The exact cause of transverse myelitis and extensive damage to nerve fibers of the spinal cord is unknown in many cases. Cases in which a cause cannot be identified are called idiopathic. However, looking for a cause is important, as some will change treatment decisions.
The discovery of circulating antibodies to the proteins aquaporin-4 and anti-myelin oligodendrocyte point to a definite cause in some individuals with transverse myelitis. Antibodies are proteins produced by cells of the immune system that bind to bacteria, viruses, and foreign chemicals to prevent them from harming the body. In autoimmune disorders, antibodies incorrectly bind to normal body proteins. Aquaporin-4 is a key protein that carries water through the cell membrane of neural cells. The myelin oligodendrocyte glycoprotein sits on the outer layer of myelin.
A number of conditions appear to cause transverse myelitis, including:
Immune system disorders. These disorders appear to play an important role in causing damage to the spinal cord. Such disorders are:
- aquaporin-4 autoantibody associated neuromyelitis optica
- multiple sclerosis
- post-infectious or post-vaccine autoimmune phenomenon, in which the body’s immune system mistakenly
- Attacks the body’s own tissue while responding to the infection or, less commonly, a vaccine
- an abnormal immune response to an underlying cancer that damages the nervous system; or
- other antibody-mediated conditions that are still being discovered.
- Viral infections. It is often difficult to know whether direct viral infection or a post-infectious response to the infection causes the transverse myelitis. Associated viruses include herpes viruses such as varicella zoster (the virus that causes chickenpox and shingles), herpes simplex, cytomegalovirus, and Epstein-Barr; flaviviruses such as West Nile and Zika; influenza, echovirus, hepatitis B, mumps, measles, and rubella.
- Bacterial infections such as syphilis, tuberculosis, actinomyces, pertussis, tetanus, diphtheria, and Lyme disease. Bacterial skin infections, middle-ear infections, campylobacter jejuni gastroenteritis, and mycoplasma bacterial pneumonia have also been associated with the condition.
- Fungal infections in the spinal cord, including Aspergillus, Blastomyces, Coccidioides, and Cryptococcus.
Parasities, including Toxoplasmosis, Cysticercosis, Shistosomiasis, and Angtiostrongyloides.
- Other inflammatory disorders that can affect the spinal cord, such as sarcoidosis, systemic lupus erythematosus, Sjogren’s syndrome, mixed connective tissue disease, scleroderma, and Bechet’s syndrome.
Vascular disorders such as arteriovenous malformation, dural arterial-venous fistula, intra spinal cavernous malformations, or disk embolism.
In some people, transverse myelitis represents the first symptom of an autoimmune or immune-mediated disease such as multiple sclerosis or neuromyelitis optica. (Multiple sclerosis, or MS, is disease that causes distinctive lesions, or plaques, that primarily affect parts of the brain, spinal cord, and optic nerve—the nerve that carries information from the eye to the brain.
Neuromyelitis optica, or NMO, is an autoimmune disease of the central nervous system that predominantly affects the optic nerves and spinal cord.) ”Partial” myelitis—affecting only a portion of the cord cross-section—is more characteristic of multiple sclerosis. Neuromyelitis optica is much more likely as an underlying condition when the myelitis is “complete” (causing severe paralysis and numbness on both sides of the spinal cord).