Dose Thresholds and Effect Mechanisms for Pain Management with LASER Phototherapy

Arguably, the two most important aspects regarding laser phototherapy for pain management are those of effect mechanism (to determine the most appropriate application) and of dosing parameters. Herein is summarised the outcomes of more than 15 years of the author's research to date, to clarify some of these factors. Initial investigations demonstrated that the central descending inhibitory (endogenous opioid) system was involved in the effect mechanism of phototherapy and that doses below 5.1/cm(2) in the wavelengths tested, had the best effects in a chronic pain clinical model. Subsequent research using a non-invasive clinical model in lateral epicondylalgia has established that the descending inhibitory system is not the sole likely origin of the treatment response; or, if it is, it plays this role selectively for only some combinations of wavelength, dose and power output. Repeated low doses of laser (at some wavelengths) are sufficient to stimulate physiological responses and reduce pain in subjects with lateral epicondylalgia. It is clear further information is required for dosing and dose threshold factors of laser phototherapy for clinical pain management.