Intrafascicular peripheral nerve stimulation produces fine functional hand movements in primates

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Technology

Background:

• Restoring dexterous hand control is a critical unmet need for individuals with paralysis.
• Current stimulation methods (surface, intramuscular) offer limited finger control, insufficient force, and require many electrodes.

Purpose of the Study:

• To investigate the efficacy of intrafascicular peripheral electrodes for restoring functional hand movements.
• To assess the ability of these electrodes to generate functional grasps and sustained forces.

Main Methods:

• Designed and implanted intrafascicular electrodes targeting motor fibers of the median and radial nerves in three monkeys.
• Evaluated selective activation of extrinsic and intrinsic hand muscles.
• Tested functional grip generation, hand opening, and sustained force production for up to 2 months.
• Extended findings to a monkey with transient hand paralysis, using intracortical signals for stimulation control.

Main Results:

• Intrafascicular electrodes reliably activated hand muscles, producing multiple functional grips and hand opening.
• Sustained muscle contraction forces were achieved for up to 2 months.
• A monkey with transient paralysis successfully performed a functional grasping task using intracortical signal-controlled stimulation.
• Demonstrated that two intrafascicular electrodes can generate a diverse range of dexterous hand movements.

Conclusions:

• Intrafascicular peripheral electrodes offer a promising approach for restoring hand function in paralysis.
• This technology enables functional grasps and sustained forces, surpassing limitations of current methods.
• The findings have significant implications for the clinical application of neural interfaces for hand restoration.