Functional and Neuroprotective Effects of Restoring Lower Limb Sensation after Diabetic Peripheral Neuropathy

Thus project addresses a gap in the available interventions for Veterans with Diabetic Peripheral Neuropathy (DPN), a large and growing chronic disease population within the VHA. Individuals with diabetes have a 10-times higher risk of amputations than the general population. We expect that discrete, meaningful sensations perceived to be arising from the

missing foot can be chronically elicited by multi-contact peripheral nerve cuff electrodes installed on the nerves in the thigh above the knee of Veterans with lower-limb loss due to DPN. We anticipate that these electrically elicited sensations can maintain the health and resiliency of the residual limb and provide meaningful feedback during daily activities. We will

rigorously document medical and medication history, and the interactions of the ongoing disease with the implanted components, and expect them to be well tolerated by volunteers with minimal clinical complications. Amputees pay less attention to their feet, are at risk for complications affecting the skin and

underlying tissues of their residual limb due to routine prosthetic socket use. We expect that eliciting sensation perceived as arising from the missing foot via neural stimulation will improve the health of the residual limb tissues of Veterans with limb loss due to DPN, and make them more resilient to potentially damaging loads. That is, circulation and residual limb tissue health

will improve, and the likelihood of developing complications will decrease with the restoration of appropriate sensation. Therefore, physiological measures of blood flow, temperature, transcutaneous oxygen and other indicators of underlying tissue health, as well as the and frequency and severity of phantom pain will change as a result of this unique intervention.

The sensations perceived as related to physical interactions of the prosthesis with the environment elicited with neural stimulation will also improve standing balance, walking mechanics, and overall confidence and activity levels of Veterans with lower-limb loss due to DPN. Standing balance and sway, and the ability to adapt to challenging or changing

environments, as well as subjective assessments of attention, balance confidence and fear of falling measured with and without sensory stimulation. We further anticipate that recipients of our Sensory Neuroprosthesis who have DPN will find it valuable in the home and community as evidenced by patterns of usage, total standing and walking time, and subjective ratings of

satisfaction and effort. We expect users to have increased mobility, and cope more effectively with disturbances to gait and balance. We will recruit and enroll a total of five new participants who will receive the surgically implanted systems, and act as their own historical (pre- and post-implantation) and concurrent

(with and without sensory stimulation) controls. The Sensory Neuroprosthesis previously developed by our group for traumatic trans-tibial amputees consisting of a wireless pressure sensitive insole and external neural stimulator will be adapted for the unique clinical needs of Veterans with DPN to deliver stimulation to the nerve via selected nerve electrode contacts at

the appropriate intensity corresponding to physical input to the foot. The successful completion of this project will yield the information required to define the requirements for the design of a self-contained system for Veterans with limb loss due to DPN that will be suitable for larger scale clinical trials or commercially-sponsored projects.