Graded Spinal Cord Contusive Rat Model by a Weight-drop Device

OBJECTIVE: To investigate the reproducibility of graded spinal cord contusion by a weight-drop device, and to establish a graded spinal cord contusive rat model based on the functional analysis and morphometric measurement. METHOD: The weight-drop device developed was composed of impactor with a guidance rod, stereotaxic frame and spine stabilizing device. We investigated the reproducibility of impact by reliability analysis two weeks later. Thirty Sprague-Dawley rats were injured by the weight-drop device from the height of 12.5, 25.0 and 50.0 mm. The three groups of each drop-height (n=10) as well as laminectomized sham group (n=10) were subjected to functional analysis by Basso Beattie Bresnahan Locomotor Scales (BBB scales) and inclined plane test after contusion for four weeks. The morphometric measurement was performed at regularly spaced intervals including the epicenter according to the graded drop-height. RESULTS: The impact of weight-drop was significantly increased according to the drop-height (p <0.05) and revealed high reproducibility. The changes of BBB scales and maximal angle of inclination had an inverse correlation with the contusion severity (p <0.05). There was an inverse correlation between the amount of residual white matter and drop-height (p <0.05). CONCLUSION: The weight-drop device newly developed provides a constant and reproducible spinal cord contusion model.

The Significance of Evoked Potentials according to the Injury Severity of Spinal Cord Contusive Rat Model

OBJECTIVE: To investigate the prognostic values of somatosensory evoked potential (SEP) and electric motor evoked potential (eMEP) studies according to the varying spinal cord injury by incremental height of weight-drop impactor and progress of functional recovery METHOD: Thirty Sprague-Dawley rats (300+/-50 grams, male) were used. The spinal cord injury was made by weight-drop device from 12.5, 25.0 and 50.0 mm height at T10 cord segment. The three groups of each drop-height (n=10) and laminectomized sham group (n=10) were subjected to functional analysis using inclined plane test and Basso Beattie Bresnahan (BBB) locomotor scales at the 1, 3, 5, 7, 14, 21 and 28th day after the contusive injury. SEP by sciatic nerve stimulation and eMEP at the gastrocnemius muscle were recorded. RESULTS: Maximal angle of inclination and BBB scales had an inverse relation with the contusion severity (p <0.05). There were significant correlations among the changes of peak latencies and amplitudes of SEP, contusion severity, and the motor recovery (p <0.05). The changes of onset latencies and amplitudes of eMEP were significantly correlated with the contusion severity and the motor recovery (p <0.05). CONCLUSION: The SEP and eMEP studies had significant values according to the contusion severity and functional recovery in contusive rat model of the spinal cord.