title: A new device concept for directly modulating spinal cord pathways: initial in vivo experimental results.
abstract: We describe a novel spinal cord (SC) stimulator that is designed to overcome a major shortcoming of existing stimulator devices: their restricted capacity to selectively activate targeted axons within the dorsal columns. This device overcomes that limitation by delivering electrical stimuli directly to the pial surface of the SC. Our goal in testing this device was to measure its ability to physiologically activate the SC and examine its capacity to modulate somatosensory evoked potentials (SSEPs) triggered by peripheral stimulation. In this acute study on adult sheep (n = 7), local field potentials were recorded from a grid placed in the subdural space of the right hemisphere during electrical stimulation of the left tibial nerve and the spinal cord. Large amplitude SSEPs (>200 µV) in response to SC stimulation were consistently obtained at stimulation strengths well below the thresholds inducing neural injury. Moreover, stimulation of the dorsal columns with signals employed routinely by devices in standard clinical use, e.g., 50 Hz, 0.2 ms pulse width, produced long-lasting changes (>4.5 h) in the SSEP patterns produced by subsequent tibial nerve stimulation. The results of these acute experiments demonstrate that this device can be safely secured to the SC surface and effectively activate somatosensory pathways.
authors.affiliation: Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Flouty
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oya
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kawasaki
authors.forename: Saul
authors.initials: S
authors.lastname: Wilson
authors.forename: Chandan G
authors.initials: CG
authors.lastname: Reddy
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Jeffery
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Brennan
authors.forename: Katherine N
authors.initials: KN
authors.lastname: Gibson-Corley
authors.forename: Marcel
authors.initials: M
authors.lastname: Utz
authors.forename: George T
authors.initials: GT
authors.lastname: Gillies
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Howard
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D012756:Sheep; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D062187:Spinal Cord Stimulation / Q000295:instrumentation*