Eshel Y, Witman S, Rosenfeld M, Abboud S
Medical Physics Group, School of Physics, Faculty of Exact Sciences, Tel Aviv University, Israel.
IEEE Trans Biomed Eng. 1995 Mar;42(3):242-9. doi: 10.1109/10.364510.
The contribution of asymmetric skull thickness to the scalp potential amplitude was investigated numerically. The model consisted of four conductive layers representing the scalp, the skull, the cerebrospinal fluid, and the cortex with a current dipole in the occipital region. The potential created by the dipole was calculated assuming quasistatic formulation and linear media. The governing equation was discretized by the finite volume method to ensure the conservation of fluxes even in regions with abrupt changes of the conductivity. The large set of the algebraic equations for the electric potential was solved iteratively by the successive overrelaxation method. The model confirmed previous experimental studies suggesting that the potential amplitude is 60% smaller on the side with the thicker bone if the asymmetry of the skull thickness exceeds 40%. The model developed suggests that skull thickness asymmetry can create nonnegligible asymmetries in the potential measured on the scalp above homotopic points of the two hemispheres.
通过数值方法研究了不对称颅骨厚度对头皮电位幅度的影响。该模型由四个导电层组成，分别代表头皮、颅骨、脑脊液和皮质，枕区有一个电流偶极子。假设为准静态公式和线性介质，计算偶极子产生的电位。控制方程采用有限体积法离散化，以确保即使在电导率突变的区域也能守恒通量。通过逐次超松弛法迭代求解大量关于电位的代数方程。该模型证实了先前的实验研究，表明如果颅骨厚度不对称超过40%，较厚骨头一侧的电位幅度要小60%。所开发的模型表明，颅骨厚度不对称会在两个半球同位点上方头皮上测量的电位中产生不可忽略的不对称。
