AFM is defined by the acute onset of flaccid weakness in the setting of a longitudinal lesion of the spinal cord, usually in the setting of a febrile or respiratory illness.  There is a risk for rapid progression to respiratory distress, particularly for patients with upper extremity or bulbar involvement, thus early recognition and close monitoring are essential to patient safety.  Patients given an alternate diagnosis in the acute care setting are at risk for decompensation at home.

To delineate diagnoses assigned to patients at the first presentation of acute flaccid myelitis (AFM).

Retrospective review of medical records to identify the diagnosis at initial presentation in patients cared for at Boston Children’s Hospital, Children’s Hospital of Philadelphia, Children’s Hospital of Wisconsin, or Mount Sinai Kravis Children’s Hospital. All cases met clinical and spinal cord imaging criteria for AFM.

We identified a total of 40 patients with a diagnosis of AFM.  A total of 23 patients (58%) were initially given an alternate diagnosis.  Of these, 14 (61%) were discharged home from the acute care setting and later returned, requiring admission. Multiple visits prior to admission were common.  Common alternate diagnoses included injury (including brachial plexus injury), toxic synovitis, non-specific viral illness, and functional neurological disorder.  Of the total 40 patients with AFM at our centers, 9 (22.5%) required respiratory support.

AFM is a serious emerging condition that is associated with significant morbidity.  Misdiagnosis in the acute care setting is common.  Given the high percentage of patients with AFM requiring respiratory support, a misdiagnosis with discharge home increases the chance of respiratory decompensation occurring in a non-clinical setting.  Efforts focused on the education of first line providers are needed to mitigate this risk for increased morbidity and mortality.