Holsheimer J
Department of Electrical Engineering, University of Twente, Enschede, The Netherlands.
Neurosurgery. 1997 May;40(5):990-6; discussions 996-9. doi: 10.1097/0006123-199705000-00023.
A major drawback of currently available spinal cord stimulation (SCS) systems for the management of chronic intractable pain, especially of widespread pain patterns as in reflex sympathetic dystrophy, is the generally limited paresthesia coverage. The aim of this study is to analyze the origin of this problem and to provide solutions.
Results from theoretical studies, in which a computer model was used to mimic the effects of SCS on spinal nerve fibers, were used to analyze which factors may limit paresthesia coverage. Model predictions were verified by empirical data from clinical literature.
When using common SCS electrodes, both perception threshold and motor/discomfort threshold are generally related to dorsal root stimulation. Because these thresholds have a small ratio (approximately 1:1.4), stimulation of dorsal column fibers and paresthesia coverage is limited by this small range of stimulation. When the distance between the epidural electrode and spinal cord is large (midthoracically), the threshold for dorsal column stimulation exceeds discomfort threshold, resulting only in segmental paresthesia. The range of dorsal column stimulation and paresthesia coverage can be improved when using either an optimally dimensioned rostrocaudal bi-/tripole or a transverse tripole ("guarded cathode"). When applying the latter in combination with a dual channel pulse generator providing simultaneous pulses, paresthesias can simply be changed to optimally cover the painful area.
Paresthesia coverage and pain management by SCS can be improved when using electrodes as proposed.
目前用于治疗慢性顽固性疼痛，尤其是反射性交感神经营养不良等广泛疼痛模式的脊髓刺激（SCS）系统的一个主要缺点是感觉异常覆盖范围通常有限。本研究的目的是分析该问题的根源并提供解决方案。
利用理论研究结果（其中使用计算机模型模拟SCS对脊神经纤维的影响）来分析哪些因素可能限制感觉异常覆盖范围。模型预测通过临床文献中的经验数据进行验证。
使用普通SCS电极时，感知阈值和运动/不适阈值通常都与背根刺激有关。由于这些阈值的比值较小（约为1:1.4），背柱纤维的刺激和感觉异常覆盖范围受到这个较小刺激范围的限制。当硬膜外电极与脊髓之间的距离较大（胸中段）时，背柱刺激的阈值超过不适阈值，仅导致节段性感觉异常。使用尺寸优化的头尾向双极/三极电极或横向三极电极（“保护阴极”）时，背柱刺激范围和感觉异常覆盖范围可以得到改善。当将后者与提供同步脉冲的双通道脉冲发生器结合使用时，感觉异常可以简单地改变以最佳覆盖疼痛区域。
使用所提出的电极时，SCS的感觉异常覆盖范围和疼痛管理可以得到改善。
