Avaliação do efeito da terapia com laser em baixa intensidade na atividade eletromiográfica e dor dos músculos mastigatórios em pacientes com cefaléia tensional

Abstract

Introduction: Among several disease conditions, tension headache is considered the third leading cause of disability in the world. Despite this, there is no consensus regarding the best treatment aimed at symptom control. Aims: To evaluate the effects of a protocol of low intensity laser therapy on the electromyographic activity of masticatory muscles and analgesia in patients with tension headache. Methods: Controlled, randomized, double-blind study. The sample consisted of 16 subjects with tension-type headache aged over 18 years. Subjects were randomly assigned to two groups: group 1 (active laser therapy) and group 2 (placebo laser therapy). Four laser therapy sessions were performed using a wavelength of 780 nm, energy density of 30 J / cm2, power of 60 mW, energy irradiated per point 2 J, totaling 16 J, lasting at each point of 20 seconds. Eight points were irradiated, being 2 points in the masseter muscle and 2 points in the anterior temporal muscle bilaterally. In the placebo group, the same points of the treatment group were irradiated, with the laser turned off, but with a sound beep similar to that of active therapy. The evaluations occurred before and after the intervention treatment and consisted of the following items: (1) electromyographic evaluation of the anterior temporal and masseter muscles bilaterally in situations of isotonia, isometry and rest; (2) pain evaluation using a 10-point visual analogue scale, whose scores ranged from 0 (no pain) to 10 (maximum pain). The results were tested for normality by the Shapiro-Wilk test. To compare the effects of laser therapy on electromyographic activity and analgesia between pre and post treatment groups, the unpaired t test was used. The effects of intragroup treatment were tested by paired t-test. The Statistical Package for Social Science (SPSS) 15.0 for Windows was used for all analyzes and a significance level of p <0.05 was adopted. Results: 16 women were recruited, with a mean age of 25.87 ± 7.14 (G1) and 25.12 ± 5.08 (G2). Significant decrease in pain was observed after 4 LBI therapy sessions in the treated group compared to the placebo group (p = 0.03). The electromyographic activity of the masseter and anterior temporal muscles remained unchanged after treatment in the groups tested. Conclusion: the results suggest that the protocol proposed in the present study has important clinical implications, since it was possible to prove that LBI therapy is an effective method for the control of pain in patients with tension headache, but it was not possible to identify changes in the electromyographic pattern Of these patients.