Dermal Sensory Interfaces for Providing Feedback to Amputees
Alixandra L. VanBelkum, BA1, Ian C. Sando, MD1, Gregory J. Gerling, PhD2, Daniel C. Ursu, MS1, Yaxi Hu, MD3, Elizabeth A. Mays, BSE1, Jana D. Moon, BS1, Paul S. Cederna, MD1, Melanie G. Urbanchek, PhD1.
1University of Michigan, Department of Surgery, Section of Plastic Surgery, Ann Arbor, MI, USA, 2University of Virginia, Department of Systems and Information Engineering, Charlottesville, VA, USA, 3University Medical Center Groningen, Department of Plastic Surgery, Groningen, Netherlands.
PURPOSE: We developed a Dermal Sensory Interface (DSI) with the ultimate goal of providing amputees with meaningful sensory feedback through the residual nerve. Our purpose was to: a) determine predictability of afferent nerve action potentials evoked by electrical stimuli delivered to DSIs; and b) verify that sensory peripheral nerves neurotize DSIs implanted subcutaneously without forming neuromas.
METHODS: Rat hind limbs were assigned into one group: a) control full-thickness skin (n=10), b) control de-epithelialized skin (n=10), c) control sural nerve (n=10), and d) DSI (n=10). Each DSI was constructed by surrounding the residual sural (sensory) nerve with an autologous de-epithelialized glabrous skin graft. Following two months’ convalescence, patterned electrical stimuli were applied, and evoked responses were recorded at the sural nerve.
RESULTS: All DSIs showed healthy revascularization. Over 96% of pulses delivered to DSIs at 100 A above absolute current threshold elicited graded compound sensory nerve action potentials (CSNAPs) at frequencies ≤100Hz (Fig 1). Three-dimensional microscopy visualized robust reinnervation of DSIs originating from transected sural nerve fibers without formation of neuroma (Fig 2).
CONCLUSION: Electrical stimuli of varying frequency and amplitude reliably evoke graded sensory nerve feedback from DSIs and sensory fibers regenerate throughout DSI constructs without signs of neuroma.
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