[A chronic spinal cord compression model in a rat with a 354A tumor].

Abstract

A posterior spinal cord compression model was produced in a rat with a 354 A tumor. Here we report the compression process using MRI (at 2.11 tesla), the progression of paralysis in the posterior limbs, the pathological changes in the neural tissues, and the spinal evoked potentials (SpEPs). A relatively flat spinal cord compression model was established by the interposition of free fatty tissue between the tumor and dura mater. The anteroposterior diameter of the compressed cord (AP), the width of the compressed cord (W), the cross-sectional areas of the spine (A), the mean of the anteroposterior diameters of the cord at the levels of the adjacent cephalic and caudal vertebral bodies (AP), and the mean of the cross-sectional areas of the cord at the levels of the adjacent cephalic and caudal vertebral bodies (A) were measured on axial views from MRI. Paralysis of the posterior limbs occurred in this model when A/A became less than 60%, AP/AP became less than 35% and AP/W became less than 20%. Pathological changes became apparent in the neural tissues when A/A became less than 50-60%, AP/AP became less than 25-30% and AP/W became less than 15%. Polyphasic wave-forms were noted when A/A became less than 60%, AP/AP became less than 35% and AP/W became less than 20%. When the A/A became less than 40%, the histopathological changes became marked. SpEPs could no longer be detected at this degree of compression, indicating that all neural conduction had been blocked.