ESPE Abstracts

Introduction: Hashimoto's autoimmune thyroiditis is the primary cause of acquired hypothyroidism, with encephalopathy being a rare complication, particularly in children. Early and accurate diagnosis is crucial, as appropriate treatment is usually successful, while untreated cases can result in permanent impairment.

Case presentation: A 17-year-old girl complained of numbness on the right side of her body and tongue, difficulty speaking, and sluggishness. Elevated levels of thyroid antibodies – 627.37 IU/mL (N 0–3.2), thyroid stimulating hormone – 275.69 mkIU/mL (N 0.35–5.5), and low levels of free thyroxine – 0.2 ng/dL (N 0.89–1.76) were detected. The brain MRI showed a non-specific lesion in the right juxtacortical area without contrast accumulation and a few lesions with haemosiderin depositions in the right of the pons. During hospitalization, the patient had generalized tonic-clonic seizures lasting up to a minute, along with focal onset motor seizures lasting about 30 seconds, with dyskinesia-like episodes in between the latter. An electroencephalogram showed moderate focal epileptiform activity in the left temporal area. Cerebrospinal fluid analysis for all tested antibodies for surface neuronal antigens was negative, while antibodies for the intracellular antigen Ri (anti-Ri) were detected; however, all other intracellular antigens tested were negative. The patient has been treated with levothyroxine (initial dose – 75 mcg/day, increased to 125 mcg/day), carbamazepine (initial dose – 200 mg/BID, increased to 400 mg/BID), intravenous immunoglobulin therapy (110 g over 5 days) and prednisolone (initial dose – 60 mg/day, decreased to 50 mg/day and tapered off until complete withdrawal).

Discussion: Despite extensive research, the exact cause of HE remains elusive, however, existing evidence suggests an autoimmune origin, possibly involving vasculitis or other inflammatory mechanisms. The clinical presentation of Hashimoto's encephalopathy (HE) encompasses a spectrum of variable and nonspecific manifestations, such as seizures, stroke-like episodes, cognitive decline, and neuropsychiatric symptoms. The diagnosis of HE typically requires fulfillment of 3 criteria: cognitive impairment, cerebrospinal fluid analysis negative for infectious aetiologies, and elevated levels of anti-thyroid antibodies in serum. These criteria, alongside a positive response to corticosteroid therapy, typically delineate the diagnosis of HE.

Conclusion: Encephalopathy is a rare complication of Hashimoto's autoimmune thyroiditis. This case underscores the significance of recognizing uncommon immune-mediated encephalopathies and conducting comprehensive tests to rule out alternative diagnoses.