Spontaneous Unilateral Carotid Dissection: A Case Report of a Rare Complication in a Patient With Graves' Disease.

Carotid artery dissection (CAD) is a recognized cause of ischemic stroke (IS) in young adults. At the same time, hyperthyroidism, particularly in the context of thyroid storm (TS), can also lead to IS through mechanisms related and unrelated to atrial fibrillation (AF). However, the coexistence of CAD and thyrotoxicosis is extremely rare. We report the case of a 45-year-old woman with Graves' disease (GD) who presented with TS, developing IS secondary to left CAD. The patient had a history of poorly controlled hyperthyroidism despite being on methimazole and beta-blocker therapy. Upon admission, she presented with fever, diarrhea, tremor, and palpitations. Physical examination revealed bilateral exophthalmos, goiter, and AF. Thyroid function tests confirmed TS, and treatment was initiated with antithyroid drugs, beta-blockers, glucocorticoids, and plasma exchange. Three days later, she developed focal neurological symptoms, and imaging studies revealed multiple ischemic lesions in the left middle cerebral artery territory. Further investigation confirmed left internal CAD, with no evidence of trauma or other underlying conditions to explain the dissection, leading to the conclusion that GD was the likely cause. The patient underwent thyroidectomy with subsequent clinical improvement, and she was discharged in good condition with long-term anticoagulation due to the presence of AF. This case highlights a rare association between GD and CAD, emphasizing the importance of considering CAD in patients with thyrotoxicosis who present with unexplained focal neurological symptoms. Early recognition and management of TS and CAD can improve clinical outcomes.