A Case of Steroid-Responsive Encephalopathy

Hashimoto's encephalopathy (HE), also known as steroid-responsive encephalopathy, is associated with autoimmune-mediated thyroiditis. Onset is typically gradual often with evolution over the course of months. Characteristic symptoms include impaired concentration and memory, delusions, hallucinations, personality changes, incoordination, tremor, hemiparesis, seizures, and speech difficulties. Diagnosis is predicated upon discovery of elevated anti-thyroid antibodies, specifically anti-thyroid peroxidase (TPO) or anti-M antibodies. Some patients may also present with subclinical hypothyroidism but many are euthyroid. Of note, neither thyroid function tests or antibody titers correlate with disease severity. Other common laboratory findings include elevations in sedimentation rate, liver enzymes, and cerebrospinal fluid (CSF) protein. Radiological work-up, including cerebral angiography, is often normal. Successful treatment includes administration of steroids and/or intravenous immunoglobulin (IVIg) or plasmapheresis. We describe a case of a 74-year-old male who presented for evaluation of abrupt onset confusion ultimately determined to be a consequence of autoimmune-mediated thyroiditis.