RESUMEN

Hashimoto's thyroiditis is an autoimmune thyroid disease characterized by lymphocytic infiltration and thyroid-specific autoantibodies. Hashimoto's encephalopathy, a rare entity associated with these antibodies, presents as a relapsing encephalopathy with neuropsychiatric manifestations and seizures. A 15-year-old girl, initially healthy, experienced a tonic-clonic seizure. Despite unremarkable initial assessments, she returned with generalized convulsive status epilepticus. Hashimoto's thyroiditis was suggested by elevated thyroid-stimulating hormone levels, low thyroxine levels, and high anti-thyroid antibodies, and was confirmed by ultrasound. Steroids were not used initially due to seizure cessation with anesthesia. Post-treatment with levothyroxine and antiepileptics, she was seizure-free at follow-up and eventually maintained solely on levothyroxine. Hashimoto's encephalopathy, characterized by diverse symptoms, often necessitates corticosteroids, immunoglobulins, and plasmapheresis, as traditional anti-seizure medications fail. Further research into its etiology and pathophysiology is essential. Consider Hashimoto's encephalopathy in unexplained seizures, especially with ineffective standard treatments. Pediatric diagnostic criteria need to be revisited.