Abstract
In this study we explored the possibility of suppressing pathological tremors using closed-loop functional electrical stimulation (FES) to activate the tremorogenic muscles out-of-phase. A displacement signal monitored with a transducer was filtered so as to be “tuned” to the tremor frequency at the wrist or elbow. The filtered signal was used to amplitude-modulate the electrical stimulation. The design process was based on measurements of the open-loop frequency response characteristics of the forearm and hand to stimulation of the elbow and wrist flexors and extensors in a number of subjects. These data allowed us to identify closed-loop configurations, which attenuated 2–5 Hz tremors substantially, while only minimally attenuating functional movements in the 0–1 Hz range. There was a fairly delicate balance between efficacy and the risk of instability. However, designs were identified that offered enough tremor suppression and adequate immunity to muscle/load variations for the technique to be considered seriously for clinical application.
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Prochazka, A., Elek, J. & Javidan, M. Attenuation of pathological tremors by functional electrical stimulation I: Method. Ann Biomed Eng 20, 205–224 (1992). https://doi.org/10.1007/BF02368521
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DOI: https://doi.org/10.1007/BF02368521