Photobiomodulation: Implications for Anesthesia and Pain Relief.

OBJECTIVE This review examines the evidence of neural inhibition as a mechanism underlying pain relief and anesthetic effect of photobiomodulation (PBM). BACKGROUND PBM for pain relief has also been used for more than 30 years; however, the mechanism of its effectiveness has not been well understood. METHODS We review electrophysiological studies in humans and animal models and cell culture studies to examine neural responses to PBM. RESULTS Evidence shows that PBM can inhibit nerve function in vivo, in situ, ex vivo, and in culture. Animal studies using noxious stimuli indicate nociceptor-specific inhibition with other studies providing direct evidence of local conduction block, leading to inhibited translation of pain centrally. Evidence of PBM-disrupted neuronal physiology affecting axonal flow, cytoskeleton organization, and decreased ATP is also presented. PBM changes are reversible with no side effects or nerve damage. CONCLUSIONS This review provides strong evidence in neuroscience identifying inhibition of neural function as a mechanism for the clinical application of PBM in pain and anesthesia.