Functional and Neuroprotective Effects of Restoring Lower Limb Sensation After Diabetic Peripheral Neuropathy
The study aims to apply implanted electrical stimulation to the residual nerves in Veterans who have lost lower limbs due to diabetic peripheral neuropathy. The goal would be to provide sensation to the missing limb to improve standing, walking and balance, and improve the health of the residual limb.
|Condition or Disease
The goal of this project is to enhance the mobility and daily function of Veterans who have lost a lower limb due to diabetic peripheral neuropathy by providing feedback of foot-floor interactions via a Sensory Neuroprosthesis employing neural stimulation. In parallel, the investigators aim to assess the potential of this intervention to impact reports of phantom pain and improve the health and viability of the tissue of the residual limb in all recipients of the system regardless of the etiology of their limb loss.
Electrodes are surgically implanted on one to four nerves of the residual limb. An external stimulation device will send pulses to the electrodes. The participant will be asked what they feel, and to draw the location of any perceived sensation on schematic maps. A sensorized prosthesis will be worn and stimulation will be administered while the participant is engaging in various functional tasks, such as standing, walking or climbing stairs or with visual or mental distractions. The investigators will apply standard subjective pain inventories and objective physiological measures of tissue health (e.g., temperature or oxygen perfusion) to document systemic changes related to context-appropriate electrically induced sensory input.
Arms and Interventions
|Experimental: Multi contact electrode implant
Ten subjects with lower limb amputation will receive implanted multicontact stimulating nerve cuff electrodes connected to temporary percutaneous leads. During experimental testing, a small amount of stimulation will be applied to the nerves through the contacts of the multichannel cuff electrode.
Device: Multi contact electrode implant
See arm description
Primary Outcome Measures
- Stimulation thresholds [9 months post implant]
Quantify the minimum stimulation required to evoke electrically induced sensations on the phantom limb.
- Functional Gait Assessment (FGA) [6 months post implant]
The Functional Gait Assessment is a 10 task test that measures postural stability. Each task is scored from 0 -3 with 0 indicating severe impairment in the task and 3 indicating normal ambulation. The scores are combined to give a total score. The maximum score is 30. A higher score indicates a better outcome.
Secondary Outcome Measures
- Neuropathic Pain Syndrome Inventory (NPSI) [4 years post implant]
The NPSI is comprised of five subscales, each representing different dimensions of neuropathic pain: burning spontaneous pain (burning), pressing spontaneous pain (pressing), paroxysmal pain (paroxysmal), evoked pain (evoked), and paresthesia/dysesthesia Each area subscale is scored between 0-10. The scores are not combined, but are able to report on different aspects of neuropathic pain. A higher score indicates a worse outcome.
Chronic, medically stable lower limb amputation due to diabetes or insensate foot due to DPN
Being ambulatory and ability to stand or walk with prosthesis or orthosis
Viable target nerves in the lower extremity as determined by standard-of-care clinical tests of nerve conduction, response to stimulation, sensory evoked potentials (SEP) and the like
Good skin integrity and personal hygiene
Absence of autoimmune deficiencies, seizure disorders or cardiac abnormalities contraindicating stimulation
Sufficient social support and personal ability to tolerate study procedures and comply with follow-up schedule
Active pressure ulcers or chronic skin ulcerations
Uncontrolled diabetes with HbA1c greater than or equal to 69 mmol/mol (8.5%)
Significant vascular disease
Significant history of poor wound healing
Significant history of uncontrolled infections
Significant pain in the foot, residual or phantom limb
Inability to speak English: The study design requires the subject to communicate and describe the elicited sensations in their lower limb
History of vestibular or movement disorders that would compromise balance or walking
Class II or III obesity (Body Mass Index > 35)
Uncontrolled depression, psychoses or cognitive impairments. Subjects with unstable mental illness or severe cognitive impairments may be unable to comply with a long term study schedule
Expectation that MRI will be required at any point for the duration of study or while percutaneous leads are in place. At this time MRI is contraindicated, subjects who require regular MRI should not enroll
Arthritis in the area of implant- Inflammation or stiffness in the area of implant could limit placement of the electrodes
Contacts and Locations
|Louis Stokes VA Medical Center, Cleveland, OH
Sponsors and Collaborators
- VA Office of Research and Development
- Principal Investigator: Ronald Triolo, PhD, Louis Stokes VA Medical Center, Cleveland, OH
Study Documents (Full-Text)None provided.