gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

Mapping and monitoring of motor cortex in awake craniotomy

Meeting Abstract

  • Andrea Szelényi - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland
  • Ines Kropff - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland
  • Rüdiger Gerlach - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland
  • Hartmut Vatter - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland
  • Ági Oszvald - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland
  • Volker Seifert - Klinik und Poliklinik für Neurochirurgie, Klinikum der Johann Wolfgang Goethe Universität, Frankfurt am Main, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocV1574

DOI: 10.3205/10dgnc049, URN: urn:nbn:de:0183-10dgnc0494

Published: September 16, 2010

© 2010 Szelényi 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: In awake surgery commonly language skills are tested, whereas motor function is often used to determine stimulation intensity. Negative language mapping or patients‘ malcompliance might lead into an asleep-awake-asleep procedure, which anticipates clinical observation. Thus, while tumor resection within the white matter close to the pyramidal tract, imminent injury of perforating arteries resulting in motor deficit may go unnoticed. This study evaluates the feasibility of somatosensory (SEPs) and motor evoked potentials (MEPs).

Methods: Patients undergoing awake craniotomy (sleep-awake sleep fashion) were additionally assessed with standard bilateral median nerve SEPs and MEPs. SEPs were recorded at C3’ resp. C4’ referenced to Fz. MEPs were elicited at C3 resp. C4 referenced to Fz. MEPs were recorded from contralateral hand and arm muscles. After dura opening a 4-8-contact strip electrode was placed on the cortex for SEP and EEG-recording, as well as eliciting MEPs (2-5 anodal pulses, each of 0.2–0.4 ms duration, interstimulus time interval 4 ms, 20 mA at maximum). Warning criteria were an amplitude decrement >50% in either modality compared to baseline obtained to a comparable state of consciousness. SEPs and MEPs of the contralateral side served as control and were tested intermittently.

Results: In all 40 patients (44±13 years, 16 f) SEPs and MEPs were obtained and well tolerated in the opening phase of the surgery. After dura opening, MEPs were evoked direct cortically with the strip electrode without related side effects. In 37 patients, SEPs and MEPs remained unchanged throughout the surgery. None of those patients suffered a new postoperative sensory-motor deficit. In one patient the awakening was prolonged. Simultaneously, an MEP loss was observed and indicated an intratumoral hemorrhage. In the other two patients, sleepiness in the course of the surgery hampered the clinical testing, while MEP losses and SEP amplitude decrement occurred during tumor resection in the mesial border of the tumor. Both patients suffered a new motor deficit with accompanying signal alteration in the postoperative MRI scan. Over a three months period, both patients recovered with a slight hemiparesis.

Conclusions: Standardized median nerve SEPs and MEPs can be obtained during awake craniotomy. This has the benefit of objective methods at hand in case of malcompliance or deterioration of the state of consciousness. This is considered helpful in timely identifying critical surgical steps.