Transverse myelitis

Overview

Transverse myelitis is a neurological condition in which the spinal cord is inflamed. The inflammation damages nerve fibers, and causes them to lose their myelin coating leading to decreased electrical conductivity in the central nervous system. Transverse implies that the inflammation extends across the entire width of the spinal cord. Partial transverse myelitis and partial myelitis are terms used to define inflammation of the spinal cord that affects part of the width of the spinal cord.

Symptoms

There are disturbances in sensory nerves and motor nerves and dysfunction of the autonomic nervous system at the level of the lesion or below. Therefore, the signs and symptoms depend on the area of spine involved:

  • Cervical: If the upper cervical cord is involved, all four limbs may be involved and there is risk of respiratory paralysis (cervical nerve segments C3, 4, 5 innervate the abdominal diaphragm). Lesions of the lower cervical (C5–T1) region will cause a combination of upper and lower motor neuron signs in the upper limbs, and exclusively upper motor neuron signs in the lower limbs. Cervical lesions account for about 20% of cases.
  • Thoracic: A lesion of the thoracic spinal cord (T1–12) will produce upper motor neuron signs in the lower limbs, presenting as a spastic diplegia. This is the most common location of the lesion, and therefore most individuals will have weakness of the lower limbs.
  • Lumbar: A lesion of the lower part of the spinal cord (L1–S5) often produces a combination of upper and lower motor neuron signs in the lower limbs. Lumbar lesions account for about 10% of cases.

Symptoms include weakness and numbness of the limbs, deficits in sensation and motor skills, dysfunctional sphincter activities, and dysfunction of the autonomic nervous system. Symptoms typically develop over the course of hours or days and may progress after weeks. Sensory symptoms of transverse myelitis may include a sensation of pins and needles traveling up from the feet. Back pain can occur at the level of the inflamed segment of the spinal cord. The degree and type of sensory loss will depend upon the extent of the involvement of the various sensory tracts, but there is often a "sensory level" (at the sensory segmental level of the spinal cord below which sensation to pain or light touch is impaired).[citation needed] Motor weakness occurs due to involvement of the pyramidal tracts and mainly affects the muscles that flex the legs and extend the arms. Involvement of the autonomic nervous system is common and frequently leads to impaired function of the bladder and bowel and can also lead to episodes of high blood pressure. Bladder paralysis often occurs and urinary retention may be an early manifestation.

Causes

Transverse myelitis is a heterogeneous condition, that is, there are several identified causes. Sometimes the term Transverse myelitis spectrum disorders is used. It is rare for the condition to have no identifiable cause. When it appears along neuromyelitis optica, it is considered to be caused by NMO-IgG autoimmunity, and when appears in multiple sclerosis cases, it is considered to be produced by the same underlying condition that produces the lesions. In some cases, the disease is presumed to be caused by viral infections such as cytomegalovirus (CMV) and has also been associated with spinal cord injuries, immune reactions, schistosomiasis and insufficient blood flow through spinal cord vessels. Acute myelitis accounts for 4 to 5 percent of all cases of neuroborreliosis.

Transverse myelitis is associated with:

  • Bacterial Infections - Mycoplasma pneumoniae, Lyme disease.
  • Viral Infections - herpes simplex, herpes zoster, cytomegalovirus, Epstein-Barr virus, HIV/AIDS.
  • Vaccinations. Rarely, transverse myelitis has been reported to develop several days to a few months after vaccination. Between 1970 and 2009 there were 37 reported cases worldwide of transverse myelitis developing soon after vaccination (e.g. against hepatitis B, measles-mumps-rubella, diphtheria-tetanus-pertussis and others).
  • Multiple sclerosis
  • Paraneoplastic syndromes
  • Vascular etiology

Prevention

A Third of transverse myelitis cases would be prevented, if upper respiratory tract infections could be avoided. That's why, influenza vaccination is a prophylactic measure for transverse myelitis.

Diagnosis

Diagnostic criteria

In 2002 the Transverse Myelitis Consortium Working Group proposed the following diagnostic criteria for acute transverse myelitis:

Inclusion criteria:  

  • Motor, sensory or autonomic dysfunction attributable to spinal cord
  • Signs and symptoms on both sides of the body (not necessarily symmetrical)
  • Clearly defined sensory level
  • Signs of inflammation (pleocytosis of the cerebrospinal fluid, or elevated immunoglobulin G, or evidence of inflammation on gadolinium-enhanced MRI)
  • Peak of the condition occurs 4 hours to 21 days after onset

Exclusion criteria

  • Irradiation of the spine (e.g., radiotherapy) in the last 10 years
  • Evidence of thrombosis of the anterior spinal artery
  • Evidence of extra-axial compression on neuroimaging
  • Evidence of arteriovenous malformation (abnormal flow voids on surface of spine)
  • Evidence of connective tissue disease, e.g. sarcoidosis, Behçet's disease, Sjögren's syndrome, systemic lupus erythematosus or mixed connective tissue disease
  • Evidence of optic neuritis (diagnostic of neuromyelitis optica)
  • Evidence of infection (syphilis, Lyme disease, Human immunodeficiency virus, Human T-lymphotropic virus 1, mycoplasma, Herpes simplex virus, Varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, Human herpesvirus 6 or enteroviruses)
  • Evidence of multiple sclerosis (abnormalities detected on MRI and presence of oligoclonal antibodies in CSF)

Investigations

From the signs and symptoms it may be very difficult to distinguish acute transverse myelitis from these conditions and it is almost invariably necessary to perform an emergency magnetic resonance imaging (MRI) scan or computerized tomographic (CT) myelogram. Before doing this, routine x-rays are taken of the entire spine, mainly to detect signs of metastatic disease of the vertebrae, that would imply direct extension into the epidural space and compression of the spinal cord. Often, such bony lesions are absent and it is only the MRI or CT that discloses the presence or absence of a compressive lesion.

Typically individuals who develop transverse myelitis are transferred to a neurologist or neurosurgeon who can urgently investigate the patient in hospital. Before arranging this transfer, the physician should be certain that breathing is not affected, particularly in high spinal cord lesions. If there is any evidence of this, methods of respiratory assistance must be on hand before and during the transfer procedure. The patient should also be catheterized to test for and, if necessary, drain an over-distended bladder. A lumbar puncture can be performed after the MRI or at the time of CT myelography. Steroids are often given in high doses when symptoms begin with the hope that the degree of inflammation and swelling of the spinal cord will be lessened, but whether this is truly effective is still debated.

Lyme disease serology is indicated in patients with transverse myelitis keeping in mind that dissociation in Lyme antibody titers between the blood and the CSF is possible.



Prognosis

Recovery from transverse myelitis is variable between individuals and also depends on the underlying cause. Some patients begin to recover between weeks 2 and 12 following onset and may continue to improve for up to 2 years. Other patients may never show signs of recovery. However, if treated early, some patients experience complete or near complete recovery. Treatment options also vary according to the underlying cause and one treatment option in some cases is plasmapheresis.

The prognosis for significant recovery from acute transverse myelitis is poor in approximately 66% of the cases; that is, significant long-term disability will remain. Approximately 2% of these patients will, in later months or years, show lesions in other parts of the central nervous system, indicating, in retrospect, that this was a first attack of multiple sclerosis.

Treatment

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.