Assessment of motor recovery and MRI correlates in a porcine spinal cord injury model

The study concentrated on behavioral and magnetic resonance imaging (MRI) characteristics in a porcine spinal cord injury model. Six adult minipigs weighing 32-35 kg were narcotized by thiopental, intubated, and placed on a volume-cycled ventilator. Anaesthesia was maintained by 1.5% sevoflurane with oxygen. Following location of the 1st lumbar vertebra animals were fastened in an immobilization frame. The spinal cord, exposed through a laminectomy, was compressed by a 5 mm thick circular rod with a peak force of 0.8 kg at a velocity of 3 cm.s(-1). The next day the minipigs were paraplegic but improved rapidly to paraparesis. On the 12th postoperative day they were euthanasied. Neural tissue changes were evaluated by post mortem MRI, which showed damage to the spinal cord white and/or gray matter in the epicentre of compression with longitudinal spreading over one segment cranially and caudally. Statistical analyses performed by Spearman's rho test revealed positive correlations between damaged areas and the whole area of the spinal cord white/gray matter (P = 0.047; r(s) = 0.742) and (P = 0.002; r(s) = 0.943), respectively. The study confirmed the reliability and reproducibility of the utilised model of spinal cord trauma. The structural changes in the epicentre of injury did not impede the rapid but incomplete recovery of motor functions.