Xiao S
Rehabilitation Engineering Centre, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Biomed Sci Instrum. 1997;33:435-40.
The field action potentials are a convolution of source strength and the propagating-point source responses (PPSRs). Surface-recorded peripheral nerve potentials are strongly influenced by the volume-conductor properties of the limb. In this paper the PPSRs are solved based on finite-element formulation, which allows solutions to forward volume-conductor problems involving curved nerves in arbitrarily shaped, inhomogeneous, anisotropic limbs. Effects of limb perturbation on surface-recorded nerve action potentials are simulated based on circular and elliptic cylinders with a uniform cross-section consisting of multiple inhomogeneous and anisotropic regions (fat, muscles, and bone layers). The simulations show that a simple homogeneous model is adequate only for a very superficial nerve that lies completely in the subcutaneous fat layer. Deeper nerves that lie on or within the muscle require a multiple-layer model that takes both the muscle and the fat into account. The cross section only needs to be modeled accurately between the recording site and the nerve location. A circular limb model is adequate for clinical recordings. However, an accurate knowledge of the nerve path is essential for accurate modeling of the action potentials, in both needle and surface recordings.
场动作电位是源强度与传播点源响应（PPSRs）的卷积。表面记录的周围神经电位受肢体容积导体特性的强烈影响。本文基于有限元公式求解PPSRs，这使得能够解决涉及任意形状、不均匀、各向异性肢体中弯曲神经的正向容积导体问题。基于由多个不均匀和各向异性区域（脂肪、肌肉和骨层）组成的具有均匀横截面的圆柱体和椭圆柱体，模拟了肢体扰动对表面记录的神经动作电位的影响。模拟结果表明，简单的均匀模型仅适用于完全位于皮下脂肪层的非常浅表的神经。位于肌肉上或肌肉内的较深神经需要考虑肌肉和脂肪的多层模型。仅需要在记录部位和神经位置之间精确建模横截面。圆形肢体模型适用于临床记录。然而，无论是针电极记录还是表面记录，准确了解神经路径对于动作电位的精确建模至关重要。
