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Transverse Myelitis
Transverse myelitis (TM) 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 entire width of the spinal cord.

TM may be either acute (developing over hours to several days) or subacute (usually developing over 1 to 4 weeks). 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 or block transmission of nerve impulses traveling up or down the spinal cord.

The first cases of acute myelitis were described in 1882 and were attributed to vascular lesions and acute inflammatory events. In England between 1922 and 1923 more than 200 postvaccinial cases were noted as complications of the smallpox and rabies vaccines. Later reports revealed that TM was post-infectious in nature, and agents including measles, rubella and mycoplasma were directly isolated from patient’s spinal fluid. The term "acute transverse myelitis" (ATM) was first used by an English neurologist in 1948 to describe a case of rapidly progressive paraparesis with a thoracic sensory level, occurring as a postinfectious complication of pneumonia.

In the United States, ATM 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.

Transverse myelitis occurs in adults and children, in both genders, and in all races. No familial predisposition is apparent. A peak in incidence rates (the number of new cases per year) appears to occur between 10 and 19 years and 30 and 39 years. Although only a few studies have examined incidence rates, it is estimated that about 1,400 new cases of transverse myelitis are diagnosed each year in the United States, and approximately 33,000 Americans have some type of disability resulting from the disorder.

Many feel it's appropriate to discuss the relationship between TM and multiple sclerosis (MS):
The first reason is that people with TM tend to end up seeing MS specialists as neurologists. MS is a common inflammatory disease of the central nervous system (CNS) where as the incidence of TM is much less in the range of 1 to 5 per million. Many neurology specialists in MS also see people with other inflammatory or immunologic disorders of the spinal cord. MS specialists have experience treating problems associated with spinal cord disease. Therefore, the clinicians who see and treat people with TM can't help but use the knowledge they have about the causes and pathology of MS.
The second reason is the fact that many people view ATM as one manifestation of a larger group of demyelinating illnesses (a large related family). ATM is felt to be part of a spectrum of CNS demyelination. It's also felt that MS is almost certainly not a single disease but just a part of a series of idiopathic inflammatory demyelinating diseases (IIDD).
The third reason is that a small number of people with ATM are actually experiencing their first attack of MS. It's been estimated that 40 to 50% of first attacks of MS are monosymptomatic or consist of neurologic symptoms, which can be caused by a single lesion in the CNS. Spinal cord attacks are characteristic of MS but the syndrome of complete ATM is unusual as an initial symptom of MS.

Cause of Transverse Myelitis

The exact causes of TM is not known, however, it's believed that the inflammation that causes such extensive damage to nerve fibers of the spinal cord may result from viral infections or abnormal immune reactions. TM also may occur as a complication of other conditions. Cases in which a cause can't be identified are called idiopathic.

Understanding the types of ATM can help. There are two main types: acute partial transverse myelitis (APTM) and acute complete transverse myelitis (ACTM). In APTM, the inflammation typically extends only partway across the spinal cord. People with APTM may have mild to moderate muscle weakness and odd sensory symptoms. The bladder also can lose functioning. In ACTM, inflammation affects the full width of the spinal column. Moderate or severe loss of body functioning can occur.

In post-infectious cases of TM, immune system mechanisms, rather than active viral or bacterial infections, appear to play an important role in causing damage to spinal nerves. Although researchers have not yet identified the precise mechanisms of spinal cord injury in these cases, stimulation of the immune system in response to infection indicates that an autoimmune reaction may be responsible. In autoimmune diseases, 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.

In some people, TM represents the first symptom of an underlying demyelinating disease of the CNS such as MS or neuromyelitis optica (NMO). A form of transverse myelitis known as "partial" myelitis, because it affects only a portion of the cross-sectional area of the spinal cord, is more characteristic of MS. NMO typically causes both TM and optic neuritis (inflammation of the optic nerve that results in visual loss), but not necessarily at the same time. All those with TM should be evaluated for MS or NMO because patients with these diagnoses may require different treatments, especially therapies to prevent future attacks.

Symptoms

Initial symptoms usually include localized lower back pain, sudden paresthesias (abnormal sensations such as burning, tickling, pricking, or tingling) in the legs, sensory loss, and paraparesis (partial paralysis of the legs). 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.

Paraparesis may progress to paraplegia (paralysis of the legs and lower part of the trunk). Urinary bladder and bowel dysfunction is common. Many patients also report experiencing muscle spasms, a general feeling of discomfort, headache, fever, and loss of appetite. Depending on which segment of the spinal cord is involved, some patients may experience respiratory problems as well.

From this wide array of symptoms, four classic features of TM emerge:
1) Weakness of the legs and arms
2) Pain
3) Sensory alteration
4) Bowel and bladder dysfunction

Most will experience weakness of varying degrees in their legs; some also experience it in their arms. Initially, people with TM may notice that they are stumbling or dragging one foot or that their legs seem heavier than normal. Coordination of hand and arm movements, as well as arm and hand strength may also be compromised. Progression of the disease leads to full paralysis of the legs, requiring the patient to use a wheelchair.

Pain is the primary presenting symptom of TM in approximately one-third to one-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.

Those who experience sensory disturbances often use terms such as numbness, tingling, coldness, or burning to describe their symptoms. Up to 80% of those with TM 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.

