Inclusion and exclusion criteria for the diagnosis of acute transverse myelitis (ATM), as a basis for multicenter clinical trials, are proposed by a Transverse Myelitis Consortium Working Group. Idiopathic ATM is distinguished from ATM secondary to known underlying disease. Inclusion diagnostic criteria are the following: bilateral signs and/or symptoms of spinal sensory, motor, or autonomic (sphincter) dysfunction; defined sensory level; MRI negative for extra-axial compression; CSF pleocytosis, elevated IgG index, or abnormal gadolinium enhancement indicative of spinal inflammation; progressive symptoms with nadir at 4 h to 21 d following onset. Exclusion criteria include : prior spinal irradiation; anterior spinal artery thrombosis; AV malformation; connective tissue disease (sarcoidosis, Behcet’s, SLE etc); CNS syphilis, Lyme disease, HIV, HSV, EBV, CMV, or other viral disease; MRI evidence of MS or ADEM; history of optic neuritis and Devic’s disease. A potential work-up for suspected ATM is outlined. Identification of known etiologies can lead to specific treatments whereas idiopathic ATM, that constitutes about 16% of cases, has no established therapy. 
COMMENT. With the current interest in revival of smallpox vaccination, this proposal for diagnosis of acute transverse myelitis is timely. More than 200 cases of postvaccinial encephalomyelitis were reported in England in 1922-3, a complication of smallpox and rabies vaccination (Rivers TM, 1929). The present proposal to distinguish idiopathic and secondary etiologies for ATV should clarify methods and results of therapy and prognosis.
Textbook descriptions of ATM mention pain in the back or extremities and sensory loss as the earliest symptoms. Two thirds have a history of recent infection (herpes, EBV, hepatitis B, influenza, measles, mumps, varicella), vaccinations, especially rabies, and with SLE. Pain is followed by progressive paraparesis, loss of sphincter tone, fever in 50%, and neck stiffness in one third. Flaccid weakness gradually changes to pyramidal tract signs, with hyperreflexia, clonus, and extensor responses. A sensory level (between T5-T10) affects primarily pain and temperature, and posterior columns are usually spared. CSF shows pleocytosis and an elevated protein in 50%, and neuroimaging is usually unremarkable. Prognosis is usually good, only 15% failing to show improvement. Therapy including steroids is of unproven benefit. (Menkes JH, 1981).