Objective: This study seeks to determine, through functional gait assessment in different irradiation sites, the influence of a low-intensity GaAsAl laser beam on an injury caused by crushing the peroneal nerve in rats. Methods: 53 rats were used, which were divided into six groups: normal, injured and untreated, injured and treated using placebo, injured and treated in the bone marrow, injured and treated in the nerve, and injured and treated in both (nerve and bone marrow). The peroneal nerve was crushed using a pair of tweezers, and subsequently treated with laser for 28 consecutive days. The functional gait evaluation analyzed the footprints, which were recorded with a video camera on an acrylic bridge in the preoperative period, and on postoperative days 14, 21 and 28, and assessed using PFI formula software. Results: In the functional gait evaluation, significant differences were found only on postoperative day 14. Conclusion: Based on the functional gait evaluation, low-intensity GaAsAl irradiation was able to accelerate and reinforce the process of peripheral nerve regeneration in rats on postoperative day 14, both in the bone marrow-and in the nerve-treated groups.Keywords: Nerve regeneration. Crush syndrome. Laser therapy. introductionSeveral authors investigate the influence of the various therapeutic treatments, in the regeneration of rat sciatic nerve, such as electrical stimulation, 1 therapeutic ultrasound 2 and low-intensity laser that has received more attention in the last decade.3 Low-intensity laser mechanisms are not fully understood, but some studies have attempted to explain the effects of their irradiation on biological tissue, 4,5 obtaining controversial considerations provided by different methodologies, such as dosage, wavelength, continuous or pulsed current, 4-6 irradiation site and treatment duration. The recovery of peripheral nerve injuries is studied mainly through electrophysiological and hystomorphometric parameters, which, although useful, do not keep track of functional recovery during treatment, which is important to quantify in a non invasive manner, and to reproduce the methods for a functional evaluation of nerve regeneration. 7 Therefore it might be better to use functional gait assessment rather than simply the electrophysiological and morphometric bases for axon growth and muscular innervation, provided the main interest of the survey is functional outcome. 8 The gait analysis has proved to be a safe method of functional assessment, monitoring the process from nerve lesion through to repair, 7,9 having a strong correlation with morphological evaluation. 1,9 Low-intensity laser is usually irradiated at the site of the crush injury. Rochkind et al. 4 used laser irradiation at the root of the spinal cord, in the branch that corresponds to the sciatic nerve of rats (L2), and were able to observe an increase in neuron metabolism and an improvement in myelin production that serves to accelerate injured nerve regeneration. Anders et al. 3 explained that the effec...

OBJECTIVE: The influence of dose of low power lasertherapy (AsGaAl, 830 nm) on the regeneration of the fibular nerve of rats after a crush injury was evaluated by means of the functional gait analysis and histomorphometric parameters. METHODS: Controlled crush injury of the right common fibular nerve, immediately followed by increasing doses (G1: no irradiation; G2: simulated; G3: 5 J/cm2; G4: 10 J/cm2; G5: 20 J/cm2) laser irradiation directly on the lesion site for 21 consecutive days. Functional gait analysis was carried out at weekly intervals by measuring the peroneal/fibular functional index (PFI). The animals were killed on the 21st postoperative day for removal of the fibular nerve, which was prepared for the histomorphometric analysis. RESULTS: The PFI progressively increased during the observation period in all groups, without significant differences between them (p>0.05). The transverse nerve area was significantly wider in group 2 than in groups 3 and 4, while fiber density was significantly greater in group 4 than in all remaining groups. CONCLUSION: The low power AsGaAl laser irradiation did not accelerate nerve recovery with any of the doses used. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment.

OBJECTIVE: To investigate the influence of low intensity laser irradiation on the regeneration of the fibular nerve of rats after crush injury. METHODS: Twenty-five rats were used, divided into three groups: 1) intact nerve, no treatment; 2) crushed nerve, no treatment; 3) crush injury, laser irradiation applied on the medullary region corresponding to the roots of the sciatic nerve and subsequently on the course of the damaged nerve. Laser irradiation was carried out for 14 consecutive days. RESULTS: Animals were evaluated by functional gait analysis with the peroneal functional index and by histomorphometric analysis using the total number of myelinated nerve fibers and their density, total number of Schwann cells, total number of blood vessels and the occupied area, minimum diameter of the fiber diameter and G-quotient. CONCLUSION: According to the statistical analysis there was no significant difference among groups and the authors conclude that low intensity laser irradiation has little or no influence on nerve regeneration and functional recovery. Laboratory investigation.