Somatic sensibility to mechanical vibrations on the forearms of seniors and transradial amputees

Abstract

BackgroundThe majority of prostheses and orthoses depend on visual feedback for effective use. They do not employ cutaneous and proprioceptive sensibility to improve their control. The objective of this study was to analyze the effects of changes in stimulation intensity and area as frequency changes on somatic sensation in the elderly and transradial amputees. MethodTo measure change of residual somatic sensibility, we set up a mechanical vibration system utilizing eight-channel stimulators with a frequency range from 37Hz to 223Hz, a reception system for measuring and monitoring, and a subjective response evaluation with a 1–10 scale. Eighty subjects (30 young, 30 elderly, and 20 amputees) were involved and the effect of random mechanical stimulation on 25% of the proximal forearm's area was measured. FindingsThe results showed that the amputee group's lateral area sensitivity was relatively higher than its medial area sensitivity, like those of the young group, but the elderly group's sensitivity was the highest in the sites between the lateral and the medial areas. For the stimulation intensity, while the young females and the amputee females showed responses proportionate to the intensity of stimulation, all groups' males and elderly females underwent saturation at certain frequencies. InterpretationThese studies will be helpful in the design of advanced prostheses and orthoses which include somatic biofeedback information to overcome the current limitations of existing assistive devices.