EFFECT OF LOW-INTENSITY LASER (830 NM) IRRADIATION ON SKIN TEMPERATURE AND ANTIDROMIC CONDUCTION LATENCIES IN THE HUMAN MEDIAN NERVE - RELEVANCE OF RADIANT EXPOSURE

The effects of low intensity near-infrared laser radiation (830 nm; 1. 5-12 J/cm(2); continuous wave) on peripheral neurophysiology and skin temperature were investigated using antidromic conduction studies in t he human median nerve in vivo. Healthy human volunteers (n = 80) were recruited and randomly allocated to one of two control (n = 30) or fiv e laser groups (1.5, 3.0, 6.0, 9.0, and 12 J/cm(2) n = 10 per group). Analysis of variance (ANOVA) in negative peak latency difference score s (NPLDs) and skin temperature over a 20 min period post-irradiation d emonstrated a significant decrease in skin temperature following irrad iation at the lowest radiant exposure (1.5 J/cm(2)) coupled with a sig nificant increase in NPLDs (P < 0.05). While no such (significant) cha nges were found in the other laser groups, it was found that observed changes (increases and decreases) in NPLDs were inversely related to c hanges in skin temperature. These findings demonstrate measurable peri pheral neurophysiological effects of laser radiation concomitant with changes in skin temperature; however, further studies are indicated to establish the precise relationship between the observed effects on sk in temperature and nerve conduction. (C) 1994 Wiley-Liss, Inc.