Myelitis is an affectation that occurs in the neuronal axons and usually causes important modifications of the electrical activity of these axons, as well as in the activity of the immune system.

There are two major types of myelitis that vary according to the cause, the severity of the damage, and the specific symptoms . We will now look at what each treats, what the main causes are and what the treatment is.

What is myelitis?

Myelitis is an inflammation of the spinal cord that can significantly affect the responses emitted from the brain to the rest of the body, and vice versa.

This is because this inflammation can cause a decrease in or significant damage to myelin, the lipid substance that coats the nerve axons. This substance has among its responsibilities to regulate the speed of conduction of electrical impulses between neurons, so an alteration of their functions produces changes in the activity of the same.

On the other hand, myelitis can be caused by infections derived from different viruses, bacteria, fungi and parasites . In these cases the spinal cord is affected by an immune system response that, instead of creating antibodies to counteract the viruses, reproduces the same virus causing the inflammation. It is therefore considered a type of autoimmune disease.

Two types of myelitis: their differences

Myelitis commonly occurs in a narrow region within the spinal cord. However, in some cases it can spread to other areas, generating different damages and symptoms . When it is a specific region, it is usually due to an infection, while when it extends to other areas, it is usually a process of multicausal myelin depletion.

Accordingly, two major types of myelitis are usually recognized: polio and transverse myelitis. Let’s look at their differences.

1. Poliomyelitis

Also called polio or infantile paralysis, it is a myelitis caused by viral infections . It usually affects the grey matter, which produces symptoms such as muscular paralysis (in many cases permanent, but not necessarily) and excessive tiredness.

In the case of the polio virus affecting the spine, common symptoms are leg paralysis. Mild symptoms include headaches, fever and pain in the extremities .

On the other hand, if the polio virus affects the bulbar region of the brain, the affected area is the white matter and the cranial nerves, resulting in paralysis of the muscles of the face and symptoms such as encephalitis, difficulty in breathing or in speaking and swallowing. Another way myelitis has been called when it affects the white matter is leukomyelitis, a condition related to similar diseases such as multiple sclerosis.

Finally, if the virus affects the bulb-spinal region and associated cranial nerves , it can cause paralysis of the diaphragm, inflammation of the lungs and impairment of heart function.

It is usually transmitted through infected fecal matter, which in turn can be found in contaminated food and water. Less often it is transmitted through saliva. A stool test, or a test for antibody activity in the blood, is used to diagnose it.

Polio can be prevented by a vaccine (polio vaccine). However, there is no definitive cure. Drug treatment consists of taking antibiotics , to prevent major infections, analgesics for pain control, and moderate exercise along with physical therapy and nutritious diets.

2. Transverse myelitis

Transverse myelitis is caused by a process of myelin reduction (demyelination) on the sides of the spinal cord. It is called “transverse” precisely because the inflammation spreads to these sides , although sometimes it can affect only one of them. In the latter case it is called “partial transverse myelitis”.

It usually causes symptoms such as excessive tiredness or weakness and numbness of the extremities, sometimes accompanied by headaches and muscle aches. It also causes changes in sensation and motor skills, urethral function and the anal sphincter. In some cases it also affects the autonomic nervous system, which can lead to episodes of hypertension.

This is a heterogeneous condition, the causes of which may be diverse. For example, it can be caused by infections, but also by disorders of the immune system, damage to nerve fibres and damage to myelin sheaths, which in turn can cause major changes in the conduction of electrical signals between neurons . The definite and underlying cause of the latter is so far unknown.

For the same reason there is no definitive cure. The treatment is usually symptomatic, that is, it tries to reduce each of the symptoms according to their particular nature. It may include physical therapy to recover some motor functions, as well as the use of support tools to replace or enhance these functions.

Bibliographic references:

  • Poliomyelitis (polio) World Health Organization. Recovered October 9, 2018. Available at
  • What is Transverse Myelitis? (2018). Neurology and Neurosurgery. Johns Hopkins Medicine. Recovered October 9, 2018. Available at