Effects of early and delayed laser application on nerve regeneration

Abstract

Studies to understand the operating mechanism of the nervous system and to nd new treatments for its diseases have been growing at an increased pace. To accelerate the rate of regeneration, the laser is used immediately after surgery and the protocols in literature are generally adapted to this method. After crushing or transection of nerve, the mononuclear cells invade the injured segment and remove injured nerve structure. This degenerative event takes place at the rst week after injury. These two critical points gave rise to the question of this study; are there any di erences between early and delayed application? In this regard, three experimental groups underwent surgery (sciatic nerve was damaged by crushing for 10 minutes by applying a force of 50 N using dead-weight machine) and two of which were administrated 14-days of low dose laser irradiation. 650 nm, 25 mW laser irradiation in continuous mode was applied to the early group immediately after injury whereas the therapy started one week after in the delayed group. The healing process of the damaged sciatic nerve has been shown to be accelerated in the laser therapy groups by means of functional, electrophysiological and histological examinations. It was observed that the sciatic functional index (SFI) value of the laser groups approximately reached to the normal whereas the SFI of the control group did not in day 21. However, this nding was not signi cantly important (p>0.05). In addition, it was observed that the latency of the Compound Action Potential (CAP) decreased signi cantly (p<0.05) in the delayed group. Moreover, histological examinations showed that the number of mononuclear cells was lower (p<0.05) in the laser groups. Although further tests are needed to be more conclusive, these results indicate that the laser therapy accelerates the rate of recovery. Both laser groups had positive results. However, the delayed group showed better recovery. This result may be due to the degeneration during the rst-week.