Recurrent steroid-intolerant Hashimoto’s encephalopathy responsive to single-dose neonatal Fc receptor antagonist: a case report and literature review

BACKGROUND: Hashimoto’s encephalopathy (HE) is a rare, underdiagnosed, steroid-responsive autoimmune condition associated with thyroid autoimmunity. CASE PRESENTATION: An 83-year-old female patient was admitted to hospital displaying symptoms of subacute cognitive decline, dysarthria and myoclonus. She had a history of Hashimoto’s thyroiditis and diabetes. Given the patient’s age and comorbid diabetes, the potential risks associated with steroid treatment were considered excessive. She was given an 800 mg dose of efgartigimod-α, which swiftly improved her ambulatory stability and cognitive function. Approximately four weeks later, the patient exhibited a clinical relapse and underwent a subsequent treatment cycle with efgartigimod-α. Each treatment cycle significantly alleviated the patient’s symptoms. CONCLUSIONS: The report under consideration herein highlights the clinical presentation, diagnostic challenges, and therapeutic considerations of HE, emphasizing the potential role of Neonatal Fc receptor (FcRn) antagonists, such as efgartigimod-α, as an emerging treatment strategy. The repeated administration of FcRn antagonists has been posited as a potential therapeutic intervention for patients diagnosed with hormone-intolerant Hashimoto’s encephalopathy.