Abstract: Dermal-Based Peripheral Nerve Interface for Transduction of Sensory Feedback (Plastic Surgery 2015)

Saturday, October 17, 2015: 8:00 AM

Ian C Sando, MD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Gregory J Gerling, PhD , Systems and Information Engineerig, University of Virginia, Charlottesville, VA

Daniel C Ursu, MS , Plastic Surgery, University of Michigan, Ann Arbor, MI

Kristoffer B Sugg, MD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Yaxi Hu, BS , Plastic Surgery, University Medical Center Groningen, Groningen, Netherlands

Steven C Haase, MD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Nicholas B Langhals, PhD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Paul S Cederna, MD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Melanie G. Urbanchek, PhD , Plastic Surgery, University of Michigan, Ann Arbor, MI

Presentation PDF file

PURPOSE: We developed a Dermal-based Sensory Regenerative Peripheral Nerve Interface (DSRPNI) with the long-range goal of providing high fidelity perception of somatosensory feedback from prosthetic limbs. DSRPNI units consist of small de-epithelialized skin grafts placed subcutaneously that are reinnervated by residual sensory peripheral nerves. Patterned electrical stimuli is applied to the DSRPNI to excite native mechanoreceptors within the DSRPNI sending action potentials along the residual sensory nerve to the somatosensory cortex for tactile perception. Our immediate purpose is to establish the predictability between graded electrical stimulation and evoked somatosensory feedback signaling in DSRPNI and control skin conditions.

METHODS: Using a rat model, de-epithelialized skin grafts were secured around the proximal end of the transected sural nerve in a submuscular pocket; these DSRPNI were allowed two months for reinnervation (Fig 1). We compared electrophysiological signals recorded at the proximal sural nerve in response to electrical stimulation on DSRPNI units (n=10), native full-thickness skin (n=10), and native de-epithelialized skin (n=10). Measurements included threshold stimulation current to evoke compound sensory nerve action potentials (CSNAPs), percent CSNAP elicitation (signal transduction sensitivity), and sural nerve potential in response to graded stimulation current.

RESULTS: Electrical stimulation of DSRPNI units reliably elicited CSNAPs. Stimulation current thresholds to evoke CSNAPs for DSRPNI units (465 ± 110 mA) were similar to those for full thickness skin (600 ± 281 mA, p = 0.17) and de-epithelialized skin (594 ± 186 mA, p = 0.8). Over 96% of pulses delivered to DSRPNI units elicited CSNAPs at frequencies less than or equal to 100Hz. CSNAP potential increased in a similar fashion for DSRPNI units, full-thickness skin, and de-epithelialized skin with increased stimulation current (Fig. 2). Histomorphometric analysis of DSRPNI tissue revealed healthy dermis with minimal inflammation and no evidence of neuroma.

CONCLUSIONS: Stimulation thresholds to evoke CSNAPs were similar between DSRPNI units and native skin. Varying the stimulation current applied to DSRPNI units produced differential CSNAP potentials characteristic of native afferent signaling amplitudes. These findings suggest that highly selective patterned electrical stimulation can be successfully transduced across DSRPNI units to produce graded sensory feedback.

LEGEND:

Figure 1. DSRPNI unit in vivo two months after fabrication.

Figure 2. Mean +/- SEM peak-to-peak sural nerve CSNAP amplitude (µV) in response to incremental increase in stimulation current (µA) above threshold.

27417 Dermal-Based Peripheral Nerve Interface for Transduction of Sensory Feedback