Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) presenting with pure cerebellar ataxia

Background: Myoclonus and tremor are common movement disorder phenomenologies in steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT). Pure ataxia without encephalopathy has rarely been reported. Case report: We report 21- and 40-year-old females who presented with subacute pure ataxia without encephalopathy. After immunotherapies, both exhibited initial improvement of ataxia, and subsequently remained in plateau phase. Discussion: This treatable disorder should be added to the differential diagnoses of progressive cerebellar ataxia, and anti-thyroid peroxidase and antithyroglobulin should be considered as part of the workup. It is crucial not to misdiagnose SREAT presenting with pure cerebellar ataxia as degenerative or spinocerebellar ataxia.