Acute transverse myelitis is inflammation that affects the spinal cord across its entire width (transversely) and thus blocks transmission of nerve impulses traveling up or down the spinal cord.
In the United States, acute transverse myelitis is estimated to occur in about 1,400 people each year. Also, about 33,000 people are thought to have some type of disability due to the disorder. The entire width of one or more areas of the spinal cord, usually in the chest (thoracic area), becomes inflamed.
What triggers acute transverse myelitis is unknown, but it may result from an autoimmune reaction (when the immune system misinterprets the body's tissues as foreign and attacks them). The disorder may develop during the following:
- Multiple sclerosis (most commonly)
- Neuromyelitis optica, a disorder that can also cause visual problems and may come and go
- Certain bacterial infections (such as Lyme disease, syphilis, or tuberculosis)
- Inflammation of blood vessels (vasculitis), including lupus (systemic lupus erythematosus)
- Viral meningoencephalitis (an infection of the brain and its surrounding tissues)
- Use of certain antiparasitic or antifungal drugs
- Intravenous injection of heroin or amphetamines
It sometimes develops after mild viral infections or a vaccination.
Usually, symptoms begin suddenly with pain in the back and a bandlike tightness around the affected area of the body (such as the chest or abdomen). Within hours to a few days, tingling, numbness, and muscle weakness develop in the feet and move upward. Urinating becomes difficult, although some people feel an urgent need to urinate (urgency). Symptoms may worsen over several more days and may become severe, resulting in paralysis, loss of sensation, retention of urine, and loss of bladder and bowel control. The degree of disability depends on the location (level) of the inflammation in the spinal cord and the severity of the inflammation.
Symptoms suggest the diagnosis. But doctors must distinguish acute transverse myelitis from other disorders that cause similar symptoms, such as Guillain-Barré syndrome, spinal cord compression, or blockage of the blood supply to the spinal cord. Magnetic resonance imaging (MRI) is done first. If MRI does not detect spinal cord compression, a spinal tap (lumbar puncture) is done to obtain a sample of spinal cord fluid. If acute transverse myelitis is present, the number of certain white blood cells and the protein level in the fluid is increased. If the disorder is advanced, MRI typically shows swelling of the spinal cord due to inflammation.
Tests, such as a chest x-ray and blood tests, are also done to look for causes. Doctors may also ask people about use of drugs.
Occasionally, the disorder recurs in people with multiple sclerosis or lupus. Multiple sclerosis eventually develops in about 10 to 20% of people who have transverse myelitis with no identified cause.
Generally, the more quickly the disorder progresses, the worse the outlook. Severe pain suggests worse inflammation. The outcome is split evenly:
- About one third of people recover.
- About one third continue to have some muscle weakness and urinary problems (urgency or loss of bladder control).
- About one third recover very little, remaining confined to a wheelchair or bed, continuing to have bladder and bowel problems, and requiring help with daily activities.
If transverse myelitis is caused by another disorder, that disorder is treated.
If the cause cannot be identified, high doses of corticosteroids such as prednisone are often given to suppress the immune system, which may be involved in acute transverse myelitis. Plasma exchange—removal of a large amount of plasma (the liquid part of blood) plus plasma transfusions—may also be done. However, whether these treatments are useful is unclear.
Symptoms are treated.
Adapted from: Merck & Co. Inc.