Rohde V, Mayfrank L, Weinzierl M, Krings T, Gilsbach J M
Department of Neurosurgery, Aachen University, Germany.
J Neurol Neurosurg Psychiatry. 2003 Sep;74(9):1283-7. doi: 10.1136/jnnp.74.9.1283.
To investigate if intraoperative focused high frequency repetitive transcranial magnetic stimulation (rTMS) can localise the primary motor cortex without exposure of the cortical surface.
A high frequency train (357 Hz) of four suprathreshold magnetic stimuli was delivered transcranially to the region of the rolandic area during brain tumour operations in 12 patients. To induce a focal magnetoelectric field, the flat figure of eight coil (outer diameter of each loop 7 cm) was used. Motor evoked potentials (MEP) were recorded in eight muscles of the upper and lower contralateral extremities. The first stimulation site was 2.5 cm behind the bregma, the second site 2 cm, and the third site 4 cm dorsal to the first stimulation site. If no MEP were obtainable, stimulation was repeated in anteroposterior direction at more laterally located sites. Using neuronavigation, each positive stimulation site was correlated with the underlying cortical anatomy.
Stimulation was performed at a total of 42 sites (in two patients, maximum stimulation at the three initial sites failed to evoke a motor response). In four patients, MEP were obtained only from one stimulation site. This site exactly overlayed the primary motor cortex. In eight patients, MEP could be elicited from more than one stimulation site. In seven of the eight patients, the site from which MEP with peak amplitudes were elicited, corresponded to the primary motor cortex. In total, the primary motor cortex was correctly identified on the basis of electrophysiological findings in 11 of 12 patients (92 %). In two patients, only the more lateral stimulation sites permitted MEP recording.
Intraoperative focused rTMS is highly sensitive for localisation of the primary motor cortex. Focused rTMS as a localising instrument alleviates the need of motor cortex exposure and, thereby, can contribute to minimise the surgical approach to brain tumours in the rolandic area.
研究术中聚焦高频重复经颅磁刺激（rTMS）能否在不暴露皮质表面的情况下定位初级运动皮层。
在12例脑肿瘤手术过程中，经颅向中央前回区域给予一列高频（357Hz）的4个阈上磁刺激。为诱导局灶性磁电场，使用了外径为7cm的八字形扁平线圈。在对侧上下肢的8块肌肉中记录运动诱发电位（MEP）。第一个刺激部位位于前囟后2.5cm，第二个部位位于第一个刺激部位背侧2cm，第三个部位位于第一个刺激部位背侧4cm。如果未获得MEP，则在更外侧的部位沿前后方向重复刺激。使用神经导航，将每个阳性刺激部位与下方的皮质解剖结构进行关联。
共在42个部位进行了刺激（2例患者在最初的3个部位进行最大刺激未能诱发运动反应）。4例患者仅从一个刺激部位获得MEP。该部位恰好覆盖初级运动皮层。8例患者可从多个刺激部位引出MEP。在这8例患者中的7例中，引出峰振幅MEP的部位对应于初级运动皮层。总共，根据电生理结果在12例患者中的11例（92%）中正确识别出了初级运动皮层。2例患者仅在更外侧的刺激部位记录到了MEP。
术中聚焦rTMS对初级运动皮层的定位高度敏感。聚焦rTMS作为一种定位工具减轻了暴露运动皮层的需求，从而有助于将对中央前回区域脑肿瘤的手术入路降至最低。
