Transverse myelitis is an inflammation of the full width of the spinal cord that disrupts communication to the muscles, resulting in pain, weakness, and muscle paralysis.
Description
The symptoms of transverse myelitis are due to damage and/or destruction of the myelin sheath, the fatty white covering of nerve fibers that serves both to insulate the nerve fibers and to speed nervous conduction along them. Areas of missing myelin and areas of scarring along the affected nerves result in slowed or disrupted nervous conduction and muscle dysfunction.
Transverse myelitis may have a gradual onset or a remarkably quick onset. Symptoms of transverse myelitis may reach their peak within 24 hours of onset for some patients (considered the hyperacute form of the condition). Other patients experience a more gradual increase in symptom severity, with peak deficits occurring days (acute form of transverse myelitis) to weeks (subacute form of transverse myelitis) after the initial symptoms first presented. Patients with the quicker onset form and who experience more severe initial symptoms tend to have more complications and a greater likelihood of permanent disability.
Transverse myelitis often occurs in people who are recovering from a recent viral illness, including chickenpox, herpes simplex, cytomegalovirus, Epstein-Barr, influenza, and measles. When this association is present, the condition often follows the more sudden hyperacute course.
Demographics
In the United States, there are only about 4.6 cases of transverse myelitis per million people per year. In the Unites States, about 1,400 people a year develop transverse myelitis; about 33,000 people in the United States have disabilities due to transverse myelitis. Individuals of all ages can be affected; reports have been made of patients ranging from the age of six months to 88 years. The peak ages appear to be 10-19 years and 30-39 years.
About 30-60% of all cases of transverse myelitis occur in individuals who have just recovered (within the previous 8 weeks) from a relatively minor viral infection. Recent vaccination is another risk factor for transverse myelitis. Other individuals at higher risk for transverse myelitis include patients with preexisting autoimmune diseases (such as multiple sclerosis, systemic lupus erythematosus, or Devic's disease); patients with recent histories of infections such as Lyme disease, tuberculosis, or syphilis; and intravenous drug abusers who inject heroine and/or amphetamines.
Causes and symptoms
Although the specific mechanism of transverse myelitis has not been delineated, the basic cause is thought to be an autoimmune response. Under normal conditions, the immune system reacts to the presence of a viral or bacterial illness by producing a variety of immune cells designed to attack the invading viruses or bacteria. Unfortunately, in the case of transverse myelitis, the immune cells mistake the body's own tissues as foreign, and attack those tissues as well. These errant immune cells are called autoantibodies; that is, antibodies that actually attack the body's own tissues.
Symptoms of transverse myelitis can develop over several hours, days, or weeks. The types of symptoms and their severity are dependent on the area of the spinal cord affected. When the transverse myelitis occurs in the neck, the arms and legs will be affected; when the transverse myelitis occurs lower in the back, only the legs will be affected.
Symptoms of transverse myelitis often begin with back pain, headache, achy muscles, flu-like symptoms, and stiff neck. Over hours or days, symptoms expand to include loss of sensation, numbness, dysesthesia (sensations of burning, lightning flashes of pain, prickly pinpoints), muscle weakness, partial or complete paralysis, and impaired bladder and bowel function. Symptoms of weakness and then paralysis usually begin in the feet, ascending over time to the legs, and then to the trunk and arms when the lesion is in the neck. Symptoms are bilateral, meaning that they affect both sides of the body simultaneously. Over time, muscles become increasingly tight and spastic, further limiting mobility. When the muscles of respiration are affected, breathing can be compromised.
Diagnosis
Diagnosis involves meeting specific symptom criteria, as well as demonstrating spinal cord involvement with MRI scanning and examination of cerebrospinal fluid. Symptom criteria include the evolution of symptoms peaking over four hours to 21 days, with symptoms clearly traceable to spinal cord dysfunction, and including muscle weakness or paralysis and sensory defects such as numbness occurring on both sides of the body. The presence of a spinal cord tumor or another condition that is exerting pressure on the spinal cord, vitamin B12 deficiency, or a history of radiation therapy to or cyclophosphamide injection into the spinal cord excludes the possibility of a diagnosis of transverse myelitis.
