title: Monochromatic infrared irradiation (890 nm): effect of a multisource array upon conduction in the human median nerve.
abstract: OBJECTIVE
  Antidromic conduction studies in the human median nerve were used to assess the neurophysiological effects of irradiation of the skin overlying the nerve using a novel treatment unit comprising a multisource monochromatic infrared diode array (Equilight, Denver, CO).
  
  
  METHODS
  Healthy human volunteers (n = 40) were recruited and randomly allocated to one of four groups: control, placebo, or one of two treatment groups (1.7 and 4.0 J/cm2). After baseline recordings of negative peak latency (NPL) were completed on the nondominant arm, subjects were treated according to group allocation. Recordings were subsequently repeated at 5-min intervals over a 45-min period.
  
  
  RESULTS
  Analysis of negative peak latency difference scores (ANOVA) demonstrated significant differences in NPL between groups and over time (p < 0.05). While in the control and placebo groups NPL values remained relatively stable, in the two treatment groups such values decreased marginally, with the greatest effects observed in the 4.0 J/cm2 group (e.g., at 5 min, differences in NPL [mean +/- SEM]: control group, 0.02+/-0.03 msec; treatment group 2, 4 J/cm2, -0.07+/-0.03 msec). Similar significant differences were observed in skin temperature; correlation analysis indicated a weak (but expected) positive linear relationship between skin temperature and nerve conduction velocity (r = 0.125).
  
  
  CONCLUSIONS
  These results suggest that irradiation at the parameters and under the conditions used here produce a direct neurophysiological effect. The magnitude of such effects are in keeping with previous findings using single source arrays at higher radiant exposures or thermal effects of the treatment unit.
authors.affiliation: Rehabilitation Sciences Research Group, University of Ulster at Jordanstown, Newtownabbey, Northern Ireland.
authors.forename: J G
authors.initials: JG
authors.lastname: Noble
authors.forename: A S
authors.initials: AS
authors.lastname: Lowe
authors.forename: G D
authors.initials: GD
authors.lastname: Baxter
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007259:Infrared Rays; D008297:Male; D008475:Median Nerve / Q000502:physiology / Q000528:radiation effects*; D009431:Neural Conduction / Q000502:physiology / Q000528:radiation effects*; D011336:Probability; D011829:Radiation Dosage; D011930:Reaction Time / Q000528:radiation effects; D012016:Reference Values; D012680:Sensitivity and Specificity