title: Acute Flaccid Myelitis of Unknown Etiology in California, 2012-2015.
abstract: OBJECTIVE
  There has been limited surveillance for acute flaccid paralysis in North America since the regional eradication of poliovirus. In 2012, the California Department of Public Health received several reports of acute flaccid paralysis cases of unknown etiology.
  
  
  OBJECTIVE
  To quantify disease incidence and identify potential etiologies of acute flaccid paralysis cases with evidence of spinal motor neuron injury.
  
  
  METHODS
  Case series of acute flaccid paralysis in patients with radiological or neurophysiological findings suggestive of spinal motor neuron involvement reported to the California Department of Public Health with symptom onset between June 2012 and July 2015. Patients meeting diagnostic criteria for other acute flaccid paralysis etiologies were excluded. Cerebrospinal fluid, serum samples, nasopharyngeal swab specimens, and stool specimens were submitted to the state laboratory for infectious agent testing.
  
  
  METHODS
  Case incidence and infectious agent association.
  
  
  RESULTS
  Fifty-nine cases were identified. Median age was 9 years (interquartile range [IQR], 4-14 years; 50 of the cases were younger than 21 years). Symptoms that preceded or were concurrent included respiratory or gastrointestinal illness (n = 54), fever (n = 47), and limb myalgia (n = 41). Fifty-six patients had T2 hyperintensity of spinal gray matter on magnetic resonance imaging and 43 patients had cerebrospinal fluid pleocytosis. During the course of the initial hospitalization, 42 patients received intravenous steroids; 43, intravenous immunoglobulin; and 13, plasma exchange; or a combination of these treatments. Among 45 patients with follow-up data, 38 had persistent weakness at a median follow-up of 9 months (IQR, 3-12 months). Two patients, both immunocompromised adults, died within 60 days of symptom onset. Enteroviruses were the most frequently detected pathogen in either nasopharynx swab specimens, stool specimens, serum samples (15 of 45 patients tested). No pathogens were isolated from the cerebrospinal fluid. The incidence of reported cases was significantly higher during a national enterovirus D68 outbreak occurring from August 2014 through January 2015 (0.16 cases per 100,000 person-years) compared with other monitoring periods (0.028 cases per 100,000 person-years; P <.001).
  
  
  CONCLUSIONS
  In this series of patients identified in California from June 2012 through July 2015, clinical manifestations indicated a rare but distinct syndrome of acute flaccid paralysis with evidence of spinal motor neuron involvement. The etiology remains undetermined, most patients were children and young adults, and motor weakness was prolonged.
authors.affiliation: Department of Neurology, Stanford University School of Medicine, Stanford, California2Division of Child Neurology, Lucile Packard Children's Hospital, Stanford, California.
authors.forename: Keith
authors.initials: K
authors.lastname: Van Haren
authors.affiliation: US Centers for Disease Control and Prevention, Atlanta, Georgia4Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond5Now with Metabiota, San Francisco, California.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ayscue
authors.affiliation: Department of Neurology, University of California, San Francisco7Department of Pediatrics, Benioff Children's Hospital, University of California, San Francisco.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Waubant
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Anna
authors.initials: A
authors.lastname: Clayton
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Heather
authors.initials: H
authors.lastname: Sheriff
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yagi
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Rose
authors.initials: R
authors.lastname: Glenn-Finer
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Tasha
authors.initials: T
authors.lastname: Padilla
authors.affiliation: Department of Neurology, University of California, San Francisco7Department of Pediatrics, Benioff Children's Hospital, University of California, San Francisco.
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Strober
authors.affiliation: Children's Hospital Los Angeles and University of Southern California, Los Angeles.
authors.forename: Grace
authors.initials: G
authors.lastname: Aldrovandi
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Debra A
authors.initials: DA
authors.lastname: Wadford
authors.affiliation: Departments of Laboratory Medicine and Medicine, Division of Infectious Diseases, University of California, San Francisco10University of California, San Francisco, Viral Diagnostics and Discovery Center, San Francisco.
authors.forename: Charles Y
authors.initials: CY
authors.lastname: Chiu
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Dongxiang
authors.initials: D
authors.lastname: Xia
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Harriman
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond.
authors.forename: James P
authors.initials: JP
authors.lastname: Watt
authors.affiliation: Center for Infectious Diseases, Division of Communicable Disease Control, California Department of Public Health, Richmond7Department of Pediatrics, Benioff Children's Hospital, University of California, San Francisco11Now with Department of Pediatrics, K.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Glaser
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004576:Electromyography; D005260:Female; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D015994:Incidence; D007275:Injections, Intravenous / Q000706:statistics & numerical data; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009046:Motor Neurons; D009123:Muscle Hypotonia / Q000134:cerebrospinal fluid / Q000453:epidemiology* / Q000628:therapy; D009187:Myelitis / Q000134:cerebrospinal fluid / Q000453:epidemiology* / Q000209:etiology / Q000628:therapy; D010951:Plasma Exchange / Q000706:statistics & numerical data; D020127:Recovery of Function; D012189:Retrospective Studies; D017678:Sex Distribution; D013256:Steroids / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D016756:Immunoglobulins, Intravenous; D013256:Steroids