Clinical Letter A Stroke Mimic: Anti-MOG Antibody-Associated Disorder Presenting as Acute Hemiparesis Michelle S. Tutmaher, DO a , Denise F. Chen, MD b , Jamika Hallman-Cooper, MD c , Philip J. Holt, MD a , Bryan Philbrook, MD c , Grace Y. Gombolay, MD c, * a Department of Pediatrics and Neurology, Emory University School of Medicine, Atlanta, Georgia b Department of Neurology, Emory University School of Medicine, Atlanta, Georgia c Division of Neurology, Department of Pediatrics, Pediatric Institute: Emory University/Children’s Healthcare of Atlanta, Atlanta, Georgia article info Article history: Received 6 December 2019 Accepted 29 February 2020 Available online xxx Background Demyelinating, inflammatory, and autoimmune conditions have been implicated as pediatric stroke mimics. 1 Anti-myelin oligo- dendrocyte glycoprotein-associated disorder (MOG-AD) has not yet been identified as a pediatric stroke mimic. MOG-AD is a distinct entity with varying clinical demyelinating diseases due to anti- MOG antibodies (MOG-ab). 2,3 Here we describe a patient who presented with acute-onset hemiparesis and respiratory failure with positive MOG-ab. Patient Presentation This 11-year-old previously healthy girl presented within one hour of developing sudden worsening of headache, acute-onset dysarthria, right central facial palsy, and right hemiparesis, con- cerning for an acute stroke. These acute symptoms were preceded by two days of intermittent headache and dizziness without fevers. On presentation, Glasgow Coma Scale score was 7, prompting intubation, and NIH Stroke Scale score was 31 for an intubated patient with flaccid weakness of the right arm and leg with mini- mal nonpurposeful movement of the left arm and leg. Urgent noncontrast head computed tomography and computed tomographic angiography were negative. Limited magnetic reso- nance imaging (MRI) of the brain showed normal diffusion- weighted imaging and normal magnetic resonance angiography. Complete blood count, chemistries, and toxicology screening were negative. She was admitted to the pediatric intensive care unit and placed on continuous video electroencephalography, which demonstrated focal slowing over the left hemisphere without epileptiform activity (Fig 1). MRI of the brain with contrast on hospital day (HD) one demonstrated leptomeningeal enhancement in the left frontal and parietal regions with associated mild cortical edema without diffusion restriction, optic neuritis, or other demyelinating lesions (Fig 2). Cerebrospinal fluid (CSF) studies revealed 8 white blood cells/mL (56% neutrophils), 1 red blood cell/mL, glucose 68 mg/dL, and protein 28 mg/dL. Negative CSF studies included cultures, herpes simplex virus polymerase chain reaction (PCR), varicella zoster virus PCR, enterovirus PCR, an arbovirus panel, Mycoplasma, Bartonella, cytomegalovirus, and Epstein-Barr virus antibodies, and human immunodeficiency virus antigen/antibodies. Serum and CSF autoimmune encephalopathy panels (at Mayo Clinic) were unreemarkable. Serum studies including antinuclear antibodies and anti-double-stranded DNA antibodies, angiotensin-converting enzyme, C3, C4, anti-thyroid peroxidase, thyroglobulin antibody, von Willebrand factor, anti- cardiolipin antibodies, and coagulation profile were also negative. However, serum MOG-ab was positive at 1:40. Her strength recovered within 24 hours of presentation without immunotherapy or steroids. She remained encephalopathic with confusion and mild anomic aphasia and intermittently febrile for the next eight days. Consequently, on HD six she was empirically Funding sources: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. * Communications should be addressed to: Dr. Gombolay; Division of Neurology; Department of Pediatrics; Pediatric Institute: Emory University/Children’s Health- care of Atlanta; 1400 Tullie Road NE; Atlanta, GA 30329. E-mail address: ggombol@emory.edu (G.Y. Gombolay). Contents lists available at ScienceDirect Pediatric Neurology journal homepage: www.elsevier.com/locate/pnu https://doi.org/10.1016/j.pediatrneurol.2020.02.009 0887-8994/© 2020 Elsevier Inc. All rights reserved. Pediatric Neurology xxx (xxxx) xxx Please cite this article as: Tutmaher MS et al., A Stroke Mimic: Anti-MOG Antibody-Associated Disorder Presenting as Acute Hemiparesis, Pediatric Neurology, https://doi.org/10.1016/j.pediatrneurol.2020.02.009