Thyroid Steal Syndrome Secondary to Active Hyperthyroid State.

Thyroid steal syndrome (TSS) is a rare condition characterized by recurrent transient ischemic attack (TIA) that is found to be due to a large thyroid goiter or thyroid hormone derangement causing a diversion of blood flow from the cerebral circulation. Here we report a patient with a history of multiple TIAs thought initially to be due to intracranial arterial stenosis based on CT angiography (CTA) findings, but later found to be secondary to hyperthyroid state causing TSS. To our knowledge, this is the first-ever reported case of TSS secondary to hyperthyroidism and only the second case of TSS secondary to any thyroid hormone derangement.