Correlation of clinical and electrophysiological findings of experimental spinal cord injury in rats

Abstract

Introduction: The experimental spinal injury at sacral level in rats provides an animal model with low morbidity than others with lesion at higher metameric levels. The information in literature concerning clinical quantification of tail spasticity in rats due to lesion at sacral level is scarce. There are no studies correlating the degree of tail spasticity with electrophysiological responses in an experimental animal model lesioning the spinal cord at this level. The purpose of this study is to evaluate the spasticity of rat tail using a clinical scale and validate it though the correlation with electrophysiological findings.

Materials and methods: Experimental spinal cord surgeries at a metameric sacral level were performed in Sprague Dawley rats to produce spasticity circumscribed to the tail. We followed up the specimens postoperatively with clinical and electrophysiological recordings, and categorized the spasticity with a semi quantitative scale. The electrophysiological registra- tions (M and F waves) were taken in the tail. Finally, the rats were sacrificed and verified the lesion with histopathology.

Results: All the animals with spinal lesion presented tail paresis after the second week. The results were the followings: five rats presented spasticity grade 2; one rat presented grade 3; and the last three, grade 4.The electrophysiology showed pattern responses correlated with the clinical evolution of spasticity.

Discussion: The present investigation showed the correlation between the degree of spasticity and the electrophysiological recordings, which indicate the grade of excitability of alpha motoneurons.

Conclusions: These models allow performing a semi quantitative evaluation of the clinical degree of spasticity and correlate it with electrophysiology.