Steroid-responsive encephalopathy associated with autoimmune thyroiditis.

Hashimoto encephalopathy or steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare condition associated with rapidly progressive dementia, stroke-like symptoms, psychosis and positive antithyroid antibodies. In this case report, a woman in her 80s with hypothyroidism and no other medically relevant history presented with a 2-week complaint of progressive hallucinations, short-term memory loss and paranoia. Eventually hospitalised, her hospital course was complicated by severe hospital-acquired delirium, which clouded the clinical picture; however, initial workup revealed an elevated thyroglobulin antibody and thyroid peroxidase, both highly specific for SREAT. A 3-day course of high-dose methylprednisolone (1 g/day) was administered, which revealed marked improvement in patient symptoms. Definitive treatment included a 13-week oral prednisone taper and outpatient follow-up with neurology and primary care. In cases of new onset neuropsychiatric symptoms in geriatric populations, SREAT is a reversible, must-not-miss diagnosis, when treated with systemic steroids.