Three-Year Longitudinal Motor Function and Disability Level of Acute Flaccid Myelitis

Background: We summarize the long-term motor outcome and disability level in a cluster of pediatric patients with acute flaccid myelitis (AFM) associated with the enterovirus D68 outbreak in 2015. Methods: This is a nationwide follow-up questionnaire analysis study. Clinical data including the motor function (manual muscle strength test) and other neurological symptoms were collected at the acute (nadir), recovery (six months), and chronic (three years) stages. We use the Barthel index, which measures 10 variables describing activity of daily living and mobility to assess the disability level. Results: Clinical data of 33 patients with AFM (13 females, 20 males; median age = 4.1 years) were available. Among patients with tetraplegia or triplegia, paraplegia, and monoplegia at the acute stage, two of seven, four of thirteen, and two of thirteen exhibited complete recovery without paralysis; of those five of seven, eight of thirteen, and two of thirteen showed improvement with lesser limb involvement at the chronic stage, respectively. Nine patients (27%) demonstrated improvement at the recovery-to-chronic period. All six patients with positive isolation of enterovirus D68 from biological samples at the acute stage showed persistent motor deficits. Other neurological findings had better prognosis than motor weakness. Better Barthel index score at the chronic stage was observed (P < 0.001; median difference [95% confidence interval], 53 [40 to 63]), implying an improved disability level even in patients with persistent motor deficits. Conclusions: AFM has a high rate of persistent motor deficits showing one- to two-limb paralysis. Disability level of patients with AFM, however, generally improved at the three-year time point.