Photobiomodulation in the treatment of chronic non-specific neck pain. Randomized clinical trial

Introduction
Neck pain is defined as the presence of musculoskeletal pain in the posterior region of the neck, above the shoulders, or in the upper dorsal area. Physiotherapy aims to minimize pain, recover mobility, and strengthen muscles. For this, it uses several techniques, such as photobiomodulation, which can be achieved by light emitting diode (LED) therapy and low level laser therapy (LLLT). The objective of this study was to analyse the effect of the association of LED and LLLT in the treatment of chronic non-specific neck pain.

Methods
A quantitative, experimental, randomized study was performed. The sample was composed of 28 individuals, divided into a control group and an intervention group. Pre- and post-treatment visual analogue scale, Leeds Assessment of Neuropathic Symptoms and Signs, and the McGill Pain Questionnaire were used. Both groups were submitted to 6 sessions during 2 weeks, with a cluster apparatus, composed of an arrangement of 3 LEDs (590 nm, 1500 mW) and an LLLT (830 nm, 150 mW); the control group received placebo laser intervention. The application was punctual (1 minute per region), at the point of greatest pain, in the trapezius, scalene, and sternocleidomastoid muscles.

Results
In both cases, the pain reduction was significant (p < 0.05) for the 3 assessment instruments; however, the effect sizes for the visual analogue scale and the McGill Pain Questionnaire were higher in the intervention group.

Conclusions
The cluster used was effective in reducing pain in individuals with chronic non-specific neck pain.