A clinical study on serum prostaglandin E2 with low-level laser therapy.

Methods: The subjects of this investigation consisted of 83 female patients that were treated in this department during the 2-year period from January 1999 to December 2002. Laser irradiation was applied for 3 min either every day or every other day for a total of 10 times. A diode semi-conductor laser with a wavelength of 830 nm and a photointensity of 1 W was used. Evaluations were performed before and after the series of 10 exposures to laser irradiation. The evaluation included the measurement of pain using the visual analog scale (VAS) and serum prostaglandin E(2) (pg/mL) measured by RIA-PEG.

Results: The analgesic effects were observed in 67 of 83 cases, or 80.7%. The VAS scores for the effective cases decreased after the irradiation series from 8.5 +/- 0.2, to 2.8 +/- 0.2 ( p < 0.001). The post-irradiation PGE(2) levels were lower than the pre-irradiation PGE(2) levels in the effective cases, which were 5.8 +/- 0.3 and 7.1 +/- 0.4 pg/mL, respectively ( p < 0.05). The postirradiation PGE(2) levels for the effective cases were lower than those for the ineffective cases, which were 5.8 +/- 0.3 and 7.3 +/- 0.9 pg/mL, respectively ( p < 0.05).

Conclusions: Based on the above findings, the analgesic effects of LLLT were found to be valid. The serum PGE(2) levels are therefore considered to directly reflect nociceptive pain.