Voice-Controlled Dual-Site Functional Electrical Stimulation Enables Tenodesis Grasping

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Neuroscience

Background:

• High-level spinal cord injuries (SCIs) can impair hand function, limiting independence.
• The tenodesis grasp, relying on wrist extension for finger flexion, is unavailable to individuals lacking wrist control.
• Restoring grasp function is crucial for improving the quality of life for SCI patients.

Purpose of the Study:

• To develop and validate a voice-controlled functional electrical stimulation (FES) system to evoke a tenodesis grasp in individuals with SCI.
• To assess the system's efficacy in both healthy participants and a patient with C5 SCI.

Main Methods:

• A voice-controlled, dual-site FES system was designed to simultaneously stimulate wrist extensors and finger flexors.
• Hand kinematics were measured in healthy participants to validate grasp evocation.
• Functional testing was performed with a C5 SCI patient lacking hand and wrist strength.

Main Results:

• The FES system successfully evoked a tenodesis grasp in healthy participants, reducing finger-to-metacarpophalangeal joint distance from 70 mm to 45 mm.
• A C5 SCI participant was able to grasp and hold an eating utensil using the assistive system.
• The system demonstrated reliable grasp closure through electrical stimulation.

Conclusions:

• The developed voice-controlled FES system effectively restores tenodesis grasp function.
• This technology represents a significant advancement towards wearable assistive devices for C5 SCI patients.
• The system has the potential to significantly improve hand function and independence for individuals with high-level SCIs.