Background

The standard level for lesioning in a functional posterior rhizotomy (FPR) ranges from L2 to S1/S2. Lesioning of the S1 and S2 rootlets strongly correlates with a reduction in ankle spasticity. In the Japanese population, the S2 root often shows the highest dorsal root action potentials (DAPs) in the afferent fibers of the pudendal nerve and is not lesioned to preserve postoperative urinary function. Thus, cutting of the S1 root plays a key role in reducing ankle spasticity in FPR. However, on rare occasions, even an S1 root may show high DAP in the afferent fibers of the pudendal nerve.

Purpose

The present, brief, technical note aimed to describe how an S1 root with a relatively high DAP in the afferent fibers of the pudendal nerve may be handed.

Methods

In the procedure, the S1 root is divided into several rootlets, and each rootlet is tested for the pudendal mapping. A train of electrical stimuli is delivered to each rootlet in the standard FPR. If electromyography (EMG) findings after electrical stimulation are highly abnormal while the pudendal mapping demonstrates no or a relatively low DAPs, the rootlet is cut. In contrast, even if the rootlet shows highly abnormal EMG findings, it is preserved if mapping demonstrates a relatively high DAP.

Conclusion

The S1 pudendal mapping is combined with EMG findings to achieve satisfactory reduction in ankle spasticity while preserving urological function.

中文翻译：

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功能性后根切断术中S1根的阴部映射：当S1后根显示出较高的阴部背侧动作电位时-技术说明

背景

功能性后路神经根切断术（FPR）的损伤标准水平为L2至S1 / S2。S1和S2小根的损伤与脚踝痉挛的减少密切相关。在日本人群中，S2根通常在阴部神经传入纤维中显示出最高的背根动作电位（DAP），并且不损害其以保留术后尿功能。因此，S1根的切除在降低FPR的踝痉挛中起关键作用。但是，在极少数情况下，即使是S1根，在阴部神经的传入纤维中也可能显示高DAP。

目的

本简短的技术说明旨在描述如何处理在阴部神经传入纤维中具有相对较高DAP的S1根。

方法

在此过程中，将S1根分为几个rootlet，然后测试每个rootlet的阴部映射。一连串的电刺激传递到标准FPR中的每个根。如果电刺激后的肌电图（EMG）异常高度异常，而阴部测绘未显示DAP或相对较低，则切除小根。相反，即使根部显示高度异常的EMG发现，如果映射显示相对较高的DAP，也可以保留它。

结论

S1阴部测绘与EMG检查结果相结合，可实现令人满意的踝部痉挛减少，同时保留泌尿功能。