Evolving Features of Acute Flaccid Myelitis After COVID-19: A Four-Case Series

Acute flaccid myelitis (AFM) is a rare, polio-like illness typically affecting children, often preceded by a viral prodrome and characterized by asymmetric flaccid paralysis. The biennial pattern of AFM outbreaks was disrupted by the COVID-19 pandemic, potentially altering the timing and clinical characteristics of AFM. Here we describe four Center for Disease Control and Prevention-confirmed AFM cases after the pandemic onset to (1) explore evolving clinical features and (2) identify potential outcome predictors.

We retrospectively reviewed medical records of four patients meeting Center for Disease Control and Prevention AFM criteria. Data on demographics, presentation, investigations, treatments, and outcomes were analyzed.

All cases showed atypical features: two patients were outside the usual pediatric age range; three lacked a viral prodrome and had notable sensory symptoms; and one presented with symmetric weakness. All experienced bowel/bladder dysfunction, with persistent symptoms in two. Three had normal cerebrospinal fluid white cell counts. Spinal magnetic resonance imaging confirmed gray matter involvement in all, though findings did not correlate with disease severity. Electrodiagnostic studies (in two cases) confirmed severe motor neuron injury. Low vitamin D levels were noted in all patients tested. Enterovirus D68 was identified in two young Caucasian females, both of whom had favorable recoveries. Shorter hospital stays were associated with better functional outcomes.

These postpandemic AFM cases illustrate a broader, evolving clinical spectrum possibly influenced by pandemic-related environmental or immune factors. Magnetic resonance imaging was not predictive of severity, while electrodiagnostic studies were more informative. Vitamin D deficiency and certain demographic or viral factors may influence prognosis and merit further investigation in larger, multicenter studies.