A Rare Case of Symptomatic Carotid Stenosis Caused by Mechanical Stimulation by Thyroid Cartilage and Frequent Swimming.

ABSTRACT

BACKGROUND: Bony structures around the carotid artery such as the styloid process and hyoid bone can cause dissection, compression, plaque formation, and plaque rupture of the carotid artery. To the best of our knowledge, this case is the first finding of thyroid cartilage being the cause of a lesion corresponding to adjacent common carotid artery (CCA) atherosclerosis. CASE DESCRIPTION A 51-year-old man with a history of hypertension and dyslipidemia suddenly experienced right facial numbness and dysphasia while front crawl swimming, which he usually did 3 times weekly. Diffusion-weighted magnetic resonance imaging showed high intensity areas in the left frontal and parietal lobes. He was diagnosed with acute cerebral infarction and was administered with tissue plasminogen activator. Angiography of the left CCA revealed mild stenosis with an intravascular filling defect, and carotid duplex ultrasonography of the CCA on the second day after symptom onset showed plaque and intraluminal thrombus at the stenotic site. Plain and contrast-enhanced computed tomography showed that thyroid cartilage contacted the left CCA at the stenotic site, and the left CCA moved backward and forward with the thyroid cartilage during neck rotation. We determined that mechanical stimulation by the thyroid cartilage had induced the plaque during the frequent neck rotation that is a feature of front crawl swimming. CONCLUSIONS: Evaluation of anatomical interactions between the carotid artery and bony structures including the thyroid cartilage is important to ensure that appropriate treatment is selected to prevent further ischemia.