Further Standardization in the Aneurysm Clip: The Effects of Occlusal Depth on the Outcome of Spinal Cord Injury in Rats.

Abstract

Experimental study. To evaluate the relationship between clip occlusal depth and functional and histological outcome measures in a rat model of thoracic spinal cord injury (SCI). Aneurysm clip compression is a proven model of contusion-compression SCI, but the relationship between clip depth and outcomes in thoracic SCI is unknown. A single aneurysm clip was applied to the spinal cord at thoracic vertebra 10 for 1 minute with an occlusal depth of 2, 6, or 10 mm. The actual compression force was measured using a self-made pulling method. Locomotor function was assessed for 28 days using Basso, Beattie, and Bresnahan (BBB) and inclined plane test (IPT) scores. We then used hematoxylin-eosin and Luxol fast blue staining to histologically quantify cavitation formation, preserved white matter, and preserved grey matter. Greater occlusal compression depths caused greater actual compression forces and worsened functional and histological recovery. The 2- and 10-mm clip injury groups had significantly different BBB and ITP scores; cavitation, preserved white matter, and preserved grey matter volumes; and actual force measures (P < 0.05). Our findings show that the occlusal depth of clip compression correlates with actual compression force and recovery impairment. 1.