Ayers T, Lopez A, Lee A, et al. - Researchers characterized the clinical, radiologic, laboratory, and epidemiologic findings of patients aged ≤ 21 years with acute flaccid myelitis (AFM), a neurologic condition characterized by flaccid limb weakness. Individuals meeting the acute flaccid limb weakness clinical case requirements from January 1, 2015, through December 31, 2017, were listed as either confirmed (spinal cord gray matter lesions on MRI) or probable (white blood cell count > 5 cells per mm³ in CSF). Of the 305 identified individuals from 43 states, 193 were confirmed and 25 were probable. An antecedent respiratory or febrile illness with a median of 5 days (interquartile range: 2 to 7 days) before limb weakness was reported in 79%. AFM surveillance data, including enteroviruses, suggested viral etiology. Further research is underway to better describe this unusual condition's etiology, pathogenesis, and risk factors.