Effects of near-infrared irradiation to stellate ganglion in glossodynia

OBJECTIVE: This study was designed to assess the effect of stellate ganglion near-infrared irradiation (SGR) on glossodynia and the mechanism of action. STUDY DESIGN: Thirty-seven patients with glossodynia received SGR once weekly for 4 weeks. The response to treatment was evaluated on the basis of the change in pain intensity, assessed with a visual analogue scale (VAS) before and after 4 weeks of treatment. The temperature and blood flow of the tongue were also measured before and after first SGR. As control, eight healthy subjects were studied. RESULTS: Tongue pain as assessed by the VAS decreased in 28 of the 37 patients (75.7%). Mean pain intensity decreased significantly from 5.1 +/- 2.2 to 1.9 +/- 2.1 (P < 0.05). Tongue blood flow at rest in the patients with glossodynia [7.2 +/- 1.6 ml min(-1) (100 g)(-1)] was significantly lower than that in the healthy subjects [7.8 +/- 0.23 ml min(-1) (100 g)(-1)]. Five minutes after SGR, the temperature of the tongue rose 1.5 +/- 0.21degreesC, and blood flow increased to 8.5 +/- 1.2 ml min(-1) (100 g)(-1). Tongue blood flow (at rest) after 4 weeks of SGR had increased to 7.7 +/- 1.1 ml min(-1) (100 g)(-1). CONCLUSION: SGR is an effective treatment for glossodynia. The mechanism by which SGR improves symptoms associated with glossodynia is thought to be as follows: SGR inhibits abnormally increased sympathetic activity associated with glossodynia. This is followed by normalization of decreased tongue blood flow, thereby alleviating pain.