<p><strong>Background and Objectives</strong></p><p>Hashimoto's encephalopathy (HE) known as Steroid Responsive Encephalopathy associated with Autoimmune Thyroditis (SREAT) is a rare nervous system disease. HE was originally described by Brain, et. al. in 1966, however its cause still remains unknown after about 40 years. Autoimmune vasculitis of CNS, brain edema, and anti-thyroid antibodies are considered some of the etiologies for HE. It is certain that HE is an autoimmune disease and not a thyroid system disease. HE patients may or may not have goiter.</p><p>Some of the most common neurological manifestations of HE include: Confusion with altered consciousness, seizures, myoloclonus, and cognitive problems. Presence of high titers of anti-thyroid antibodies in blood serum and CSF of HE patients is considered the most common laboratory test for diagnosis of HE. EEG abnormalities such as diffuse slowing and atypical tri-phasic brain waves are the most common findings in about ¾ HE patients. Brain CT-Scan is normal in majority of HE patients. Global or local hypo perfusion may be seen in SPECT scanning of the brain. MRI findings are abnormal in about 40% of HE patients.</p><p>Patients with sub acute or acute onset of confusion, seizure, myoloclonus, stroke-like episodes and amnesia whose laboratory serum and CSF tests indicate presence of high titers of anti- thyroid antibodies should be considered for having HE. Vascular myelopathies, CJD, HSP, Myelinoclastic disease like PML, SSPE, ADE, MS and DNL are some of the differential diagnosis of HE.</p><p>Adrenal corticosteroids are the first line treatment for HE. Recurrent or steroid resistant HE cases may be treated by addition of other immunosuppressant drugs such as  Azathioprine, Cyclophosphamide, or Methotrexate to the 1^st line therapy.</p>