Efeitos da fotobiomodulação vascular na cefaleia tensional e dor orofacial em indivíduos com covid longa: ensaio clínico pragmático randomizado

Abstract

Orofacial pain and tension-type headache have been reported among individuals infected with COVID-19, including those who continue to experience these symptoms after recovery, in which case they are considered chronic. Pain management in such cases is commonly achieved through the use of analgesic and anti-inflammatory drugs. However, adjunctive therapies are available that can reduce medication intake and improve the quality of life of affected individuals, one of which is photobiomodulation (PBM). Laser therapy has shown successful results in controlling inflammation and pain; however, its optimal parameters and application protocols are not yet fully standardized. This study aimed to evaluate the effects of red and infrared laser photobiomodulation applied both locally and systemically. Individuals who had contracted COVID-19 and presented with tension-type headache and/or orofacial pain persisting for more than three months were conveniently recruited. Participants were randomized into four groups: (G1) infrared laser photobiomodulation applied locally to pain points; (G2) placebo photobiomodulation with local application; (G3) red laser photobiomodulation applied transcutaneously over the radial artery; and (G4) placebo photobiomodulation with transcutaneous application over the radial artery. All participants underwent eight treatment sessions over four weeks. Outcomes were assessed through blood lactate levels, the Brief Pain Inventory, Visual Analog Scale (VAS), and Headache Impact Test. Data analysis was performed using the Kruskal–Wallis and Wald multiple comparison tests for intergroup analysis, and the Friedman test followed by the paired Wilcoxon test for intragroup (time-point) comparisons. Associations between categorical variables and groups were assessed using the chi-square test, while associations between categorical variables in pre- and post-treatment moments were evaluated using the Mantel–Haenszel test stratified by group. The significance level was set at 5%. The results highlight the multifactorial complexity of tension-type headache and orofacial pain in post–SARS-CoV-2 infection patients, suggesting that COVID-19 may exacerbate parafunctional habits and preexisting musculoskeletal dysfunctions. Photobiomodulation, in both local and systemic modalities, demonstrated therapeutic potential in pain reduction, functional improvement, and metabolic modulation. Local application significantly alleviated pain, possibly due to mitochondrial activation, improved tissue perfusion, and inflammatory regulation, while systemic PBM contributed to enhanced quality of life, sleep, and general well-being. The reduction in lactate levels further supports the influence of PBM on bioenergetic and hemodynamic processes. These findings support PBM as a promising approach for pain management and functional recovery in patients with post–COVID-19 repercussions, while emphasizing the need for further controlled clinical trials employing standardized protocols and objective outcome measures.