gms | German Medical Science

71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

21.06. - 24.06.2020

Protocol for mapping of the supplementary motor area using repetitive navigated transcranial magnetic stimulation

Protokoll zum Mapping des supplementär-motorischen Areals mittels repetitiver transkranieller Magnetstimulation

Meeting Abstract

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  • presenting/speaker Melina Engelhardt - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland; Charité – Universitätsmedizin Berlin, Einstein Centre for Neurosciences, Berlin, Deutschland
  • Jari Karhu - University of Eastern Finnland, Department of Physiology, Kuopio, Finland; Nexstim, Helsinki, Finland
  • Thomas Picht - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland; Humboldt-Universität zu Berlin, Cluster of Excellence Matters of Activity, Berlin, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. sine loco [digital], 21.-24.06.2020. Düsseldorf: German Medical Science GMS Publishing House; 2020. DocV060

doi: 10.3205/20dgnc064, urn:nbn:de:0183-20dgnc0644

Veröffentlicht: 26. Juni 2020

© 2020 Engelhardt et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe



Objective: The supplementary motor area (SMA) has been suggested to mediate movement planning, execution and coordination. Navigated transcranial magnetic stimulation (nTMS) offers the possibility to induce transient lesions of the SMA to study the specific role on this region in performance of motor tasks. Further, it enables a detailed mapping of functionally relevant areas within the SMA, potentially aiding preoperative diagnostics in patients. The aim of this study was the development of a repetitive nTMS protocol for non-invasive functional mapping of the SMA.

Methods: The SMA was mapped in the dominant hemisphere of five healthy subjects (28 ± 8.7 years, 2 females) using repetitive nTMS at 20 Hz (120% RMT), while subjects performed a finger tapping task. The location of induced errors was marked in each subject’s individual MRI. Additionally, a SMA hotspot was defined as the point consistently eliciting the largest disruptions of task performance upon stimulation. To exclude effects due to indirect stimulation of M1, effects of SMA stimulation were directly compared to effects of M1 stimulation in four different tasks (finger tapping, writing, line tracing, pointing at small circles with a pencil). M1 was therefore targeted with the intensity of the residual electric field reaching the motor hotspot during SMA stimulation.

Results: Mapping of the SMA was possible in 4 of 5 subjects. Stimulation of the SMA compared to M1 led to a reduction of finger taps (34.8 ± 7.6 vs. 41.8 ± 3.8 taps), reduced number of circles targeted (15.9 ± 3.6 vs. 17.3 ± 3) as well as increased number of circles missed (3.5 ± 2.3 vs. 1.3 ± 1.1) and less accurate line tracing and writing. Further, effects of SMA disruption increased with stimulation time, while effects were immediately present when stimulating M1.

Conclusion: Mapping of the SMA using repetitive nTMS is feasible in the majority of the subjects. While errors induced in the SMA are not entirely independent of M1 due to the proximity of both regions, disruption of the SMA seems to induce functionally distinct errors. Thus, error maps of the SMA assessed with nTMS can give valuable insights into the functional organization of this region, potentially guiding preoperative diagnostics in patients with brain lesions.