A 56 year old man with known hypertension developed a dissecting aneurysm of the aorta accompanied by transient paralysis of the lower extremities. The aneurysm was operated (fenestration procedure) but the next day the dissection extended further distally and the patient became oliguric and completely paraplegic. Sensation of the legs remained relatively intact. He died 14 days after surgery, from rupture of the aorta. Autopsy revealed a dissecting aneurysm extending from the left subclavian artery to the bifurcation of the aorta, with dissection around the intercostal and lumbar arteries. The spinal cord showed selective necrosis of the gray matter with preservation of the white matter in the lower thoracic and upper lumbar segments. The review of the literature suggests that a whole spectrum exists from no cord lesions at all (despite severance of intercostal and lumbar arteries) to massive necrosis of the cord, in extreme cases even with associated necrosis of the vertebral bodies. Selective necrosis such as in the case presented is most likely the result of a “borderline” collateral circulation sufficient to meet the needs of the white matter but unable to cope with the greater oxygen need of the gray matter.