title: Infrared neural stimulation of human spinal nerve roots in vivo.
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 ([Formula: see text]) 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 [Formula: see text]. 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 [Formula: see text] and a [Formula: see text] 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.
authors.affiliation: Vanderbilt University , Department of Biomedical Engineering, 5824 Stevenson Center, Station B, Box 351631 Nashville, Tennessee 37235-1631, United States.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Cayce
authors.affiliation: Lockheed Martin , 22121 20th Avenue SE, Bothell, Washington 98021, United States.
authors.forename: Jonathon D
authors.initials: JD
authors.lastname: Wells
authors.affiliation: Vanderbilt University , Department of Biomedical Engineering, 5824 Stevenson Center, Station B, Box 351631 Nashville, Tennessee 37235-1631, United States.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Malphrus
authors.affiliation: Vanderbilt University , Department of Neurological Surgery, 1161 21st Avenue, Nashville, Tennessee 37232-2380, United States.
authors.forename: Chris
authors.initials: C
authors.lastname: Kao
authors.affiliation: University of Texas , Department of Biomedical Engineering, Austin, Texas, and 500 Discovery View Drive, Sequim, Washington 98382, United States.
authors.forename: Sharon
authors.initials: S
authors.lastname: Thomsen
authors.affiliation: Vanderbilt University , Department of Neurological Surgery, 1161 21st Avenue, Nashville, Tennessee 37232-2380, United States.
authors.forename: Noel B
authors.initials: NB
authors.lastname: Tulipan
authors.affiliation: 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.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Konrad
authors.affiliation: 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.
authors.forename: E Duco
authors.initials: ED
authors.lastname: Jansen
authors.affiliation: 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.
authors.forename: Anita
authors.initials: A
authors.lastname: Mahadevan-Jansen
keywords: electromyography; infrared neural stimulation; neurophotonics; optics; spinal nerve roots