Silva Leandro Moura, do Nascimento José Jailson Costa, de Lira Bandeira Wigínio Gabriel, de Araújo-Neto Severino Aires, de Oliveira Hunt Shannon, Beserra Diniz Paula Rejane
Department of Anatomy, Federal University of Pernambuco, Recife, Brazil.
Postgraduate Program in Structural and Functional Biology, Federal University of Rio Grande do Norte, Natal, Brazil.
Brain Topogr. 2025 Aug 25;38(5):59. doi: 10.1007/s10548-025-01141-y.
The international 10-20 system's C3/C4 positions are standard for locating the primary motor hand area (M1-HAND) in tDCS and as TMS motor mapping references. While cost-effective, their accuracy for M1-HAND localization is limited as compared to specialized methods. This study aimed to establish a novel position within the 10-20 system for accurately identifying the anatomical hand knob, thereby providing an accurate indirect reference for the M1-HAND. We analyzed 116 MRI scans to define standardized X and Y coordinates representing the scalp projection of the anatomical hand knob. These coordinates were converted into percentages (X% and Y%) based on the nasion-inion and tragus-to-tragus distances, respectively. Initial testing revealed X% didn't improve accuracy and thus was excluded. However, Y% (13% of the tragus-to-tragus distance) significantly enhanced targeting by shifting the optimal site medially relative to C3/C4 placements. We then evaluated the accuracy of this new position against C1/C2, C3h/C4h, and C3/C4. While X coordinates of the corresponding anatomical area of the hand knob on the scalp and C3/C4 positions were similar, their Y coordinates differed significantly. The new position (hand knob position) demonstrated the closest proximity to the anatomical hand knob area on the scalp among all evaluated positions. Our study establishes an accurate position within the 10-20 system for identifying the corresponding anatomical area on the scalp of the hand knob. The Y% value (13% of tragus-to-tragus distance) notably enhances the specificity of M1-HAND localization (via its anatomical correlate) as compared to traditional 10-20 system positions.
国际10-20系统的C3/C4位置是在经颅直流电刺激（tDCS）中定位主要运动手部区域（M1-HAND）以及作为经颅磁刺激（TMS）运动映射参考的标准位置。虽然具有成本效益，但与专门方法相比，它们对M1-HAND定位的准确性有限。本研究旨在在10-20系统内建立一个新的位置，以准确识别解剖学手部旋钮，从而为M1-HAND提供准确的间接参考。我们分析了116例磁共振成像（MRI）扫描，以确定代表解剖学手部旋钮头皮投影的标准化X和Y坐标。这些坐标分别根据鼻根-枕骨和耳屏-耳屏距离转换为百分比（X%和Y%）。初步测试显示X%并未提高准确性，因此被排除。然而，Y%（耳屏-耳屏距离的13%）通过相对于C3/C4位置将最佳位置向内移动，显著提高了靶向性。然后，我们将这个新位置的准确性与C1/C2、C3h/C4h和C3/C4进行了评估。虽然头皮上手部旋钮相应解剖区域的X坐标与C3/C4位置相似，但其Y坐标有显著差异。在所有评估位置中，新位置（手部旋钮位置）显示出与头皮上解剖学手部旋钮区域最接近。我们的研究在10-20系统内建立了一个准确的位置，用于识别头皮上手部旋钮的相应解剖区域。与传统的10-20系统位置相比，Y%值（耳屏-耳屏距离的13%）显著提高了M1-HAND定位的特异性（通过其解剖学关联）。
