New Cluster of Acute Flaccid Myelitis in Western Pennsylvania Natan Cramer, MD; Neil Munjal, MD; Danielle Ware, DO; Sriram Ramgopal, MD; Dennis Simon, MD; Megan C. Freeman, MD, PhD; Marian G. Michaels, MD, MPH; Christopher Stem, MD; Kavita Thakkar, MD; John V. Williams, MD; Ashok Panigrahy, MD; Desiree N. W. Neville, MD; Sylvia Owusu-Ansah, MD, MPH* *Corresponding Author. E-mail: sylvia.owusuansah@chp.edu. Acute flaccid myelitis is a debilitating illness characterized by acute onset of limb weakness, with one or more spinal segments displaying magnetic resonance imaging–confirmed gray matter lesions. Since the first outbreak in 2014, tracking by the Centers for Disease Control and Prevention has demonstrated biennial epidemics in the United States, with a current outbreak occurring in 2018. The cases of 3 children with acute flaccid myelitis who were initially thought to have common nonneurologic diagnoses are presented. Emergency physicians need to be vigilant to recognize the subtleties of acute flaccid myelitis because the illness progression is rapid and therapy is nuanced. [Ann Emerg Med. 2019;-:1-6.] 0196-0644/$-see front matter Copyright © 2019 by the American College of Emergency Physicians. https://doi.org/10.1016/j.annemergmed.2019.01.024 INTRODUCTION Viral-mediated pathogenesis for acute flaccid myelitis has been suggested, given similarities to poliovirus, associations with enterovirus D68, and seasonal variation. 1,2 There have been a total of 440 cases recorded, with 116 in 2018 alone. 2 Acute flaccid myelitis typically begins with a constitutional prodrome and most patients present in early childhood. 1,3 Weakness develops and is often asymmetric, with one or more limbs involved. Diminished reflexes are appreciated. 1 The site most affected is the cervical spine. 1 Gray matter lesions are initially diffuse but become more localized to the anterior horn cells. Enhancement is observed in the minority of patients. 1,4 Cerebrospinal fluid pleocytosis is typical. 1 A high degree of suspicion is required to promptly identify cases of acute flaccid myelitis in patients with a constitutional prodrome, focal motor deficit, and decreased reflexes to prevent additional morbidity and establish early neurorehabilitative efforts. CASE REPORTS On September 28 to 30, 2018, 3 previously healthy immunized children younger than 5 years and from the Pittsburgh area presented with acute flaccid myelitis (Figure 1 and Table 1). Case 1 A 3-year-old boy presented to the emergency department (ED) with 3 days of fever, fatigue, and pharyngitis, and 24 hours of vomiting, with generalized weakness. Vital signs were notable for fever and tachycardia. The patient was unable to sit up but was able to move all extremities. He was mildly hypoglycemic but was noted to have improved strength after intravenous fluids. The patient was admitted with the assumption that the weakness was a result of sepsis, dehydration, and hypoglycemia. Within hours of admission, he was noted to have decreased spontaneous movements. Inpatient neurology consultation demonstrated weakness in all extremities (power grade 1/5 in the left upper extremity and 3/5 in all other extremities). There was no difference in proximal or distal muscle strength. Light touch sensation was intact. Deep tendon reflexes were 1þ throughout and symmetric. His examination worsened over 10 hours from admission to flaccid quadriplegia and respiratory failure, prompting emergency intubation. Magnetic resonance image (MRI) demonstrated increased T2 signal in the central gray matter of the cervical spine and thoracic spine (vertebrae levels 7 to 10), as well as the dorsal pons and midbrain. Because of initial concern for transverse myelitis, intravenous methylprednisolone (30 mg/kg) was administered. On further deliberation, acute flaccid myelitis was diagnosed and human intravenous immunoglobulin (2 g/kg) was administered 5 days after prodromal onset. Cerebrospinal fluid obtained after imaging and steroid administration was notable for a lymphocytic pleocytosis. He was transferred to inpatient rehabilitation on hospital day 9. At 2 weeks after transfer, he demonstrated minimal improvement in head control but otherwise continued to have severe functional motor impairment. Volume -, no. - : - 2019 Annals of Emergency Medicine 1 PEDIATRICS/CASE REPORT