Lupus myelitis causes inflammation of the spinal cord. It's a rare problem caused by the disease systemic lupus erythematosus (SLE). SLE is an autoimmune system disease. This means that the body's natural defense system (the immune system) attacks your body's healthy tissues instead of attacking only things like bacteria and viruses.
Lupus myelitis can become severe. It can occur at any time during the course of SLE, including as the first symptom or years after diagnosis.