Effects of Laser Therapy (680 nm) on Recovery of the Sciatic Nerve in Rabbits

摘要

Peripheral nerve injuries are common, and there is no easily available formula for successful treatment.Incomplete injuries are most frequent. After complete axonal transection, the neuron undergoes a number ofdegenerative processes, followed by attempts at regeneration. Unfortunately, results of nerve repair to date havebeen no better than fair. Many evidence lines have shown that peripheral nerves regeneration may be acceleratedby physical agents. Laser irradiation is one of the therapeutic methods for the recovery of degenerated peripheralnerves. The objective of this study was to investigate whether laser therapy (680 nm) could stimulate the healingprocess in the sciatic nerve regeneration in rabbits submitted to complete transection through histologicalanalysis. Twenty adult white New Zealand male rabbits were used, where the injury of the type neurotmesis ofthe right sciatic nerve under general anesthesia (intramuscular ketamine/xylazine) was approximated usingprolene 6-0. The rabbits were randomly distributed in 2 groups with 10 rabbits each. In group I, Arsenate ofGallium Laser with the extension of wave of 680 nm, 10 mW power with 1.0 J/cm2 irradiation with 10 secondsfor each Cm2, in the pulsed form. The laser therapy in group I was initiated on the post-surgical first day, whereall the rabbits with application once a day for 14 days or 10 minutes each rabbit. Rabbits in group II not hadgiven treatment (control group). The samples of transected nerves were collected and prepared of histologicalanalysis on the 30 days. The histological aspect showed that in the injury site, blood vessels were moreprevalent and thicker for group I than group II. Thick fibers with very thin myelin sheaths were prevalent in theinjury site in both groups. Schwann cells with reactive appearance nuclei, characteristic of synthesis activity, aswell as typical images of axonal sprouting were more prevalent on group I, while Wallerian degeneration wasmore evident on group II. Small-gauge fibers and thin myelin sheaths were prevalent, although thick fibers andthick myelin sheaths were also frequent on group II next to a large number of Schwann cells with reactiveappearancenucleus and images of axonal sprouting. In this site, Wallerian degeneration was not so evident forgroup I. This study suggests that postoperative laser irradiation (680 nm) was able to accelerate and potentializethe peripheral nerve regeneration process of rabbits.