Use of Laser, 670 nm, in Painful Episodes of Rats Submitted to Experimental Model of Sciatica

Sciatica is caused by the sciatic nerve compression in some point of its course, and its treatment consists of solving the nervous compression cause, either by surgical or conservative treatment. Some physiotherapeutic resources act basically in the reduction of the symptoms caused by this disturbance. The aim of this study was to verify the effectiveness of the laser 670 nm, in two different energy densities, in the pain reduction, in rats submitted to a sciatica experimental model. Eighteen rats, divided in 3 groups were used: G1 (n=6) submitted to sciatica and simulated treatment (placebo group), G2 (n=6) submitted to sciatica and treated with laser 2 J/cm(2), G3 (n=6) submitted to sciatica and irradiated with laser 4 J/cm(2). The hamstring nerve of the animals' right hind limb was exposed and compression with catgut thread in 4 points of the nerve was performed. On the 3rd post-operation day, the treatment was begun with laser in the surgical procedure area of the right hind limb for 10 days. The time during which the limb remained on the air was verified through gait in the following periods: previous to the sciatica, before and after treatment. The results have demonstrated that the laser was not effective in the pain reduction; however, with 4 J/cm(2) there was positive effect, without complete functionality reestablishment.