Transverse myelitis (TM) is a neurological disorder caused by inflammation across one segment of the spinal cord. The term myelitis refers to inflammation of the spinal cord; transverse simply describes the position of the inflammation, across the width of the spinal cord. Attacks of inflammation can damage or destroy myelin, the fatty insulating substance that covers nerve cell fibers. This damage causes nervous system scars that interrupt communications between the nerves in the spinal cord and the rest of the body.
Symptoms of TM include a loss of spinal cord function over several hours to several weeks. What usually begins as a sudden onset of lower back pain, muscle weakness, or abnormal sensations in the toes and feet can rapidly progress to more severe symptoms, including paralysis, urinary retention, and loss of bowel control.
Some people recover from TM with minor or no residual problems, others suffer permanent impairments that affect their ability to perform ordinary tasks of daily living.
Demyelination usually occurs at the thoracic level, causing problems with leg movement and bowel and bladder control, which require signals from the lower segments of the spinal cord.
Transverse myelitis occurs in adults and children, in both genders, and in all races. No familial predisposition is apparent. The peak number of new cases per year appears to occur between 10 and 19 years and 30 and 39 years. About 1,400 new cases of transverse myelitis are diagnosed annually in the United States, and approximately 33,000 Americans have some type of disability resulting from TM.
The exact causes of transverse myelitis are not known. The inflammation that damages the spinal cord may result from viral infections, abnormal immune reactions, or insufficient blood flow through the blood vessels located in the spinal cord. Transverse myelitis also may occur as a complication of syphilis, measles, Lyme disease, and some vaccinations, including those for chickenpox and rabies.
Transverse myelitis often develops following viral infections due to varicella zoster (the virus that causes chickenpox and shingles), herpes simplex, cytomegalovirus, Epstein-Barr, influenza, echovirus, human immunodeficiency virus (HIV), hepatitis A, or rubella. Bacterial skin infections, middle-ear infections and bacterial pneumonia have also been associated with the condition.
In post-infectious cases of TM, it is believed that the immune system, which normally protects the body from foreign organisms, mistakenly attacks the body’s own tissue, causing inflammation and, in some cases, damage to myelin within the spinal cord.
Transverse myelitis may be either acute (developing over hours to several days) or subacute (developing over 1 to 2 weeks). Four classic features of transverse myelitis emerge: (1) weakness of the legs and arms, (2) pain, (3) sensory alteration, and (4) bowel and bladder dysfunction. Most patients will experience weakness of varying degrees in their legs; some also experience it in their arms. Progression of the disease over several weeks often leads to full paralysis of the legs, requiring the use of a wheelchair.
Pain is the primary symptom of transverse in about half of all patients. The pain may be localized in the lower back or may consist of sharp, shooting sensations that radiate down the legs or arms or around the torso. Up to 80 percent of those with transverse myelitis report areas of heightened sensitivity to touch, such that clothing or a light touch with a finger causes significant discomfort or pain (a condition called allodynia). Many also experience heightened sensitivity to changes in temperature or to extreme heat or cold.
Physicians diagnose transverse myelitis by taking a medical history and performing a thorough neurological examination.
As with many disorders of the spinal cord, no effective cure currently exists for people with transverse myelitis. Treatments are designed to manage and alleviate symptoms and largely depend upon the severity of neurological involvement. Therapy generally begins when the patient first experiences symptoms. Physicians often prescribe corticosteroid therapy during the first few weeks of illness to decrease inflammation.
Following initial therapy, the most critical part of treatment for TM consists of keeping the patient’s body functioning while hoping for either complete or partial spontaneous recovery of the nervous system. This may sometimes require placing the patient on a respirator.
Patients with acute symptoms, such as paralysis, are most often treated in a hospital or in a rehabilitation facility where a specialized medical team can prevent or treat problems that afflict paralyzed patients. Later, if patients begin to recover limb control, physical therapy begins to help improve muscle strength, coordination, and range of motion.
Recovery from transverse myelitis usually begins within 2 to 12 weeks of the onset of symptoms and may continue for up to 2 years. However, if there is no improvement within the first 3 to 6 months, significant recovery is unlikely. About one-third of people affected with transverse myelitis experience good or full recovery from their symptoms. Another one-third show fair recovery and are left with deficits such as spastic gait, sensory dysfunction, and prominent urinary urgency or incontinence. The remaining one-third show no recovery at all, using wheelchairs, perhaps with marked dependence on others for basic functions of daily living.
The National Institute of Neurological Disorders and Stroke (NINDS) supports research to clarify the role of the immune system in TM and other autoimmune diseases or disorders. Other work focuses on strategies to repair demyelinated spinal cords including approaches using cell transplantation. The ultimate goals of these studies are to encourage the same regeneration in humans and to restore function to paralyzed patients.
Source: National Institute of Neurological Disorders and Stroke (NINDS), Transverse Myelitis Association