[An autopsy case of an extensive epidural spinal abscess demonstrating necrotizing poliomyelopathy]

A 59-year-old man with a history of diabetes mellitus (NIDDM) presented with fever, back pain and weakness in the left lower limb. Three weeks later he suddenly developed flaccid paraklegia, a sensory deficit below the abdomen and sphincter dysfunction. MR images of the spinal cord showed an extensive anterior spinal epidural abscess extending from the seventh cervical to the twelfth thoracic spine and osteomyelitis in the lower thoracic spines. He died of pulmonary infection one year after the disease onset. Postmortem examination revealed a large empyema in the lung. On neuropathological examination, small multiple hemorrhagic or ischemic lesions were found in the basal ganglia and the pons. The spinal cord was markedly atrophic in the lumbar cord. However, there was neither compression deformity in the cord nor occlusion in the anterior spinal artery. Throughout the thoracic cord, rarefaction and focal cavity formation was selectively present in the gray matter, particularly the posterior horns. In the white matter, vacuolar changes were seen peripherally as well as Wallerian degeneration in the lateral and anterior corticospiral tracts and in the fascicles gracilis bilaterally. The mechanisms inducing the cord damage in cases of epidural spinal abscess have been speculated to be either direct compression by the abscess or the secondary circulatory disturbance in the cord due to compression. In our case, the cord showed necrotizing poliomyelopathy, which was similar to that of ischemic myelopathy found in the cases of cardiac arrest or dissecting aneurysm of the aorta. Autopsy study of spinal cord lesion associated with epidural abscess has been limited in number and our case should contribute to the understanding of the pathomechanism of such myelopathy.