Spinal kyphosis causes demyelination and neuronal loss in the spinal cord

The spinal cord has remarkable ability to resist chronic compression; however, delayed paralysis is sometimes seen following the development of spinal kyphosis. In the past, no animal model to clarify the mechanism of spinal cord damage due to spinal kyphotic deformity has been available. We developed a new experimental model of chronic spinal cord compression using a bird, to evaluate the effects of chronic compression associated with kyphotic deformity of the cervical spine on the spinal cord. As kyphosis progressed, the spinal cord flattening became more marked, causing histopathological changes, including demyelination and neuronal loss. Demyelination of the axons progressed in the order of the anterior, lateral, and then posterior funiculus. Furthermore, microangiography suggested that vascular disturbance in addition to mechanical compression may have contributed to the development of histological changes. In conclusion, progressive kyphosis of the cervical spine resulted in demyelination of nerve fibers in the funiculi and neuronal loss in the anterior horn due to chronic compression of the spinal cord. These histological changes seem to be associated with both continuous mechanical compression and vascular changes in the spinal cord.