SHIN-JOE YEHLI-KAI TSAISUNG-CHUN TANGJIANN-SHING JENG2020-03-052020-03-0520141028-768Xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84901358409&partnerID=40&md5=1e381f83303cfddde97a1515fa4c2663https://scholars.lib.ntu.edu.tw/handle/123456789/470142Purpose: Hashimoto's encephalopathy (HE) is an autoimmune-mediated encephalopathy with various manifestations. Pupil size change has never been previously reported as a presentation of HE. Case Report: A 65-year-old woman without previous known thyroid disease presented with acute onset of drowsiness and blurred vision. Neurologically, she was drowsy and had bilateral pinpoint-sized pupils without a light reflex, which probably indicated a bilateral pontine lesion. Brain MRI showed two tiny infarctions at the left midbrain and left thalamus, but did not show a pontine lesion, and demonstrated patent vertebral/basilar arteries. Electroencephalography showed intermittent diffuse slowing. She had an elevated protein level (123 mg/dl) in cerebrospinal fluid without pleocytosis. Of note, she had elevated serum levels of anti-TG antibody (282 IU/mL) and anti-TPO antibody (117 IU/mL). Her symptoms improved spontaneously including gradually normalization of her pupil size in 3 days and clear consciousness in 6 days; therefore, corticosteroid was not administered. Conclusion: This case illustrates that physicians should be aware of the treatable condition of HE as a possible diagnosis in patients with bilateral pinpoint pupils and drowsiness but without corresponding MRI lesions.[SDGs]SDG3corticosteroid; thyroglobulin; aged; article; basilar artery; brain infarction; case report; cerebrospinal fluid; consciousness; diffusion weighted imaging; drowsiness; electroencephalogram; electroencephalography; female; Hashimoto encephalopathy; human; mesencephalon; neuroimaging; nuclear magnetic resonance imaging; pupil; thalamus; thyroglobulin blood level; thyroid disease; vertebral artery; brain disease; Cerebral Infarction; complication; differential diagnosis; Hashimoto disease; miosis; pathology; pons; sleep stage; Aged; Brain Diseases; Cerebral Infarction; Diagnosis, Differential; Female; Hashimoto Disease; Humans; Magnetic Resonance Imaging; Miosis; Pons; Sleep Stagesjournal article248332112-s2.0-84901358409