gms | German Medical Science

56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)
3èmes journées françaises de Neurochirurgie (SFNC)

Deutsche Gesellschaft für Neurochirurgie e. V.
Société Française de Neurochirurgie

07. bis 11.05.2005, Strasbourg

Electrical excitability of the frontal cortex

Elektrische Erregbarkeit des frontalen Kortex

Meeting Abstract

Suche in Medline nach

  • corresponding author T. Kombos - Neurochirurgische Klinik, Charité - Universitätsmedizin Berlin, Campus Benjamin-Franklin
  • O. Süss - Neurochirurgische Klinik, Charité - Universitätsmedizin Berlin, Campus Benjamin-Franklin
  • M. Brock - Neurochirurgische Klinik, Charité - Universitätsmedizin Berlin, Campus Benjamin-Franklin

Deutsche Gesellschaft für Neurochirurgie. Société Française de Neurochirurgie. 56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 3èmes journées françaises de Neurochirurgie (SFNC). Strasbourg, 07.-11.05.2005. Düsseldorf, Köln: German Medical Science; 2005. DocP042

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgnc2005/05dgnc0310.shtml

Veröffentlicht: 4. Mai 2005

© 2005 Kombos et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective

Contrary to the general clinical view, there is considerable overlapping of primary motor units over a cortical area much broader than the “classical” narrow motor strip along the central sulcus. In the present study, direct cortical stimulation was applied to determine the electrical excitability of the frontal cortex.

Methods

Electrical stimulation of the frontal cortex was performed in 35 patients during surgery in the central region. The central sulcus (CS) was identified by somatosensory evoked potential (SEP) phase reversal. Cortical motor mapping was first performed by monopolar anodal stimulation with a train of 500 Hz (7 - 10 pulses) followed by bipolar stimulation (pulses at 60 Hz with max. 4 sec train duration). Surgery was performed under general anesthesia without muscle relaxants. Action potentials were recorded from the forearm flexor, thenar and quadriceps muscles contra- and ipsilateral to the side of stimulation. The motor areas identified were divided into three categories: (1st): areas located in the primary motor cortex (PMC), which defined as Brodmann areas 4 and 6aα; (2nd): areas located in the secondary motor cortex (SMC), defined as Brodmann areas 6aβ and 8 and (3rd): areas located in the supplementary motor cortex (SuMC), defined as Brodmann areas 9, 45, 44.

Results

Of 315 motor responses elicited by electrical cortical stimulation, 51.5% (162) were located in the PMC, 44.4% (140) outside the motor strip in the SMC, and 4.1% (13) in the SuMC. In all the motor responses from the PMC (162/162) action potentials were recorded only from the contralateral muscles, whereas in 35/140 of the responses from the SMC action potentials were recorded from the ipsilateral muscles.

Conclusions

There is a high concentration of pyramidal cells in the precentral gyrus but also a significant number distributed throughout the frontal and parietal lobe. Contrary to the general clinical view, there is considerable overlapping of motor units over a cortical area much broader than the “classical” narrow motor strip along the central sulcus. Thus anatomic orientation must, whenever possible, be complemented by intraoperative mapping of all these areas in order to prevent postoperative motor deficits.