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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

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Significance of intraoperative motor function monitoring using transcranial electrical motor evoked potentials (MEP)

Aussagekraft des intraoperativen Monitoring mit transkraniell elektrisch motorisch evozierten Potentialen (MEP)

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  • corresponding author Matthias Krammer - Abteilung für Neurochirurgie, Akademisches Lehrkrankenhaus München Bogenhausen, Englschalkingerstr. 77, 81925 München
  • S. Wolf - Abteilung für Neurochirurgie, Akademisches Lehrkrankenhaus München Bogenhausen, Englschalkingerstr. 77, 81925 München
  • W. Gerstner - Abteilung für Neurochirurgie, Akademisches Lehrkrankenhaus München Bogenhausen, Englschalkingerstr. 77, 81925 München
  • C. B. Lumenta - Abteilung für Neurochirurgie, Akademisches Lehrkrankenhaus München Bogenhausen, Englschalkingerstr. 77, 81925 München

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. DocMO.05.02

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/dgnc2004/04dgnc0054.shtml

Published: April 23, 2004

© 2004 Krammer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Objective

Transcranial intraoperative MEP monitoring in patients with lesions near the motor pathways is thought to be a valuable tool for prevention of new postoperative motor deficits. The aim of this study was to investigate its diagnostic facilities in our patients collective.

Methods

Fifty-nine patients, 21 with spinal (e.g. meningioma, ganglioglioma, metastases, spinal stenosis) and 38 with intracranial lesions (e.g. sphenoid wing meningioma, oligoastrocytoma, AVM) were studied. Transcranial stimulation was performed with a high frequency (500 Hz) electrical train stimulation (train of 5, stimulation rate 0.1 Hz, stimulation intensity max. 100mA/400V, pulse width 0.2-0.7msec) by using two subdermal needle electrodes. MEP were recorded from a forearm flexor, the abductor pollicis brevis, the quadriceps femoris and the anterior tibial muscle. Decreasing amplitudes of more than 50%, increasing latencies of more than 10% and increasing stimulus intensities were reported to the surgeon.

Results

MEP recording of upper limbs was possible in 97.9%, of the lower limbs in 85%. Stimulation intensities had a large variability in voltage and amperage (52V to 400V and 51mA to 100mA, resp.). We saw a temporary maximum amplitude reduction of more than 50% in 26 (44%) patients and 22 (37%) needed an increase in stimulation intensity of more than 20%. Eight of these patients deteriorated in motor function postoperatively. Latencies were completely in normal range. No complications like seizures, infections or skin affections were observed. Intraoperative MEP changes had a sensitivity of 88% and and a specifity of 56%. The positive predictive value of MEP changes for postoperative motor funcion deterioration was 27%, and the negative predictive value was 97%.

Conclusions

Transcranial electrical monitoring of MEP is a practicable and safe method. However, there are many events which can cause amplitude changes of MEP independent from surgical manipulations. Although sensitivity is high, this results in a low specificity of MEP monitoring for prediction of postoperative deterioration of motor function.