gms | German Medical Science

63rd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Japanese Neurosurgical Society (JNS)

German Society of Neurosurgery (DGNC)

13 - 16 June 2012, Leipzig

Mapping of the perioral region by neuronavigated transcranial magnetic stimulation (nTMS): Mental muscle superior to orbicularis oris muscle for MEP recordings. A technical note

Meeting Abstract

  • C. Weiss - Klinik für Allgemeine Neurochirurgie, Universitätsklinikum Köln; Max-Planck-Institut für Neurologische Forschung, Köln
  • V. Neuschmelting - Klinik für Allgemeine Neurochirurgie, Universitätsklinikum Köln
  • A. Eisenbeis - Klinik für Allgemeine Neurochirurgie, Universitätsklinikum Köln
  • C. Nettekoven - Max-Planck-Institut für Neurologische Forschung, Köln
  • A.K. Rehme - Max-Planck-Institut für Neurologische Forschung, Köln
  • C. Grefkes - Klinik und Poliklinik für Neurologie, Universitätsklinikum Köln; Max-Planck-Institut für Neurologische Forschung, Köln
  • R. Goldbrunner - Klinik für Allgemeine Neurochirurgie, Universitätsklinikum Köln

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 63. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie (JNS). Leipzig, 13.-16.06.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. DocFR.10.02

doi: 10.3205/12dgnc245, urn:nbn:de:0183-12dgnc2455

Published: June 4, 2012

© 2012 Weiss 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: Functional brain mapping is an important presurgical tool for optimized resection planning of brain tumors in eloquent locations. In addition to functional MRI, motor mapping by navigated Transcranial Magnetic Stimulation (nTMS) has been established for clinical routine in recent years. Facial mapping by nTMS is often limited by direct stimulation effects of facial and trigeminal nerve fibres. This direct effect is dose-dependent. Therefore stimulating should be carried out at the lowest amplitudes possible. We therefore compared the most frequently used muscles for mapping of the mouth area, i.e. the mental muscle and the orbicular oris muscle in respect to test-retest-reliability and feasibiltiy.

Methods: We examined 11 healthy subjects on 3 different days within 6 weeks by single pulse nTMS using eXimia 3.2 for simultaneous mapping of the orbicular oris muscle (OO) and the mental muscle (MM). Registration mismatches > 3 mm were not accepted. MEPs were recorded by surface EMG electrodes and latency-corrected (latencies accepted from 7–16 ms). Stimulation was primarily performed at rest, at 110% output compared to the resting motor threshold of the corresponding area [RMT]; if the RMT could not be determined due to direct stimulation, mapping was performed at 95% of direct motor threshold with muscular pre-contraction.

Results: Facial mapping of the mouth was possible in 8/11 subjects. In 3/11 subjects reproducible mapping was not possible due to direct stimulation effects. The mean latency was 10–11 ms, independent of muscular pre-contraction (21 investigations at rest / 21 investigations at pre-contraction; mean latency MM at rest 10.69 ms, MM pre-contracted 11.03 ms, OO at rest 11.33 ms, OO pre-contracted 10.96 ms). Stimulating both muscles simultaneously, the RMT was usually lower for mental muscle (75% of cases), the number of positive stimuli (amplitude > 50 uV) was significantly higher using the mental muscle (mean/session: MM 380 stimuli / OO muscle 273 stimuli) and the mean amplitude was higher (MM: 458 uV / OO: 342 uV). Intersession reliabilities of both methods were comparable.

Conclusions: Presurgical mapping of the perioral region by nTMS was feasible in 75% of healthy subjects. The mentalis muscle mapping seems to be technically superior to the mapping of the orbicularis oris muscle but still often requires muscular pre-contraction.