This first in a series of studies investigates histochemical arnd biochemical changes in rat saphenous nerve Na-K-ATPase activity following irradiation by the 830 nm, 60 mW continuous wave beam of the gallium aluminium arsenide (GaAlAs) diode laser, Six seconds of GaAlAs radiation noticeably increased demonstrable Na-K-ATPase activity. 15 s irradiation elicited the peak of activity, 30 s irradiation showed a decrease in the raised activity, and an irradiation time dependent inhibition of activity was noted after laser irradiation of 60 s and 120 s. Biochemical results, obtained by measuring the Na-K-ATPase activity through measurement of the release of inorganic phosphate, closely paralleled those results revealed by histochemical analysis. It is suggested that changes of Na-K-ATPnse activity in LLLT-treated peripheral neural tissue ate associated with the pain attenuation process.
Post herpetic neuralgia can be an extremely painful condition which in many cases proves resistant to all the accepted forms of treatment. It is frequently most severe in the elderly and may persist for years with no predictable course. This trial was designed as - double blind assessment of the efficacy of low level laser therapy in the relief of the pain of post herpetic neuralgia with patients acting as their own controls. Admission to the trial was limited to patients with established post herpetic neuralgia of at least six months duration and who had shown little or no response to conventional methods of treatment. Measurements of pain intensity and distribution were noted over a period of eight treatments in two groups of patients each of which received four consecutive laser treatments. The results demonstrate a significant reduction in both pain intensity and distribution following a course of low level laser therapy.