Spontaneous Remission in Hashimoto's Encephalopathy: A Report of a Rare Case

Hashimoto's encephalopathy is a condition usually diagnosed by exclusion. Although its exact aetiology remains unknown, extensive case reports and studies suggest that autoimmunity contributes to its development with the presence of antithyroid antibodies. While there is no pathognomonic sign of Hashimoto's encephalopathy, it manifests with encephalopathic symptoms such as confusion, delirium, and even seizures. This case report discusses a 35-year-old woman with a notable history of hypothyroidism who presented with seizures preceded by a day of episodes of confusion and unresponsiveness. Upon admission, she was transferred to our intensive care unit. Extensive investigations revealed elevated thyroid peroxidase antibodies and an electroencephalogram (EEG) showing wave patterns characteristic of an encephalitic process. The patient met the diagnostic criteria for Hashimoto's encephalopathy after excluding other potential causes. The patient's symptoms were well controlled with levetiracetam and phenytoin, and her thyroid dysfunction was treated with levothyroxine, resulting in subsequent improvement. The primary treatment for Hashimoto's encephalopathy is corticosteroids. Literature highlights corticosteroids as the main treatment for Hashimoto's encephalopathy, although alternative options such as intravenous immunoglobulin (IVIG) and plasma exchange have also been used. Nonetheless, despite its rarity, there have been reported instances of spontaneous remission. Our case similarly illustrates this possibility, as we discuss how a young female patient who meets the criteria for Hashimoto's encephalopathy experienced complete recovery through spontaneous remission. Clinicians should therefore be aware of the potential for spontaneous remission when dealing with Hashimoto's encephalopathy.