An Intriguing Case of Delirium: Recognizing Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis

Steroid-responsive encephalopathy, also known as Hashimoto's encephalopathy, is an uncommon autoimmune neuroendocrine disorder linked to thyroiditis. It presents a variable range of clinical symptoms, making it challenging to diagnose. SREAT (steroid-responsive encephalopathy associated with autoimmune thyroiditis) is considered a diagnosis of exclusion. Diagnosing SREAT poses a challenge as its symptoms can overlap with those of acute conditions such as encephalitis and meningitis, as well as various autoimmune disorders and issues related to substance toxicity and abuse, all of which must be ruled out prior to establishing a definitive diagnosis and starting treatment. However, high anti-TPO antibodies (anti-thyroid peroxidase) in serum and rarely in the CSF favor the diagnosis of the condition. Although rare, Hashimoto's encephalopathy should be considered when managing cases of unexplained encephalopathy. Treatment of choice in these sets of patients includes high-dose corticosteroid therapy. We present a case of Hashimoto's encephalopathy in a middle-aged woman who arrived at our emergency department with altered mental status and facio-brachial seizures. After excluding various potential causes of acute encephalopathy, a diagnosis of SREAT was made. Testing of serum and cerebrospinal fluid (CSF) indicated the presence of anti-thyroid peroxidase (anti-TPO) antibodies, which is uncommon in CSF. Following intravenous steroid therapy, the patient experienced substantial improvement, reinforcing the diagnosis.