinaler Eingriffe: die Notwendigkeit der Hochvoltstimulation

Meeting Abstract

  • corresponding author M. Morgalla - Neurochirurgische Klinik, Universitätsklinikum Tübingen
  • H. Demirdelen - Neurochirurgische Klinik, Universitätsklinikum Tübingen
  • D. Doischer - Neurochirurgische Klinik, Universitätsklinikum Tübingen
  • M. Liebsch - Neurochirurgische Klinik, Universitätsklinikum Tübingen
  • M. Tatagiba - Neurochirurgische Klinik, Universitätsklinikum Tübingen

Deutsche Gesellschaft für Neurochirurgie. 58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC). Leipzig, 26.-29.04.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. DocSO.01.06

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

Published: April 11, 2007

© 2007 Morgalla 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: Intraoperative monitoring of motor potentials (MEP) during surgery of the spine and spinal cord has become more reliable since the introduction of transcortical high frequency repetitive electrical stimulation. However, in our patients, the normal standard stimulation intensity of 400V was repeatedly insufficient for eliciting peripheral compound potentials. We therefore, compared standard (0 - 400V) and high voltage stimulation (400 - 1000V) prospectively.

Methods: Forty one patients (24 male, 17 female, age 16- 80 years, mean age 52,6 years) with spinal tumors (73% extramedullary, 27% intramedullary) were examined. The patients were anaesthesized with propofol±nitrous oxide. Standard MEPs were elicited by transcortical stimulation of 5 pulsed trains of 500 Hz with an interpulse interval (IPI) of 2ms at C3 and C4. Compound muscle action potentials (CMAP) were recorded with needle electrodes from the anterior tibial and the thenar and hypothenar muscles. The voltage during measurement was increased until reliable potentials appeared and this was compared to later stimulations during surgery. A high voltage stimulator (Multipulse Digitimer D 185-MK IIa) was used (0 to 1000 V).

Results: Three quarters of the patients had preoperative MEP examinations for comparison. In all patients intraoperative MEP potentials could be recorded prior to surgery. In 39% of the patients, a stimulation up to 400V was sufficient for monitoring during the whole period of surgery. In 34% of the patients, initial potentials were recordable under 400 V but during surgery more than 400 V (up to 600V) were necessary. In 27% of the patients, more than 400V were needed from the beginning of the monitoring in order to measure reliable CMPA. In 28% of the patients voltage had to be increased over 700V during surgery. Intramedullary spinal tumors seemed to require a higher voltage for sufficient recording than extramedullary tumors.

Conclusions: Intraoperative spinal MEP monitoring with transcortical high frequency repetitive stimulation will benefit further from high voltage stimulation.