Childhood Acute Flaccid Myelitis, Including the First Confirmed Cases of Enterovirus D68 Myelitis, in Singapore and Southeast Asia

Aim: We report the epidemiology, treatment and outcomes of acute flaccid myelitis (AFM), including the first two cases of enterovirus (EV) D68 myelitis, in Singapore.

Methods: Retrospective observational study from a paediatric hospital in Singapore, from January 2012 to December 2022. Clinical, laboratory, neuroimaging and outcome data were analysed.

Results: Eight patients were identified (all male). Median age at presentation was 3 (interquartile range (IQR) 2.2-10.0) years. Seven (87.5%) patients were clustered in two time periods (July 2018-January 2019 and April-August 2022). Presenting features were a preceding febrile respiratory illness (n = 6) or hand-foot-and-mouth disease (n = 2), upper limb weakness (n = 5, 62.5%) and neurogenic bladder (3, 37.5%), while the spinal cord lesions were predominantly in the cervical region (7, 87.5%). Five (62.5%) and six (75.0%) patients had elevated cerebrospinal fluid (CSF) white cells (median 7.5/mm (IQR 2.8-40.3)) and protein (median 0.6 g/L (IQR 0.4-0.7)), respectively. CSF was negative for pathogens. Two (50%) of four patients with EV detected in respiratory/rectal swabs had EVD68 (2022 cluster). All received intravenous methylprednisolone, six (75%) had additional intravenous immunoglobulin and either plasma exchange therapy (n = 1) or intravenous tocilizumab (n = 1). Median modified Rankin Scale (mRS) at acute illness was 4 (IQR grades 3-5), with an improvement (median 2 (IQR 1.8-2.3) mRS grades) on follow-up (median duration 3.7 (IQR 1.4-4.1) years). One patient (12.5%) had a full recovery and seven (87.5%) have moderate disability (mRS 2-3).

Conclusion: Disability risk in AFM is high despite aggressive immunotherapy. We report the first two confirmed cases of EV D68 AFM in Singapore and Southeast Asia.