STUDY OF EXPERIMENTAL CERVICAL SPONDYLOTIC MYELOPATHY

Most cervical spondylotic myelopathy cases show insidious onset. Experimental cervical spondylotic myelopathy models were made using cats to analyze advancing patterns of myelopathy in the spinal cord and to identify the most responsible factor. Spinal cord compression was applied anteriorly using one screw through the C5 vertebral body or three screws through the C4, C5, and C6 vertebral bodies. Every few weeks, the screws were turned approximately 1 mm at a time up to approximately 50% of the spinal canal. At more than 6 months after final compression, limb function and evoked spinal cord potentials were evaluated. Thereafter, histologic examinations were performed. The results: the single compression group showed normal limb function, but the multiple compression group showed sluggish gait. Histologically, mild neuronal decrease in the gray matter was noticeable in the single compression group. Conversely, the multiple compression group showed severe changes in the gray matter and significant changes in the posterior and anterior columns. There was a correlation between the evoked spinal cord potentials and histologic changes. It was clear that multiple compressions to the spinal cor caused more severe deterioration functionally and electrophysiologically as well as histologically than a single compression.