Efficacy of low-intensity laser therapy in trigeminal neuralgia: a systematic review

Introduction. Trigeminal neuralgia (TN) is a highly prevalent cranial neuropathy, recognized as one of the main chronic orofacial neuropathic pain conditions. Low-intensity laser therapy (LiLT) has been proposed as an analgesic alternative for treating neuropathic orofacial pain, although studies appear to be limited, without a consensus on dose. The study aim was to describe the efficacy of LiLT in TN treatment. Methods. Randomized clinical trials and controlled trials were identified in the PubMed, Scopus, Web of Science, and Sciencedirect databases for May 8, 2021. Three independent researchers reviewed titles and abstracts to determine their eligibility. Risk of bias and quality were assessed with the RoB 2 tool (Cochrane) and PEdro scale. decreased pain was considered the main outcome, and changes in the temporomandibular joint range of motion, strength, or disability were secondary outcomes. Results. The search yielded 1078 articles after eliminating duplicates, reduced to 13 when applying the selection criteria. Nine articles were ascribed a low risk of bias or remained without consensus (69.23%), obtaining an average score of 6 (PEdro). Thirteen trials showed pain reduction at the end of treatment and in follow-up, although with statistical significance for 8 articles only (p < 0.005). A decrease in drug consumption and an increase in serotonin levels were observed in experimental groups, which supports the systemic analgesic effects of local and remote LiLT. Conclusions. LiLT is effective in reducing pain in TN. However, more research is needed to establish a referential dose consensus for TN and other neuropathic pain conditions.