Changes in end-plate vascularity after Nd: YAG laser application to the guinea pig intervertebral disc.

The authors previously have reported the effects of neodymiumyttrium-aluminum-garnet (Nd: YAG) laser on the cartilage end-plates (CEPs) in an animal model. However, there is no experimental study in the literature which specifically addresses the effects of the laser on CEP vascularity. The aim of our study is to investigate the vascular response of the CEP to Nd: YAG laser. In this study, sixteen guinea pigs were used. Experimental intervertebral disc (IVD) degeneration was induced in 12 animals by a ventral disc incision to study the effects of Nd: YAG laser on the CEP of the degenerated IVD from the aspects of pathology and radiology. At 2 months after the experimental annular lesion, the CEP vascular channel counts had increased significantly (p = 0.00) in the cranial CEP to 104%, and to 99% in the caudal CEP. In the early period after laser irradiation the vessel counts from both CEPs decreased due to the extensive damage of Nd: YAG laser on disc tissue (p = 0.00). Accordingly, the value of CEP index and MR signal intensity of the CEPs (cranial and caudal) had decreased one month after laser application. Thereafter, both the CEP vascular channel counts and the MR signal intensity remained relatively constant throughout the course of the experiment, but the value of CEP index had increased to 68% of the normal IVD. From the results of present study, it is evident that laser application had a significant negative influence on the CEP vascularization of the degenerated IVD.