Department of Clinical Neurophysiology, Hospital Del Mar, Barcelona, Spain.
Clin Neurophysiol. 2012 Nov;123(11):2205-11. doi: 10.1016/j.clinph.2012.04.008. Epub 2012 May 22.
To establish a methodology for mapping of primary motor cortex (M1) for cricothyroid (CTHY) muscles in a group of healthy subjects using three-dimensional (3D) magnetic resonance imaging (MRI) navigated transcranial magnetic stimulation (nTMS).
Two independent measurements were performed. Twelve right-handed healthy subjects were included in the study. In the first measurement, mapping of the abductor pollicis brevis (APB) muscle was followed by mapping of the M1 for CTHY. This was performed in 11 subjects. Second, to avoid bias concerning using a hand knob as a landmark, mapping of M1 for CTHY muscle was followed by mapping of M1 for APB. This was performed in three healthy subjects. The nTMS was used, with selective recordings of motor evoked potentials (MEPs) from APB muscle and corticobulbar motor evoked potentials (CoMEPs) from the CTHY muscle. For recording the responses from the CTHY muscle two hook wire electrodes (the size of 76 μm of diametre passing through 27 gauge needle) were inserted in the muscle. For the recording of MEPs from APB muscle, surface electrodes were used.
First measurement: Stimulation over the left M1 for APB muscles elicits MEPs in the contralateral APB muscle with a mean latency of 22.8±1.69ms. Stimulation over the left M1 for the CTHY muscle elicits CoMEPs in the contralateral CTHY muscle with a mean latency of 11.89±1.26ms. The distance between the cortical representation for APB and CTHY was 25.19±6.52mm, with CTHY muscle representation lateral to the APB muscle. Second measurement: The results of second measurement of the distance between M1 for CTHY and M1 for APB and their cortical localisation were comparable to the results of the first measurement.
This is the first study with the aim to determine the exact cortical localisation of CTHY muscle with nTMS. Mapping of M1 for CTHY and APB muscles by nTMS was successfully performed in all healthy subjects. The exact location of the stimulating points over M1 muscles eliciting responses in CTHY and APB muscles was determined and superimposed over 3D MRI images. The data show that M1 for CTHY muscle is about 25mm more lateral with regard to M1 for the APB muscle.
Mapping of M1 for CTHY muscle might represent an important neurophysiologic marker for facilitating preoperative mapping of motor speech-related cortical areas due to the proximity of motor cortical representation for laryngeal muscles and opercular part of the Broca area.
使用三维（3D）磁共振成像（MRI）导航经颅磁刺激（nTMS），为一组健康受试者建立初级运动皮层（M1）映射甲状旁腺肌（CTHY）的方法。
进行了两项独立的测量。研究纳入了 12 名右利手健康受试者。在第一次测量中，先对拇短展肌（APB）进行映射，然后对 CTHY 的 M1 进行映射。在 11 名受试者中进行了此操作。其次，为避免使用手旋钮作为标记的偏差，首先对 CTHY 肌肉的 M1 进行映射，然后对 APB 肌肉的 M1 进行映射。这在三个健康受试者中进行。使用 nTMS，选择性记录来自 APB 肌肉的运动诱发电位（MEP）和来自 CTHY 肌肉的皮质脊髓运动诱发电位（CoMEP）。为了记录 CTHY 肌肉的反应，将两个钩状电（通过 27 号针穿过的 76μm 直径的大小）插入肌肉中。为了记录来自 APB 肌肉的 MEPs，使用表面电极。
第一次测量：刺激左侧 M1 中的 APB 肌肉会在对侧 APB 肌肉中引起 MEP，潜伏期平均值为 22.8±1.69ms。刺激左侧 M1 中的 CTHY 肌肉会在对侧 CTHY 肌肉中引起 CoMEP，潜伏期平均值为 11.89±1.26ms。APB 和 CTHY 肌肉的皮质代表之间的距离为 25.19±6.52mm，CTHY 肌肉代表位于 APB 肌肉的外侧。第二次测量：第二次测量 M1 中的 CTHY 和 M1 之间的距离及其皮质定位的结果与第一次测量的结果相当。
这是第一项旨在通过 nTMS 确定 CTHY 肌肉的确切皮质定位的研究。nTMS 成功地对所有健康受试者进行了 CTHY 和 APB 肌肉的 M1 映射。确定并叠加在 3D MRI 图像上，刺激 M1 肌肉上引起 CTHY 和 APB 肌肉反应的点的精确位置。数据显示，相对于 APB 肌肉的 M1，CTHY 肌肉的 M1 大约向外侧延伸 25mm。
由于喉肌和布罗卡区的口盖部分的运动皮质代表的接近，对 CTHY 肌肉的 M1 进行映射可能代表了一种重要的神经生理标志物，有助于术前对与运动言语相关的皮质区域进行映射。
