Degenerative myelopathy in three strains of aging rats.

Spontaneous paresis and paralysis associated with degenerative spinal cord and spinal nerve root lesions occurred in three strains of rats used in studies of aging. Focal or segmental spinal cord lesions had mild to severe demyelination, loss of nerve axons, and lipid-filled gitter cells. The lesions were limited to the white matter and were most severe in the lateral and ventral funiculi. The nerve roots had cholesterol clefts, focal hemorrhage, and demyelination. Atrophy of the skeletal muscle probably was secondary to the cord lesions. Vertebral lesions that involved the spinal canal and vascular blood flow were found, which may explain pathogenesis.