CHANGES IN END-PLATE VASCULARITY AFTER ND-YAG LASER APPLICATION TO THE GUINEA-PIG INTERVERTEBRAL DISC

The authors previously have reported the effects of neodymium-yttrium- aluminum-garnet (Nd: YAG) laser on the cartilage endplates (CEPs) in a n animal model. However, there is no experimental study in the literat ure which specifically addresses the effects of the laser on CEP vascu larity. The aim of our study is to investigate the vascular response o f the CEP to Nd: YAG laser. In this study, sixteen guinea pigs were us ed. 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 p eriod after laser irradiation the vessel counts from both CEPs decreas ed 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 th e CEPs (cranial and caudal) had decreased one month after laser applic ation. Thereafter, both the CEP vascular channel counts and the MR sig nal intensity remained relatively constant throughout the course of th e experiment, but the value of CEP index had increased to 68% of the n ormal IVD. From the results of present study, it is evident that laser application had a significant negative influence on the CEP vasculari zation of the degenerated IVD.