The degree of disability depends on the location (level) of the inflammation in the spinal cord and the severity of the inflammation. 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 TM, 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.

Diagnosis

Physicians diagnose TM by taking a medical history and performing a thorough neurological examination. Because it's often difficult to distinguish between a patient with an idiopathic form of TM and one who has an underlying condition, physicians must first eliminate potentially treatable causes of the condition.

When a spinal cord problem is suspected, physicians seek first to rule out structural lesions (damaged or abnormally functioning areas) that could cause spinal cord compression or otherwise affects its function. Such potential lesions include tumors, herniated or slipped discs, stenosis (narrowing of the canal that holds the spinal cord), abscesses, and abnormal collections of blood vessels.

To rule out such lesions and check for inflammation of the spinal cord, patients often undergo MRI. The spinal cord MRI will almost always confirm the presence of a lesion within the spinal cord, whereas the brain MRI may provide clues to other underlying causes, especially MS. If the disorder is advanced, MRI typically shows swelling of the spinal cord due to inflammation.

If an MRI is not possible (for example, if the patient has a pacemaker), physicians may consider other diagnostic tests such as computed tomography (CT) of the spine with or without myelography, which involves injecting a dye into the sac that surrounds the spinal cord. The patient is then tilted up and down to let the dye flow around and outline the spinal cord while X-rays are taken.

If MRI doesn't detect spinal cord compression, a spinal tap (lumbar puncture or LP) is done to obtain a sample of cerebrospinal fluid (CSF). The fluid will look to exclude infections and to look for markers of diseases such as MS. If ATM is present, the number of certain leukocytes (white blood cells) and the protein level in the CFS is increased.

Blood tests may be performed to rule out various disorders such as systemic lupus erythematosus, HIV infection, vitamin B12 deficiency, and many others A blood test for NMO, called NMO-IgG, is also necessary.

If testing and examination doesn't suggest a specific cause for the condition, the diagnosis is presumed to be idiopathic transverse myelitis (arises spontaneously or for which the cause is unknown). This is the case in 16 to 60% of people diagnosed with TM.

Treatment

If TM is caused by another disorder, that disorder is treated.

As with many disorders of the spinal cord, no effective cure currently exists for people with TM. Treatments are designed to reduce spinal cord inflammation and manage and alleviate symptoms. Doctors will often prescribe anti-inflammatory corticosteroid therapy soon after the diagnosis is made in order to decrease inflammation and hopefully improve the chances and speed of neurological recovery.

Although no clinical trials have investigated whether corticosteroids alter the course of TM, these drugs often are prescribed to reduce immune system activity because of the suspected autoimmune mechanisms involved in the disorder.

In severe cases that don't appear to respond to corticosteroid treatment, other therapies such as plasma exchange or drug therapies may be used to try to salvage neurological function.

General painkillers may be prescribed for any pain the patient may have. And bed rest is often recommended during the initial days and weeks after onset of the disorder.

Therapy For Loss of Function

Commonly experienced permanent neurological deficits resulting from TM may include severe weakness, spasticity (painful muscle stiffness or contractions), or paralysis; incontinence; and chronic pain. Such deficits can substantially interfere with a person's ability to carry out everyday activities such as bathing, dressing, and performing household tasks.

Many forms of long-term rehabilitative therapy are available for people who have permanent disabilities resulting from TM. Rehabilitative therapy teaches people strategies for carrying out activities in new ways in order to overcome, circumvent, or compensate for permanent disabilities.

Today, most rehabilitation programs attempt to address the emotional dimensions along with the physical problems resulting from permanent disability. Patients typically consult with a range of rehabilitation specialists, who may include physiatrists (physicians specializing in physical medicine and rehabilitation), physical therapists, occupational therapists, vocational therapists, and mental health care professionals.

Prognosis

Recovery from TM usually begins within 2 to 12 weeks of the onset of symptoms and may continue for up to 2 years (and in some cases longer). However, if there is no improvement within the first 3 to 6 months, complete recovery is unlikely.

Historic data shows about one-third of those affected with TM experience good or full recovery from their symptoms; they regain the ability to walk normally and experience minimal urinary or bowel effects and paresthesias. Another one-third experience only fair recovery and are left with significant deficits such as spastic gait, sensory dysfunction, and prominent urinary urgency or incontinence. The remaining one-third experience no recovery at all, remaining wheelchair-bound or bedridden with marked dependence on others for basic functions of daily living.

Unfortunately, making predictions about individual cases is difficult. Aggressive acute treatment and physical therapy have been shown to improve outcomes. However, research has shown that a rapid onset of symptoms generally results in poorer recovery outcomes.

The majority of people with this disorder experience only one episode although in rare cases recurrent or relapsing TM does occur. Some patients recover completely, then experience a relapse. Others begin to recover, then suffer worsening of symptoms before recovery continues.

In all cases of TM, physicians will evaluate possible underlying causes such as MS, NMO, or systemic lupus erythematosus since most people with these underlying conditions can experience a relapse and should be treated with preventative therapies. The purpose of such therapies is to reduce the chance of future relapses. Occasionally, the disorder recurs in people with MS or lupus. MS eventually develops in about 10 to 20% of people who have TM with no identified cause.