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Optically mediated nerve stimulation: Identification of injury thresholds
Author(s) -
Wells Jonathon D.,
Thomsen Sharon,
Whitaker Peter,
Jansen E. Duco,
Kao Chris C.,
Konrad Peter E.,
MahadevanJansen Anita
Publication year - 2007
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20522
Subject(s) - stimulation , laser , medicine , biomedical engineering , optics , physics
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. Results Radiant exposures with <1% probability of thermal tissue damage (0.66–0.70 J/cm 2 ) are significantly greater than radiant exposures required for reliable stimulation (0.34–0.48 J/cm 2 ). 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. Conclusion 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.