A Challenging Diagnosis of Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis (SREAT) in a Systemic Lupus Erythematosus (SLE) Patient With Hashimoto Encephalopathy (HE): A Case Report.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare condition that can present with multiple neurological and psychiatric manifestations. SREAT diagnosis poses a challenge due to the nature of its nonspecific symptomatology and its overlap with numerous autoimmune, metabolic, infectious, and neuropsychiatric disorders. It is associated with elevated anti-thyroid antibodies, occurs in correspondence with autoimmune thyroiditis, and shows great response to corticosteroid treatment. We present the case of a 27-year-old female patient with a complex medical history including systemic lupus erythematosus (SLE) and autoimmune thyroiditis. She presented to the hospital with bizarre behavior, psychosis, and confusion. Urine toxicology screen and septic workup were negative. Neuropsychiatric SLE (NPSLE) was high on the list of differential diagnosis but was excluded as the patient's previous lupus flares demonstrated an upward trend in anti-double-stranded deoxyribonucleic acid antibody (anti-dsDNA Ab) titers and low complement levels and leukocyte counts which were not present during this admission. Her cerebrospinal fluid (CSF) analysis was unremarkable except for higher-than-normal immunoglobulin G4 (IgG4) levels. Brain magnetic resonance imaging (MRI) was normal, and magnetic resonance angiography (MRA)/magnetic resonance venography (MRV) studies were unremarkable. Serum anti-thyroid antibodies were elevated which led to the consideration of Hashimoto encephalopathy (HE). SREAT diagnosis was made, and she made a remarkable recovery with the commencement of high-dose steroids slowly tapered over the course of weeks. Post-discharge outpatient visits showed back-to-baseline neurological and psychiatric status. It is important to note that both SREAT and NPSLE are rare diagnoses. They both overlap in many areas including their similar presentation, the lack of confirmatory tests, the diagnostic challenges, and their excellent response to steroids.