Transverse Myelitis
Transverse myelitis is a neurological disorder caused by inflammation across both sides
of one level, or segment, of the spinal cord. The term myelitis refers to
inflammation of the spinal cord; transverse simply describes the position of the
inflammation, that is, 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 transverse myelitis 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. Although some
patients recover from transverse myelitis with minor or no residual problems, others
suffer permanent impairments that affect their ability to perform ordinary tasks of daily
living. Most patients will have only one episode of transverse myelitis; a small
percentage may have a recurrence.
The segment of the spinal cord at which the damage occurs determines which parts of the
body are affected. Nerves in the cervical (neck) region control signals to the neck, arms,
hands, and muscles of breathing (the diaphragm). Nerves in the thoracic (upper back)
region relay signals to the torso and some parts of the arms. Nerves at the lumbar
(mid-back) level control signals to the hips and legs. Finally, sacral nerves, located
within the lowest segment of the spinal cord, relay signals to the groin, toes, and some
parts of the legs. Damage at one segment will affect function at that segment and segments
below it. In patients with transverse myelitis, 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.
Causes & symptoms of Transverse myelitis
Transverse myelitis has many different causes, often triggered by a variety of viral
and bacterial infections (especially those associated with a rash such as measles or
chickenpox). Once the infection subsides, the inflammation in the cord begins. About a
third of patients experience a flu-like illness with fever about the time they develop
symptoms of TM. Sometimes, there appears to be a direct invasion of, and injury to, the
spinal cord by an infectious agent (such as herpes zoster or the AIDS virus).
TM can also accompany a variety of diseases that break down tissue that surrounds and
insulates the nerves (demyelinating diseases), such as multiple sclerosis (MS).
Some toxic substances, such as carbon monoxide, lead, or arsenic, can cause a type of
myelitis characterized by inflammation followed by hemorrhage or bleeding that destroys
the entire circumference of the spinal cord. Other types of myelitis can be caused by
poliovirus; herpes zoster; rabies, smallpox or polio vaccination; or parasitic and fungal
infections.
Many experts believe that TM can occur without any apparent cause, probably as the
result of an autoimmune process. This means that a person's immune system attacks the
spinal cord, causing inflammation and tissue damage.
Regardless of the cause of the myelitis, onset of symptoms is sudden and rapid.
Problems with movement and sensation appear within one or two days after inflammation
begins. Symptoms include soft (flaccid) paralysis of the legs, with pain in the lower legs
or back, followed by loss of feeling and sphincter (muscles which close an opening, as in
the anus) control. The earliest symptom may be a girdle-like sensation around the trunk.
The extent of damage occuring will depend on how much of the spinal cord is affected,
but TM rarely involves the arms. Severe spinal cord damage also can lead to shock.
Diagnosis
A doctor will suspect transverse myelitis in any patient with a rapid onset of
paralysis. Medical history, physical examination, brain and spinal cord scans, myelogram,
spinal tap, and blood tests are used to rule out other neurological causes of symptoms,
such as a tumor. If none of these tests suggest a cause for the symptoms, the patient is
presumed to have transverse myelitis.
How is Transverse Myelitis treated
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. Although no
clinical trials have investigated whether corticosteroids alter the course of transverse
myelitis, these drugs often are prescribed to reduce immune system activity because of the
suspected autoimmune mechanisms involved in the disorder. Corticosteroid medications that
might be prescribed may include methylprednisone or dexamethasone. General analgesia will
likely be prescribed for any pain the patient may have. And bedrest is often recommended
during the initial days and weeks after onset of the disorder.
Following initial therapy, the most critical part of the treatment for this disorder
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. Often, even before
recovery begins, caregivers may be instructed to move patients’ limbs manually to
help keep the muscles flexible and strong, and to reduce the likelihood of pressure sores
developing in immobilized areas. Later, if patients begin to recover limb control,
physical therapy begins to help improve muscle strength, coordination, and range of motion
Prognosis
The prognosis depends on how much of the cord was damaged. Some people recover
completely, while others have lasting problems and need help in learning how to cope with
activities of daily living. People who develop spastic reflexes early in the course of the
condition are more likely to recover than those who do not. If spinal cord tissue death
(necrosis) occurs, the chance of a complete recovery is poor. Most recovery occurs within
the first three months. A certain percentage of patients with TM will go on to develop
multiple sclerosis. |
