Since 2012, the polio-like illness acute flaccid myelitis (AFM) has occurred across several global regions and has primarily been reported in children. A review paper in the Lancet recently published an evidence-based overview of the cause, diagnosis, and management of this condition and labeled it as an emerging global public health concern.
In the paper, authors on behalf of the AFM working group noted that there appears to be a potential viral link to AFM cases. Currently, evidence supports non-polio enterovirus infection as a cause of AFM, particularly as the disease shares similar features to that of the viral infection. Many patients with AFM report febrile prodrome alongside respiratory symptoms during the days prior to muscle weakness onset.
Additionally, evidence links a causal association of AFM with enterovirus supported by the temporal and geographical associations between cases of AFM and enterovirus circulation. Review authors were unclear on the specific mechanisms behind viral infection leading to AFM, however, and this remains a critical topic for future investigation.
To date, there remains no single sensitive and specific test for AFM. Additionally, there is no uniform diagnostic criteria for the condition. The disease is typically presented in children at a median age of 6.3 years, and less than 15 percent of cases occur in adult patients. Diagnosis often includes the assessment of clinical, neuroimaging, and cerebrospinal fluid characteristics. Neurological symptoms, which occur between 1 to 10 days after the onset of infectious prodrome, are often accompanied by neck stiffness, headache, or fever recurrence.
Many patients experience significant residual disability and require long-term rehabilitation following the acute phase of the disease. Rehabilitation and long-term clinical care of patients with AFM include multidisciplinary inpatient rehabilitation, nerve and tendon transfer surgery, medium- to long-term rehabilitation, and long-term medical management. In long-term medical management, patients should continue on vaccination protocols detailed in national guidelines, should undergo neurology follow-up appointments, and receive specialist input regarding management of complications, long-term ventilatory support, or artificial nutrition.
The increasing incidence of AFM suggests that the condition is an emerging and significant global public health concern that requires additional research into its diagnosis and management. In addition, the authors of this review concluded that there is a need for “increased awareness of the presenting clinical features of AFM, allowing accurate case ascertainment to understand epidemiology and burden of disease, early recognition to allow prompt specimen collection and causal diagnosis, and early initiation of potential therapies.”
Murphy OC, Messacar K, Benson L, et al. Acute flaccid myelitis: cause, diagnosis, and management. Lancet. Published online December 21, 2020. doi:10.1016/S0140-6736(20)32723-9