Effects of 830 nm continuous wave laser diode irradiation on median nerve function in normal subjects.

The presence, magnitude, and nature of the effect that low intensity laser irradiation has on nerve function, growth, and repair constitute a contentious area of research. We have addressed one aspect of this controversy by systematically examining the influence of 830 nm laser radiation on median nerve function. In particular, we investigated median nerve motor and sensory distal latencies, action potential amplitudes, action potential areas, and conduction velocities as well as dorsal hand skin temperatures in 33 normal subjects in a double-blinded, randomized controlled study. All subjects received identical treatment: 30 seconds of "irradiation" at 10 points over the course of the right median nerve (five sites on the forearm and five sites distal to the wrist crease) with either an active (1.2 J/point) or inactive (0 J/point) 40 mW 830 nm continuous wave IR laser diode. Latencies, conduction velocities, amplitudes, areas, and skin temperatures were collected bilaterally at a baseline immediately prior to irradiation and at intervals of 1, 5, 10, 15, 20, and 30 minutes following treatment. Analysis of the results reveals that motor and sensory distal latencies were decreased in the treated limbs of the laser-treated group relative to the control group by 3-4% (P < .016 and .046, respectively, rank sum test). No significant differences in these quantities were found between the limbs within either group. Similarly, no alterations of action potential amplitudes, action potential areas, forearm conduction velocities, or skin temperatures were detected within or between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Normal range of motion of the cervical spine: an initial goniometric study.

The purposes of this study were (1) to determine normal values for cervical active range of motion (AROM) obtained with a "cervical-range-of-motion" (CROM) instrument on healthy subjects whose ages spanned 9 decades, (2) to determine whether age and gender affect six cervical AROMs, and (3) to examine the intratester and intertester reliability of measurements obtained. Measurements were made on 337 subjects (171 females and 166 males) whose ages ranged from 11 to 97 years. Measurements were taken by five physical therapists with 7 to 30 years of clinical and teaching experience. Among male and female subjects of the same age, females had a greater AROM than did males for all AROMs except neck flexion. Among both males and females, each of the six cervical AROMs decreased significantly with age. From two pilot studies separate from the acquisition of the normal database, we determined our intratester and intertester reliabilities for making neck AROM measurements with the CROM instrument. We concluded that AROM measurements on the cervical spine with the CROM instrument demonstrated good intratester and intertester reliability, because the intraclass correlation coefficients were generally greater than .80.

Does low-intensity helium-neon laser irradiation alter sensory nerve active potentials or distal latencies?

The effect of 1 mW helium neon continuous-wave (0.633 microns) laser irradiation on superficial radical sensory and median sensory nerve function was examined in a double-blind, controlled study involving 40 volunteers. No differences in action potential amplitudes, distal latencies, or forearm skin temperatures were found between the treated and control groups either at the time of irradiation or at subsequent evaluations 15 and 30 minutes later. As a result, we are unable to confirm reports that low-energy lasers of this power and wavelength alter nerve function.

Does low-energy helium-neon laser irradiation alter "in vitro" replication of human fibroblasts?

Cultured human fibroblasts were treated in a controlled, randomized manner to assess the effect of low-energy (0.9 mW) helium-neon (HeNe) laser irradiation on cellular proliferation. Two trials were performed: one with fibroblasts in the third to fourth passage and the other with fibroblasts in the 13th to 14th passage. In each trial, separate plastic petri dishes were inoculated with the cells, maintained in a 5% CO2-95% air atmosphere, and nourished with HB 102 media. Treatment began 48 h after inoculation with daily 60-s irradiations of the "treated" cultures over a 5-d period. Control cultures underwent the same handling but were not irradiated. A significant stimulative, or inhibitive, effect on replication was not found in either trial.

Comparison of cold-quartz ultraviolet, low-energy laser, and occlusion in wound healing in a swine model.

A randomized, blind, controlled study used six pigs to examine the effectiveness of low-energy HeNe laser irradiation (632.8nm), cold-quartz UV (254nm), occlusion, and exposure in the treatment of full thickness skin wounds. Laser-treated wounds received a nominal dose of 54mW daily on a schedule of six days/week, UV-treated wounds were given two minimal erythemal dose treatments, twice daily, six days a week, and occluded wounds were checked and dressings replaced as needed twice daily, six days a week. All wounds were treated until clinically healed. Time to closure, wound strength, and bacterial colonization were monitored. There were no complications. Although the laser-treated wounds healed faster than the exposed-control wounds (20.3 +/- 0.9 days vs 21.1 +/- 2 days), only the occluded wounds healed significantly (p less than or equal to 0.05) faster than the controls (18 +/- 1.6 days vs 20.6 +/- 1.4 days). No statistically significant difference in bacterial colonization or wound strength was noted although the occlusion-treated wounds tended to be the strongest.