Inflammation in the spinal cord can cause the myelin and axon to be damaged resulting in symptoms such as paralysis and sensory loss.

The similarity of the words reflects that the combining form myel(o)- has multiple (homonymous) senses referring to bone marrow or the spinal cord.

Most myelitis manifests fast progression in muscle weakness or paralysis starting with the legs and then arms with varying degrees of severity.

Also symptoms generally include paresthesia which is a sensation of tickling, tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect.

Immunoglobulins directed against the α-isoform of glial fibrillary acidic protein (GFAP-IgG) predicted a special meningoencephalomyelitis termed autoimmune GFAP Astrocytopathy[10] that later was found also to be able to appear as a myelitis.

In order to establish a diagnosis of myelitis, one has to localize the spinal cord level, and exclude cerebral and neuromuscular diseases.

Full spine MRI is warranted, especially with acute onset myelitis, to evaluate for structural lesions that may require surgical intervention, or disseminated disease.

Lumbar puncture is important for the diagnosis of acute myelitis when a tumoral process, inflammatory or infectious cause are suspected, or the MRI is normal or non-specific.