Encephalopathy of Autoimmune Origin: Steroid-Responsive Encephalopathy With Associated Thyroiditis

Our objective is to highlight the importance of identifying symptoms of steroid-responsive encephalopathy with associated thyroiditis (SREAT), especially in the setting of intermittent cognitive dysfunction, and to inform that SREAT can develop even in patients with a history of partial thyroidectomies.

We present a case of a 51-year-old woman with a long-standing history of hypothyroidism presenting with acute onset myoclonus, involuntary tremors, fatigue, malaise, and palpitations for two weeks, with intermittent lapses in cognitive function. The patient's workup is completely within normal limits, including her cognition, except for elevated thyroid stimulating hormone levels and markedly elevated levels of antithyroid peroxidase antibodies, despite the fact that she previously had a partial thyroidectomy.

SREAT is an autoimmune condition characterized by cognitive dysfunction, elevated thyroid autoantibodies, and therapeutic response to corticosteroids. SREAT is primarily considered a diagnosis of exclusion. A crucial feature is the hallmark of significant improvement in symptoms when glucocorticoids are administered. There is a significant correlation between patients with elevated antithyroid peroxidase antibodies and new-onset SREAT. Although total thyroidectomy has been reported as a definitive treatment of SREAT, response to corticosteroids is the "sine qua non" in diagnosing this condition.

Hashimoto's thyroiditis can lead to a rare complication called SREAT, presenting with various neurologic symptoms. Prompt glucocorticoid treatment is vital, and a positive response confirms the diagnosis. Total thyroidectomy may be necessary for definitive SREAT treatment. More research is needed for alternate treatments and an understanding of the pathophysiology of SREAT.