Acute flaccid myelitis: Long-term outcomes recorded in the CAPTURE study compared with paediatric transverse myelitis

Background Since 2014, the USA has documented three outbreaks of acute flaccid myelitis (AFM). Unique features and treatment responses of this myelitis variant have not been prospectively studied. This study prospectively measured outcomes in paediatric myelitis patients relative to treatments. Methods This was a prospective, multicentre, non-randomised, observational cohort study. The study duration was 5 years and the length of follow-up was 1 year. This study collected data from children and families in North America. Patients were enrolled at academic centres with expertise in myelitis or online via a web portal. Paediatric patients diagnosed with myelitis were eligible for enrolment in the study within 6 months of onset of symptoms. Patients were characterised as transverse myelitis (TM) or the AFM variant based on clinical and radiographic findings. Results The cohort of 90 patients included patients with AFM and TM. Of the 51 patients with AFM there was evidence of two clinically relevant patterns. This included a grey matter restricted form of AFM and a cohort with concomitant white matter that could explain lower extremity motor deficits in patients with lesions restricted to the cervical spine. The improvement in deficits with the use of corticosteroids was similar to what was observed in the TM cohort (p=0.97). Conclusions Clinicians should consider on a case by case basis the approach to therapy for AFM patients. Prospective controlled studies of long-term outcomes would be useful in this growing patient population.