Optically mediated nerve stimulation: Identification of injury thresholds
Article first published online: 20 JUL 2007
Copyright © 2007 Wiley-Liss, Inc.
Lasers in Surgery and Medicine
Volume 39, Issue 6, pages 513–526, July 2007
How to Cite
Wells, J. D., Thomsen, S., Whitaker, P., Jansen, E. D., Kao, C. C., Konrad, P. E. and Mahadevan-Jansen, A. (2007), Optically mediated nerve stimulation: Identification of injury thresholds. Lasers Surg. Med., 39: 513–526. doi: 10.1002/lsm.20522
- Issue published online: 20 JUL 2007
- Article first published online: 20 JUL 2007
- Manuscript Accepted: 22 MAY 2007
- MFEL/AFOSR program. Grant Number: FA9550-04-1-0045
- National Institutes of Health support. Grant Number: R01 NS052407-01
- laser irradiation;
- histological analysis;
- optical nerve stimulation;
- peripheral nerve;
- thermal damage
Background and Objective
Transient optical nerve stimulation is a promising new non-contact, spatially precise, artifact-free neural excitation technique useful in research and clinical settings. This study evaluates safety of this pulsed infrared laser technique by histopathologic examination of stimulated peripheral nerves.
Study Design/Materials and Methods
Exposed rat sciatic nerves were functionally stimulated with the pulsed Holmium:YAG laser, previously validated as an effective tool for optical stimulation. Nerves were removed immediately and up to 2 weeks after stimulation and assessed histologically for thermal damage. Laser parameters studied include upper limits for radiant exposure, repetition rate, and duration of stimulation.
Radiant exposures with <1% probability of thermal tissue damage (0.66–0.70 J/cm2) are significantly greater than radiant exposures required for reliable stimulation (0.34–0.48 J/cm2). The upper limit for safe laser stimulation repetition rate occurs near 5 Hz. Maximum duration for constant low repetition rate stimulation (2 Hz) is ∼4 minutes with adequate tissue hydration.
Results confirm that optical stimulation has the potential to become a powerful non-contact clinical and research tool for brief nerve stimulation with low risk of nerve thermal damage. Lasers Surg. Med. 39:513–526, 2007. © 2007 Wiley-Liss, Inc.