Research Papers

Infrared neural stimulation of human spinal nerve roots in vivo

[+] Author Affiliations
Jonathan M. Cayce, Jonathan D. Malphrus

Vanderbilt University, Department of Biomedical Engineering, 5824 Stevenson Center, Station B, Box 351631 Nashville, Tennessee 37235-1631, United States

Jonathon D. Wells

Lockheed Martin, 22121 20th Avenue SE, Bothell, Washington 98021, United States

Chris Kao, Noel B. Tulipan

Vanderbilt University, Department of Neurological Surgery, 1161 21st Avenue, Nashville, Tennessee 37232-2380, United States

Sharon Thomsen

University of Texas, Department of Biomedical Engineering, Austin, Texas, and 500 Discovery View Drive, Sequim, Washington 98382, United States

Peter E. Konrad, E. Duco Jansen, Anita Mahadevan-Jansen

Vanderbilt University, Department of Biomedical Engineering, 5824 Stevenson Center, Station B, Box 351631 Nashville, Tennessee 37235-1631, United States

Vanderbilt University, Department of Neurological Surgery, 1161 21st Avenue, Nashville, Tennessee 37232-2380, United States

Neurophoton. 2(1), 015007 (Feb 23, 2015). doi:10.1117/1.NPh.2.1.015007
History: Received November 12, 2014; Accepted January 12, 2015
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Abstract.  Infrared neural stimulation (INS) is a neurostimulation modality that uses pulsed infrared light to evoke artifact-free, spatially precise neural activity with a noncontact interface; however, the technique has not been demonstrated in humans. The objective of this study is to demonstrate the safety and efficacy of INS in humans in vivo. The feasibility of INS in humans was assessed in patients (n=7) undergoing selective dorsal root rhizotomy, where hyperactive dorsal roots, identified for transection, were stimulated in vivo with INS on two to three sites per nerve with electromyogram recordings acquired throughout the stimulation. The stimulated dorsal root was removed and histology was performed to determine thermal damage thresholds of INS. Threshold activation of human dorsal rootlets occurred in 63% of nerves for radiant exposures between 0.53 and 1.23J/cm2. In all cases, only one or two monitored muscle groups were activated from INS stimulation of a hyperactive spinal root identified by electrical stimulation. Thermal damage was first noted at 1.09J/cm2 and a 21 safety ratio was identified. These findings demonstrate the success of INS as a fresh approach for activating human nerves in vivo and providing the necessary safety data needed to pursue clinically driven therapeutic and diagnostic applications of INS in humans.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Jonathan M. Cayce ; Jonathon D. Wells ; Jonathan D. Malphrus ; Chris Kao ; Sharon Thomsen, et al.
"Infrared neural stimulation of human spinal nerve roots in vivo", Neurophoton. 2(1), 015007 (Feb 23, 2015). ; http://dx.doi.org/10.1117/1.NPh.2.1.015007


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