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Blockage of an artery carrying blood to the spinal cord prevents the cord from getting blood and thus oxygen. As a result, tissues can die (called infarction).

Like all tissues in the body, the spinal cord requires a constant supply of oxygenated blood. Only a few arteries, which are branches of the aorta, supply blood to the front part of the spinal cord. But this blood accounts for three fourths of the blood the spinal cord receives. Thus, blockage of any one of these arteries can be disastrous. Such a blockage occasionally results from the following:

• Severe atherosclerosis of the aorta
• Separation of the layers of the aorta's wall (aortic dissection)
• Inflammation of blood vessels (vasculitis), such as polyarteritis nodosa
• A blood clot that breaks off from the wall of the heart and travels through the bloodstream (becoming an embolus)
• Surgery to repair a bulge (aneurysm) in the abdominal aorta

Symptoms

The first symptoms are usually sudden back pain and pain that radiates along the nerves branching from the affected area of the spinal cord. The pain is followed by muscle weakness, and people cannot feel heat, cold, or pain in areas controlled by the part of the spinal cord below the level of the blockage. People immediately notice symptoms, which may lessen slightly over time. If the blood supply to the front of the spinal cord is greatly reduced, the legs are numb and paralyzed. But sensations transmitted through the back of the cord—including touch, the ability to feel vibration, and the ability to sense where the limbs are without looking at them (position sense)—remain intact. The back of the cord receives blood from other sources.

Weakness and paralysis can lead to the development of pressure sores and breathing difficulties. Bladder and bowel function may be impaired, as may sexual function.

Diagnosis

The diagnosis is usually based on symptoms. Magnetic resonance imaging (MRI) or, if MRI is unavailable, myelography (see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Myelography) is done. These tests can help doctors rule out other disorders that cause similar symptoms. A spinal tap (lumbar puncture—see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: How a Spinal Tap Is Done) may be done to rule out transverse myelitis as the cause of symptoms. Angiography can confirm that an artery to the front of the spinal cord is blocked, but it is usually unnecessary.

Treatment

When possible, the cause (such as aortic dissection or polyarteritis nodosa) is treated, but otherwise, treatment focuses on relieving symptoms because paralysis and spinal cord dysfunction are usually permanent.

Because some sensations are lost and paralysis may develop, preventing pressure sores from forming is important. Therapy to help fluids drain from the lungs (such as deep breathing exercises, postural drainage, and suctioning) may be necessary. Physical and occupational therapy (see Rehabilitation: Physical Therapy (PT)) can help preserve muscle function. Because bladder function is usually impaired, a catheter is needed to drain urine. This treatment prevents the bladder from enlarging and forming bulges that weaken it.