What is acute transverse myelitis in children?

Acute transverse myelitis (ATM) is a potentially devastating immune-mediated disorder of the spinal cord that affects all ages. The onset is often unaccompanied by any identifiable cause, and although the results of immediate treatment may be effective in moderating the damage, long-term sequelae in children are common. Because of its rarity, the causes, optimal treatment, and outcomes for ATM in children are poorly known. Typical ATM is a monofocal and monophasic inflammatory disorder targeting primarily the spinal cord, resulting in motor, sensory, and autonomic dysfunction. Approximately 1400 new cases are diagnosed in the United States each year (1–8 per million inhabitants per year), resulting in a prevalence of around 34,000 people with residual disabilities related to ATM [1,2]. Only about 20% of these patients are diagnosed with ATM before the age of 18 years [3]. Similarly, the recent population-based Canadian Paediatric Surveillance Program evaluated the incidence of ATM at 0.2 per 100,000 children [4]. In this study, incidence did not differ according to season, the female:male ratio was 0.81:1, and occurrence was similar whether ATM started before or after the age of 10 years [4]. When classified as a sub-group of acute disseminated encephalomyelitis (ADEM), ATM accounted for 30% of the topographic spectrum of central nervous system (CNS) involvements [5]. If only a single episode of ATM in childhood was considered, the prevalence was 10 times lower than for pediatric multiple sclerosis (MS).