Holsheimer J, Barolat G, Struijk J J, He J
Institute for Biomedical Technology, University of Twente, Enschede, The Netherlands.
Acta Neurochir Suppl. 1995;64:119-24. doi: 10.1007/978-3-7091-9419-5_26.
The effects of the antero-posterior and medio-lateral positions of the spinal cord in the dural sac on the perception threshold and paresthesia coverage in spinal cord stimulation were analyzed. The distributions of the dorsal cerebrospinal fluid (CSF) layer thickness, measured from transverse MR scans of normal subjects at various spinal levels, were used to calculate the distributions of threshold voltages for the stimulation of spinal nerve fibers by a computer model. These theoretical threshold distributions were shown to fit well to the corresponding distributions of perception threshold measured in patients. It is concluded that the thickness of the dorsal csf layer is the main factor determining the perception threshold and paresthesia coverage in spinal cord stimulation: an increasing thickness raises the threshold and reduces the coverage, and vice versa. The effects of an asymmetrical electrode position with respect to the spinal cord midline were also analyzed by computer modeling. It is concluded that a lateral asymmetry of less than 1 mm gives a significant reduction of perception threshold and may result in unilateral paresthesiae.
分析了硬脊膜囊中脊髓前后位和内外侧位对脊髓刺激中感觉阈值和感觉异常覆盖范围的影响。利用从正常受试者不同脊髓节段的横向磁共振扫描测量得到的背侧脑脊液（CSF）层厚度分布，通过计算机模型计算刺激脊神经纤维的阈值电压分布。这些理论阈值分布与患者测量得到的相应感觉阈值分布拟合良好。得出结论：背侧脑脊液层厚度是决定脊髓刺激中感觉阈值和感觉异常覆盖范围的主要因素：厚度增加会提高阈值并减少覆盖范围，反之亦然。还通过计算机建模分析了电极相对于脊髓中线的不对称位置的影响。得出结论：小于1毫米的侧向不对称会显著降低感觉阈值，并可能导致单侧感觉异常。
