gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Comparison of two methods of electrical stimulation during subcortical glioma resection

Meeting Abstract

  • A. Szelényi - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main
  • M. Jardan - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main
  • M.T. Forster - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main
  • K. Franz - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main
  • H. Vatter - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main
  • V. Seifert - Klinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt/Main

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocMO.06-02

DOI: 10.3205/09dgnc028, URN: urn:nbn:de:0183-09dgnc0287

Published: May 20, 2009

© 2009 Szelényi et al.
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Outline

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Objective: In glioma surgery, subcortical electrical stimulation is used for functional guided resection. There are two stimulation techniques for this purpose: a) the 50 Hz stimulation technique using a bipolar probe and b) multipulse technique using a monopolar probe. Both techniques elicited motor evoked potentials (MEPs) from limb or face muscles. The presence of MEPs guides boundaries of tumor resection. This study compares stimulation intensities necessary to elicit MEPs while using the mono vs. bipolar probes and the 50 Hz and multipulse technique.

Methods: In a group of 12 patients (47±17 years; 6 f; 6m) undergoing intracranial tumor resection, both techniques were used; a) the 50 Hz technique (1 second train of stimuli consisting of biphasic anodal/cathodal pulses, 1 ms pulse duration, 0.1 Hz repetition rate) and b) multipulse technique (5 pulses, 0.5 ms duration, interstimulus interval 4 ms, cathodal stimulation, 0.5 Hz repetition rate). For both techniques a bipolar (1.5 mm ball tip, 8 mm distance) and monopolar probes (1.5 mm diameter tip) were used, the stimulation intensity was limited to 30mA maximum. MEPs were recorded contralaterally to the stimulation hemisphere from abd. pollicis brevis, extensor digit. comm. biceps brachii and tibialis ant. muscles. The stimulation intensities needed to elicit MEPs were determined as motor threshold (MT).

Results: Both techniques were applied in all 12 patients. The monopolar 50 Hz technique elicited MEPs with a MT of 11.8±9mA in 10 patients. The monopolar multipulse technique elicited MEPs with MT of 9.8±3.9 mA in all 12 patients. The bipolar 50 Hz technique elicited MEPs with MT of 16.3±7 mA in 5 patients. The bipolar multipulse technique elicited MEPs with MT of 16.2±10 mA in 4 patients. In those four patients, in whom MEPs were elicitable with both methods the mean MT for the monopolar multipulse technique was 6mA compared to 17.5mA with the bipolar 50 Hz technique, thus being 3 fold (paired t-test=0.008).

Conclusions: With the monopolar probe in either technique (50 Hz/multipulse), the stimulation intensities needed to elicit MEPs are significantly lower compared to the bipolar probe. This results in eliciting MEPs in a higher number of patients. Thus, using the monopolar probe is more suitable for the purpose of identifying the corticospinal tract. This is probably due to the electric field properties created of the bipolar vs. monopolar probe.