Effects of early and delayed laser application on nerve regeneration

Abstract

Sinir sistemi çalışma mekanizmasını anlama ve sinir sistemi hastalıklarına yonelik tedavi yontemleri üzerine calışmalar büyük hız kazanmıştır.Sinir yenilenmesini hızlandırmak için kullanılan laser, zedelenmeden hemen sonra uygulanmaktadir ve literatürdeki protokollerin genel olarak bu yöntemi kullanmaktadır. Sinir kopması veya zedelenmesinden sonra, mononküler hüccreler zedelenmiş, bölgeye akın ederek bu bolgeyi ortadan kaldırır. Bu siirec hasardan sonraki ilk bir hafta igerisinde gerçekleşir. Bu iki önemli bilgi şu sorunun dogmasına neden olmuşttur; erken ve gee laser uygulamalan arasmda herhangi bir fark var mi? Bu baglamda, tic deneysel grupta liasar meydana getirilmi§ (siyatik sinir 50 N uygulayan bir alet yardimiyla 10 dakika ezilmiştir) ve iki gruba 14 gun boyunca dusuk doz laser uygulanmiştir. 650 nm 25 mW lik devamlı kipteki laser erken grubuna hasardan hemen sonra, gee grubuna ise hasardan 1 hafta sonra uygulanmiştir. Fonksiyonel, elektrofizyolojik ve histolojik gozlemler yardimiyla laser uygulanan gruplarda zedelenen sinirin iyileşme surecinin hizlandigi gosterilmiştir. 21.günde, laser grubunun SFI degerleri normale yaklaşirken, kontrol grubu yaklaşamadigi gozlemlenmiştir. Ancak bu bulgu istatiksel olarak anlamli degildi (p>0.05). Aynca, gee grubun Bileşik aksiyon potansiyel ait latans degerinin onemli olçüde azaldigi gozlemlendi (p<0.05). Son olarak kullanılan histolojik gözlemler ise laser grubunda mononükleer hucre sayisnın daha az oldugunu gostermiştir (p<0.05).Her ne kadar kesin bir sonuca varmak igin başka testlere gerek duyulsa da, elde edilen sonuçlar laserin iyileşme siirecini hizlandirdigini gostermektedir. Iki laser grubunda da pozitif sonuclar elde edilmiştir. Ancak, beş grup daha hizlı iyileşme gostermiştir. Bu sonuc ilk haftanın dejeneratif sürece ait olmasından kaynaklanabilir.Anahtar Sozcükler: sinir yenilenmesi, laser, siyatik fonksiyonel indeks

Studies to understand the operating mechanism of the nervous system and to find new treatments for its diseases have been growing at an increased pace. To accelerate the rate of regeneration, the laser is used immediately after surgeryand 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 first week after injury. These two critical points gave rise to the question of this study; are there any differences 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 finding was not significantly important (p>0.05). In addition, it was observed that the latency of the Compound Action Potential (CAP) decreased significantly (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 first-week.Keywords: nerve regeneration, laser, sciatic functional index