Treatment team
The mainstay of the treatment team for patients with transverse myelitis will be a neurologist. A rheumatologist, specializing in autoimmune illness, may also be consulted. In order to regain maximum function, a physiatrist (a physician specializing in rehabilitation medicine) may be required, as well as the services of both physical and occupational therapists.
Treatment
Treatment is aimed at calming the immune response that caused the spinal cord injury in the first place. To this end, high doses of intravenous and then oral steroids are the first-line treatments for transverse myelitis. In severe cases of transverse myelitis, the very potent immunosupressant cyclophosphamide may be administered. In patients with moderately severe transverse myelitis unimproved by five to seven days of steroid treatment, a procedure called plasma exchange may be utilized. This procedure involves removing blood from the patient, and separating it into the blood cells and the plasma (fluid). The blood cells are then mixed into a synthetic plasma replacement solution and returned to the patient. Because the immune cells are in the plasma, this effectively removes the damaging immune cells from the body, hopefully quelling the myelin destruction.
Treatments to reverse the process involved in transverse myelitis should be attempted for about six months from the onset of the condition. After that point, treatment efforts should be shifted to effective rehabilitation.
Pain and other dysesthesias (uncomfortable sensations, such as burning, pins-and-needles, or electric shock sensations) are treated with a variety of medications, such as gabapentin, carbamazepine, nortriptyline, or tramadol. Another treatment for pain and dysesthesias is transcutaneous electrical nerve stimulation, called TENS therapy. This involves the use of a device that stimulates the painful area with a small electrical pulse, which seems to disrupt the painful sensation.
Because constipation and urinary retention are frequent problems in the patient with transverse myelitis, medications may be necessary to treat these problems. Oxybutinin, hyoscyamine, tolterodine, and propantheline can treat some of the bladder problems common to transverse myelitis patients. When urinary retention is an issue, sacral nerve stimulation may help the patient avoid repeated bladder catheterizations. Dulcolax, senekot, and bisacodyl can help improve constipation.
Tight, spastic muscles may improve with baclofen, tizanidine, or diazepam. When these medications are given orally, they sometimes result in untenable side effects.
Recovery and rehabilitation
Rehabilitation has both short-and long-term components. Even in the earliest stages of the condition, passive exercises should be performed. Passive exercises involve a physical therapist putting a particular muscle group or joint through range of motion and strengthening exercise, even when the patient cannot assist in its movement. During the recovery phase, the patient should be given progressive exercises to improve strength and range of motion, and to attempt to regain mobility. Physical therapists can also be helpful with pain management, using such techniques as heat and/or cold application, nerve stimulation, ultrasound, and massage. Physical therapy may also be helpful to retrain muscles necessary for improved bladder and bowel control and relief of constipation and urinary retention. Occupational therapists can help the patient relearn old skills for accomplishing the activities of daily living, or strategize new techniques that take into account the patient's disabilities.
Braces or assistive devices such as walkers, wheelchairs, crutches, or canes may be necessary during rehabilitation or permanently.
Prognosis
The area on the spinal cord affected by transverse myelitis will determine the individual's level of functioning. The higher-up the lesion, the greater the disability. High cervical lesions will require complete care; as lesions drop lower and lower in the cervical, thoracic, or lumbar region, the chance to participate in self-care or even to ambulate increases.
Recovery from transverse myelitis seems to follow the law of thirds: about a third of all patients make a full recovery from their level of functioning at the condition's peak, a third make a partial recovery, and a third make no recovery at all. Most patients make a good or even a complete recovery within one to three months of the onset of their symptoms. Patients who have not begun to improve by month three after symptom onset usually will not accomplish a complete recovery from their disability. Factors that do not bode well include abrupt onset of symptoms, prominent pain upon onset, and severe disability and deficit at the peak of the condition.
BOOKS
Aminoff, Michael J. "Inflammatory disorders affecting the spinal cord." In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000.
Schneider, Deborah Ross. "Transverse Myelitis." In Essentials of Physical Medicine and Rehabilitation, 1st ed., edited by Walter R. Frontera. Philadelphia: Hanley and Belfus, 2002.
PERIODICALS
Transverse Myelitis Consortium Working Group. "Proposed diagnostic criteria and nosology of acute transverse myelitis." In Neurology 59, no. 4 (27 August 2002): 499–505
