Functional outcomes after spinal cord contusion injury in rats: the influence of age and key parameters.

The complexity of sensory and motor dysfunctions following spinal cord injury (SCI) necessitates identifying key physical parameters that contribute to these outcomes. This paper examines the effects of critical parameters on behavioral and physiological outcomes after spinal contusion in preadolescent (7 weeks) and adult (30 weeks) male Sprague-Dawley rats. A standardized injury of 150-kilodyne force and 1-second dwell time was induced at thoracic level 10. Actual Force (152.6 ± 0.6 and 154.4 ± 1.2 kdyn) and Velocity (121 ± 0.4 and 120.7 ± 0.6 mm/s) were consistent between groups, although Displacement (981.5 ± 35.9 and 1048.6 ± 30.4 µm) varied. The preadolescent group showed more rapid body weight loss (POD 4 vs. POD 7) and quicker locomotion recovery (POD 16 vs. POD 22), while the adult group exhibited a faster onset of bladder dysfunction. By 40 days post-injury, all groups developed mechanical allodynia (p < 0.05), with thermal hyperalgesia significantly elevated in the preadolescent group (p < 0.05). Analysis of displacement subsets revealed that both Low and high-displacement groups had similar levels of mechanical allodynia; however, the high-displacement group experienced greater impairments in body weight, locomotion, and bladder function. These findings highlight age and spinal displacement as critical factors in evaluating consistent behavioral dysfunctions following SCI in rats.