To present a rare case of Steroid Responsive Encephalopathy Associated with Autoimmune Thyroiditis (SREAT) in a patient with bitemporal lobar hyperintensities.

A fifty-year-old female patient presented to the hospital for one month of progressive memory impairment and bilateral tonic-clonic seizures. Brain MRI demonstrated bilateral temporal lobe T2/FLAIR hyperintensities without contrast enhancement, initially concerning for encephalitis. CSF profile and viral studies, however, were normal. EEG demonstrated bitemporal delta slowing with focal left temporal electrographic seizures. Empiric high dose IV steroids were initiated. The patient was found to have a very elevated antithyroid peroxidase antibody levels with normal thyroid function studies. The remainder of her extensive laboratory work-up was negative. Her mentation dramatically improved with a course of IV steroids, thus confirming our suspicion for SREAT. She was ultimately discharged on a six-week oral steroid taper, however re-presented three months later with severe headaches. Repeat imaging demonstrated a new area of right temporal hyperintensity. Her symptoms improved after re-initiation of pulse dose steroids and she was thus discharged with an extensively prolonged steroid taper. The patient continues to do well and has returned to work as a registered nurse.