Residual function in peripheral nerve stumps of amputees: implications for neural control of artificial limbs1☆
Received 20 August 2003; accepted 2 February 2004.
Abstract
Purpose
It is not known whether motor and sensory pathways associated with a missing or denervated limb remain functionally intact over periods of many months or years after amputation or chronic peripheral nerve transection injury. We examined the extent to which activity on chronically severed motor nerve fibers could be controlled by human amputees and whether distally referred tactile and proprioceptive sensations could be induced by stimulation of sensory axons in the nerve stumps.
Methods
Amputees undergoing elective stump procedures were invited to participate in this study. Longitudinal intrafascicular electrodes were threaded percutaneously and implanted in severed nerves of human amputees. The electrodes were interfaced to an amplifier and stimulator system controlled by a laptop computer. Electrophysiologic tests were conducted for 2 consecutive days after recovery from the surgery.
Results
It was possible to record volitional motor nerve activity uniquely associated with missing limb movements. Electrical stimulation through the implanted electrodes elicited discrete, unitary, graded sensations of touch, joint movement, and position, referring to the missing limb.
Conclusions
These findings indicate that both central and peripheral motor and somatosensory pathways retain significant residual connectivity and function for many years after limb amputation. This implies that peripheral nerve interfaces could be used to provide amputees with prosthetic limbs that have more natural feel and control than is possible with current myoelectric and body-powered control systems.
aDepartment of Bioengineering, University of Utah, Salt Lake City, UT, USA
bDepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA
Reprint requests: Ken Horch, PhD, Department of Bioengineering, 50 S. Central Campus Dr, Room 2480, University of Utah, Salt Lake City, UT 84112 USA
☆ Supported by a grant from the National Institute of Neurological and Communicative Disorders and Stroke of the National Institutes of Health.
1 No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
ABSTRACT