Functional and structural recovery of injured spinal cord following delayed X-irradiation in rats.

Objective: To test the hypothesis that delayed X-irradiation can enhance the functional and structural recovery of the injured spinal cord in rats.

Methods: Seventy Sprague-Dawley rats were randomly divided into two groups, 35 rats in each. The control group sustained a one-minute clip compression (force of clip was 30 g) injury of the spinal cord at the T2 level, without X-irradiation. The experimental group received X-irradiation 14 days after injury. Neurological function was assessed by the modified Tarlov method, including hind limbs movement, inclined plane, and pain withdrawal. These tests were performed in a blinded fashion at 3, 7, 14, 21, 28, 35, and 42 days after injury. At 43 days after injury, histological examination of the injured spinal cord was performed following decapitation of the rats.

Results: Sixty-two rats met the experimental requirements (spinal cord injury was similar), 32 rats in experimental group and 30 rats in control group. Statistically significant difference was observed between the two groups in hind limbs movement and inclined plane (P < 0.01), but not in the pain withdrawal test. The edema and necrosis areas of injured spinal cords in experimental group were less than those in control group, and axons in experimental group were significantly more than those in control group (P < 0.01).

Conclusion: Delayed X-irradiation following spinal cord injury may enhance functional recovery by improving and restoring structural integrity of the injured spinal cord in rats.