Transverse myelitis (TM) is a rare inflammatory disease causing injury to the spinal cord with varying degrees of weakness, sensory alterations, and autonomic dysfunction (the part of the nervous system that controls involuntary activity, such as the heart, breathing, the digestive system, and reflexes). The first cases of acute myelitis were described in 1882 and were attributed to vascular lesions and acute inflammatory events. In England between 1922 and 1923 more than 200 postvaccinial cases were noted as complications of the smallpox and rabies vaccines. Later reports revealed that TM was post-infectious in nature, and agents including measles, rubella and mycoplasma were directly isolated from patient’s spinal fluid. The term “acute transverse myelitis” was first used by an English neurologist in 1948 to describe a case of rapidly progressive paraparesis with a thoracic sensory level, occurring as a postinfectious complication of pneumonia. The Transverse Myelitis Consortium Working Group delineated diagnostic criteria for disease-associated TM and idiopathic TM along with a framework to differentiate TM from non-inflammatory myelopathies in 2002.
TM has a conservatively estimated incidence of between 1 and 8 new cases per million per year, or approximately 1400 new cases each year. Although this disease affects people of all ages, with a range of six months to 88 years, there are bimodal peaks between the ages of 10 to 19 years and 30 to 39 years. In addition, approximately 25% of cases are in children. There is no gender or familial association with TM. In 75-90% of cases TM is monophasic, yet a small percentage experience recurrent disease especially if there is a predisposing underlying illness.