Natural Sensations Evoked in Distal Extremities Using Surface Electrical Stimulation

Abstract

Background:Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, surface electrical stimulation was evaluated as a method to non-invasively target a neural function, specifically natural sensation in the distal limbs.Method:Electrodes were placed over the median and ulnar nerves at the elbow and the common peroneal and lateral sural cutaneous nerves at the knee. Strength-duration curves for sensation were compared between nerves. The location, modality, and intensity of each sensation were also analyzed. In an effort to evoke natural sensations, several patterned waveforms were evaluated.Results:Distal sensation was obtained in all but one of the 48 nerves tested in able-bodied subjects and in the two nerves from subjects with an amputation. Increasing the pulse amplitude of the stimulus caused an increase in the area and magnitude of the sensation in a majority of subjects. A low frequency waveform evoked a tapping or tapping-like sensation in 29 out of the 31 able-bodied subjects and a sensation that could be considered natural in two subjects with an amputation. This waveform performed better than other patterned waveforms that had proven effective during implanted extra-neural stimulation.Conclusion:Surface electrical stimulation has the potential to be a powerful, non-invasive tool for activation of the nervous system. These results suggest that a tapping sensation in the distal extremity can be evoked in most able-bodied individuals and that targeting the nerve trunk from the surface is a valid method to evoke sensation in the phantom limb of individuals with an amputation for short term applications.

A Psychometric Platform to Collect Somatosensory Sensations for Neuroprosthetic Use

“…Somatosensory neuroprostheses are highly innovative devices (1). Several research groups have investigated the ability to restore sensory feedback in patients with upper or lower limb amputation, tetraplegia, or paraplegia using invasive (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) and non-invasive (15)(16)(17)(18)(19) interfaces with the peripheral (PNS) and the central nervous systems (CNS) (Figure 1). The main aim of these FIGURE 1 | Neuroprosthetic applications.…”

Iatrogenic median nerve injury as a result of venous cut down procedure: A rare case report

“…It has been suggested in literature that when the nerve trunk is targeted, muscle contractions and/or sensations can be produced in distal locations based on the innervation pattern of the nerve. As a result, stimulation of the median nerve at the elbow should produce muscle activation and/or sensation in the hand [ 16 , 17 ]. Hence, this patient was considered for surface electrical stimulation with the intended benefit of enhanced recovery.…”

Augmented Transcutaneous Stimulation Using an Injectable Electrode

“…A capture ratio (Gan and Prochazka, 2010) of INerve/ITES was calculated to estimate the efficiency of the transcutaneous current delivery to current arriving at the modeled deep nerve and reported as 'efficiency' (%). Lastly, surface electrode current density was used as a proxy for off-target cutaneous fiber activation (Slopsema et al, 2018) and INerve was used as a proxy for on-target neural fiber activation. Model geometry was set to replicate the parameters of a 50-60 kg domestic swine's lower abdomen, on which the model was validated, and is similar to human tissue thicknesses at the neck.…”

“…To investigate the effects of TES electrode size, edge-to-edge distance between the two surface electrodes was kept constant at 2 cm while the side length of the square surface electrodes was varied from 1 to 7 cm in the FEM model. The ratio of nerve current to surface electrode current density was plotted as a proxy for on-target nerve recruitment to off-target cutaneous fiber recruitment (Slopsema et al, 2018) in Fig. 5 (c), with the hypothesis that lower surface current densities generated by larger TES patches would reduce off-target cutaneous activation.…”