Neuromodulation : journal of the International Neuromodulation Society
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The purpose of this paper is to discuss which nerve fibers in the various quadrants of the spinal cord are immediately activated under normal conditions of spinal cord stimulation, ie, at voltages within the therapeutic range. The conclusions are based on both empirical and computer modeling data. The recruitment of dorsal column (DC) fibers is most likely restricted to Aβ fibers with a diameter ≥ 10.7 μm in a 0.20-0.25 mm layer under the pia mater and fibers of 9.4-10.7 μm in an even smaller outer layer when a conventional SCS lead is used. ⋯ The latter are presumably of proprioceptive origin and responsible for segmental reflexes and uncomfortable sensations. Furthermore, it is shown to be unlikely that, apart from dorsal roots and a thin outer layer of the DCs, any other spinal structures are recruited when stimulation is applied in the dorsal epidural space. Finally, anodal excitation and anodal propagation block are unlikely to occur with SCS.
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In this paper we present an overview of current research into clinical and therapeutic applications of electrical neuromuscular stimulation (NMS). As this is now such a huge subject we have focused our attention on the therapeutic rather than orthotic uses of stimulation and limited the field almost exclusively to upper limb applications in hemiplegia. ⋯ We discuss recent research aimed at resolving these issues and based on this we make some suggestions for future research. To resolve these issues we propose: 1) neurophysiologic research into the mechanism through which NMS interacts with the nervous system; 2) large multicenter randomized controlled trials using rigorous methodology that compare different applications of NMs; 3) continued technical development that is closely linked to clinical applications.