title: Hashimoto encephalopathy: syndrome or myth?
abstract: BACKGROUND
  Hashimoto encephalopathy has been described as a syndrome of encephalopathy and high serum antithyroid antibody concentrations that is responsive to glucocorticoid therapy, but these could be chance associations.
  
  
  OBJECTIVE
  To study a patient with Hashimoto encephalopathy and to review the literature to determine whether Hashimoto encephalopathy is an identifiable syndrome.
  
  
  METHODS
  We searched the MEDLINE database to June 2002 for "Hashimoto" or "autoimmune thyroiditis" and "encephalopathy" and examined all identified articles and articles referenced therein, including all languages. We included all patients with noninfectious encephalopathy (clouding of consciousness and impaired cognitive function) and high serum antithyroid antibody concentrations. We excluded patients if they did not meet these inclusion criteria or if their symptoms could be explained by another neurologic disorder. We recorded clinical features and the results of imaging, electroencephalographic, thyroid function, and cerebrospinal fluid studies.
  
  
  RESULTS
  We identified 85 patients (69 women and 16 men; mean age, 44 years) with encephalopathy and high serum antithyroid antibody concentrations. Among these patients, 23 (27%) had strokelike signs, 56 (66%) had seizures, 32 (38%) had psychosis, 66 (78%) had a high cerebrospinal fluid protein concentration, and 80 (98%) of 82 had abnormal electroencephalographic findings. Thyroid function varied from overt hypothyroidism to overt hyperthyroidism; the most common abnormality was subclinical hypothyroidism (30 patients [35%]). Among patients treated with glucocorticoids, 66 (96%) improved.
  
  
  CONCLUSIONS
  The combination of encephalopathy, high serum antithyroid antibody concentrations, and responsiveness to glucocorticoid therapy seems unlikely to be due to chance. However, there is no evidence of a pathogenic role for the antibodies, which are probably markers of some other autoimmune disorder affecting the brain.
authors.affiliation: Department of Neurology, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Ji Y
authors.initials: JY
authors.lastname: Chong
authors.forename: Lewis P
authors.initials: LP
authors.lastname: Rowland
authors.forename: Robert D
authors.initials: RD
authors.lastname: Utiger
mesh_terms: D002556:Cerebrospinal Fluid Proteins / Q000032:analysis; D003937:Diagnosis, Differential; D004569:Electroencephalography; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D008875:Middle Aged; D012640:Seizures / Q000209:etiology*; D020521:Stroke / Q000209:etiology*; D013577:Syndrome; D013967:Thyroiditis, Autoimmune / Q000473:pathology* / Q000628:therapy
chemical_list: D002556:Cerebrospinal Fluid Proteins; D005938:Glucocorticoids