Morphologic change and glial response to unilateral spinal cord compression

In cervical myelopathy, unilateral compression of the spinal cord would be expected to produce Brown-Séquard syndrome. However, transverse lesion syndrome occurs in most clinical cases. In order to reveal the mechanism by which unilateral compression induces transverse damage to the spinal cord, damage of the gray and white matter in each half of the spinal cord was examined precisely using the density of reactive glial cells. The cervical spinal cord in rabbits was unilaterally compressed with a small screw. The area of each half of the damaged cord and the densities of GFAP-positive astrocytes and reactive microglias of the compressed and contralateral halves were investigated. As the compression increased, the area of the compressed half of the spinal cord decreased significantly compared to the contralateral half. The densities of GFAP-positive astrocytes in the gray matter and the anterior funiculus significantly increased in the compressed half. There were no significant differences in the densities at the lateral and dorsal funiculi between the compressed and contralateral halves. The tissue damage in the gray matter of the compressed half was markedly higher. These findings provide evidence for the mechanistic basis of spinal cord damage that leads to transverse lesion syndrome in unilateral compression myelopathy.