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Friday, December 04, 2020

What is transverse myelitis?

The mysterious inflammatory paralysis that struck AstraZeneca's volunteers is still poorly understood

W hen two subjects in AstraZeneca's COVID-19 vaccine clinical trial were diagnosed with transverse myelitis [1], many people wondered what it was. Even a physician of my acquaintance was confused about it, thinking incorrectly that it was a type of Guillain-Barré syndrome or GBS. It is an easy mistake to make: GBS is a also a rare paralytic complication of viral diseases. Both are inflammatory syndromes, but they are quite different.

Myelitis is a general term for inflammation of the spinal cord. It is not a disease, but a descriptive term. As the table below shows, there are many types of myelitis that differ in the part of the spinal cord that is affected.

Types of myelitis

 Name    Distribution    Notes  
Poliomyelitis Gray matter 'polio' means gray matter, i.e. the cell bodies
Leukomyelitis White matter 'leuko' means white matter, or myelinated axons
Transverse myelitis Entire cross sectional area
Longitudinally extensive myelopathy Vertically widespread and diffuse Autoantibodies may be involved
Meningomyelitis Meninges The three membranes that envelop the brain and spinal cord
Meningoradiculitis Meninges and root Roots are where the spinal nerves emerge
Pachymeningitis Spinal dura The outermost of the three meninges, a tough membrane
Epidural spinal abscess Epidural space Accumulation of infected material outside the dura
If viewing on a cell phone, drag table left or right to scroll.

Myelitis can be caused by viruses (the main one being poliovirus, but also Coxsackie A and B, Japanese encephalitis, herpes zoster, HIV-AIDS, HTLV, rabies, and West Nile virus). Sometimes these viral illnesses are benign and the paralysis is insignificant, though West Nile virus can cause a severe and persistent flaccid poliomyelitis.

There are several case reports of patients getting transverse myelitis after COVID-19.[2,3,4] The implication from the vast number of causes, including systemic lupus erythematosus, is of an inflammatory reaction or an autoimmune disorder triggered by something else. In the rare cases in which a vaccine is responsible, it has been suggested that some other common denominator, such as an adjuvant, might actually be responsible.[5]

AstraZeneca claimed that their first myelitis patient had undiagnosed multiple sclerosis and that their vaccine, which consists of a monkey adenovirus that shares a gene with SARS-CoV-2, is not responsible. Indeed, there are only two reports in the medical literature of acute transverse myelitis after adenovirus infection[6,7]. The appearance of a second case makes MS seem unlikely, but the cases seem to have been forgotten in the excitement and the confusion about their accidental finding that a lower dose worked better.

HIV myelopathy is somewhat unique. Spinal cord disease is often overlooked in HIV patients due to the multitude of other problems faced by these patients. In HIV patients, myelitis is typified by sensory ataxia (loss of sensation) and limb weakness. The white matter of the thoracic region of the spinal cord gets 'ballooning' caused by vacuoles in the myelin sheaths of the long tracts which connect the spinal cord to the rest of the CNS.

Myelitis can also be caused by bacterial, fungal, or parasitic diseases such as Lyme disease, tuberculosis myelitis, and syphilis. A similar condition is called neuromyelitis optica.


Contrary to popular belief, paralytic poliomyelitis is not a muscle disease, but an infection of the spinal cord. Sometimes polio causes a symmetrical paralysis of the muscles of the lower limbs and trunk resembling GBS. It can also cause a more serious condition called bulbar paralysis, which means paralysis of muscles innervated by the lower brainstem, including muscles of the jaw, face, tongue, pharynx, and larynx. Patients with a neurodegenerative condition called bulbar palsy have difficulty eating and with speech and ultimately with respiration and eventually die of aspiration pneumonia or exhaustion due to lack of food, called inanition.

Of more relevance to us, myelitis can also be caused by a noninfectious inflammation such as multiple sclerosis, antibodies against aquaporin (the water channel in cells) or antibodies against phospholipids (which make up the cell membrane), and, rarely, vaccines (though it's dangerous to say this due to the current hysteria about antivaxxers).


How could a vaccine cause myelitis? Myelitis from a virus or, much more rarely, a vaccine, is called a postvaccinal myelitide. Occasionally the brain is involved, in which case it is called acute disseminated encephalomyelitis or ADEM. These are all inflammatory disorders. The patient has weakness and numbness in the feet and legs resembling a polyneuropathy like GBS, which ascend over the next few days to the trunk. Unlike myelitis, a polyneuropathy like GBS is always symmetrical. A Babinski sign (a simple test given by a doctor) can distinguish myelitis from a polyneuropathy.[8]

Typically, as with GBS, a patient with myelitis had a respiratory disease within the previous two weeks. However, many cases occur without a known infection. Doctors often prescribe corticosteroids, i.v. immune globulin, or plasma exchange. Although 50% of the patients are completely paraplegic with some degree of bladder and bowel dysfunction[9], they usually improve within 3 to 6 months, though it is said[9] that up to 33% remain permanently disabled. Some sources suggest is that permanent disability means that the patient actually has multiple sclerosis, which can present similar symptoms.[8]

1.,,, Warning: animated ads

2. Baghbanian SM, Namazi F. Post COVID-19 longitudinally extensive transverse myelitis (LETM)-a case report. Acta Neurol Belg. 2020 Sep 18:1. doi: 10.1007/s13760-020-01497-x. PMID: 32948995; PMCID: PMC7500496.

3. Sarma D, Bilello LA. A Case Report of Acute Transverse Myelitis Following Novel Coronavirus Infection. Clin Pract Cases Emerg Med. 2020 Aug;4(3):321–323. doi: 10.5811/cpcem.2020.5.47937. PMID: 32926676; PMCID: PMC7434287.

4. Zachariadis A, Tulbu A, Strambo D, Dumoulin A, Di Virgilio G. Transverse myelitis related to COVID-19 infection. J Neurol. 2020 Dec;267(12):3459-3461. doi: 10.1007/s00415-020-09997-9. PMID: 32601756; PMCID: PMC7322383.

5. Agmon-Levin N, Kivity S, Szyper-Kravitz M, Shoenfeld Y. Transverse myelitis and vaccines: a multi-analysis. Lupus. 2009 Nov;18(13):1198–204. doi: 10.1177/0961203309345730. PMID: 19880568. Paywalled.

6. Breteau G, Stojkovic T, De Seze J, Gauvrit J, Pruvo J, Vermersch P. Myélite à adénovirus et Epstein-Barr virus: deux étiologies rares au profil identique [Adenovirus myelitis and Epstein-Barr myelitis: two unusual viral causes with similar presentations]. Rev Neurol (Paris). 2000 Sep;156(8–9):786–789. French. PMID: 10992125.

7. Linssen WH, Gabreëls FJ, Wevers RA. Infective acute transverse myelopathy. Report of two cases. Neuropediatrics. 1991 May;22(2):107–109. doi: 10.1055/s-2008-1071427. PMID: 1713310.

8. Some of the above is from Ropper AH, Samuels MA, Klein JP, Prasad S (eds.), Adams and Victor's Principles of Neurology, 11th ed, McGraw-Hill 2019

9. Simone CG, Emmady PD. Transverse Myelitis. 2020 Aug 10. In: StatPearls PMID: 32644728. Paywalled.

dec 04 2020, 6:31 am

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