Neurologic and Histological Study of Clip Compression Model for Rat Thoracic Spinal Cord Injuries

ABSTRACT

OBJECTIVE: The purpose of this study was to assess the time-response of clip compression model for the relationship between the duration of the injury on the rat thoracic spinal cord, and histological and functional outcome measures. METHODS: After laminectomy at T9 in Sprague-Dawley rats, a modified aneurysm clip with a closing force of 30-gram was applied extradurally around the spinal cord at T9, and then rapidly released with cord compression persisting for 1, 5, and 10 minutes, respectively. The locomotor function, according to the Basso-Beattie-Bresnahan (BBB) scale, was assessed weekly for 4 weeks after the injury. The injured spinal cord was then examined histologically including quantification of cavitation. RESULTS: Spinal cord injury by clip compression resulted in worsened BBB scale scores. However, there was spontaneous functional improvement in times for all 3 injury severities, with the greatest improvement in the 1-minute compression group. From 1 week after the injury, BBB scores in the 1-minute group were significantly higher than in the 5 or 10-minutes groups until the end of the follow-up period (p<0.05). For histological analysis, the cavitation area and cavity volume at 4 weeks was directly proportional to the severity of the injury. CONCLUSION: The results of this study show that the rat thoracic cord clip compression model is a reliable and reproducible spinal cord injury model. The duration of clip compression injury in the rat thoracic cord has been correlated with both functional and histologic outcome measures.