Pathologic Observation In Different Degree Of Injury In Spinal Cord Injury Model

Objective:Spinal cord injuries are devastating and generally result in severe long-term disability. In the hours and days after SCI, nerve cells that survive the initial injury may still be at risk for damage. Many neurons die not from the initial trauma but in a process called "secondary" injury. Inflammation has been widely perceived as participating in the etiology of acute and chronic neurodegenerative conditions. The objective of this study is to determine whether there is a relationship between the duration and weight of sustained spinal cord compression and the extent of spinal cord injury and the capacity for functional recovery after decompressionMethods: Under general anesthesia, rats were subjected to a laminectomy a T10-12 vertebral level , after which different weight and timming was dropped onto a force transducer and impounder resting on the spinal cord; the time and weight drop varied in different groups; 5 g for 5,15 minute(group A ) ; 15 g for 5,15 minutes ( group B ); 50 g for 5,15minutes (group C ). The animals were observed for 6 weeks postinjury.Neurologic recovery was monitored by Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale.For morphometric and Immunihistochemical analysis thick longitudinal sections (4μm) were stained with H.E stain, NF, dMBPResults: Sustained spinal cord compression was associated with a gradual decline in interface pressure and time. Despite this, there was continuous decline in the motor function. Within group A after the decompression had recovery of hind limb motor function within 1 week (BBB 21/21), but no animal had such recovery in the group C. Within 6 weeks after the injury, balance, cadence, stair-climbing, and the ability to walk up an inclined plane were significantly better in the A and B group than in the C group. The results of the time and weight until decompression demonstrated that the motor scores were consistently better the shorter the durationlow weight of SCI (P < 0.05) for each of the groups (A,B,C ) over the 6-week recovery period. Histologic analysis by light microscopic examination of the spinal cord in the region in different weight and duration induce SCI, spinal cord specimens showed significant changes in the architecture. The damage was most severe in the rats with spinal cord injury with 50 gm. Cross sectional views demonstrated significant damage within spinal cord, which caused injury to the dorsal columns of the spinal cord, in longitudinal section characterized by cavitation, marginal gliosis, and atrophy .To evaluate the extent of damage to neuronal processes, we examined the immunoreactivity of injured spinal cord sections for dMBP ( 1: 400 ) and NF(1:200). Immunohistochemical staining with NF and dMBP showed that C2 group had low staining in NF immunohistochemistry than A1 group and C2 had dMBP strong staining than other group . Histologic analysis showed more severe spinal cord damage as both weight and the time until decompression increased. The longer duration and heavy weight of compression produced lesions of significantly greater volume, which corresponded to the long-term functional outcome.Conclusions: The relatively rapid viscoelastic relaxation of the spinal cord during the early phase of sustained cord compression suggests that there are...