Introduction:
Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare autoimmune disorder affecting the central nervous system, characterized by a spectrum of neurological and psychiatric symptoms.

Aim:
This case study aims to highlight the diagnostic challenges and the successful management of SREAT syndrome in a young woman with autoimmune thyroiditis.

Case study:
A 21-year-old woman with documented Hashimoto's thyroiditis and polycystic ovary syndrome was admitted to the Clinic of Neurology following a 5-minute tonic seizure and subsequent confusion state lasting several hours. Initial brain MRI showed no abnormalities, and EEG revealed generalized slowness. Comprehensive laboratory assessments, including a complete blood count, biochemical analysis, and electrolyte panels, all yielded normal results. Further investigation revealed a significantly elevated anti-thyroid peroxidase antibody (anti-TPO) titer exceeding 1000 IU/mL. The suspicion of SREAT syndrome was considered. Pulse therapy with methylprednisolone was associated with rapid recovery. The patient was discharged from the hospital with an oral corticosteroid tapering regimen.

Results and discussion:
The administration of pulse therapy with methylprednisolone resulted in a rapid and very good response in the patient, evidenced by the resolution of seizure activity and improvement in confusion. Laboratory investigations, particularly the markedly elevated anti-TPO titer, supported the diagnosis of SREAT syndrome. The subsequent management with an oral corticosteroid tapering regimen maintained the patient's clinical stability.

Conclusions:
This case highlights the importance of considering autoimmune encephalopathy in patients with a history of autoimmune thyroiditis presenting with neurological and psychiatric symptoms. Further research is warranted to better understand the underlying pathomechanisms.