Renard D, Azakri S, Arquizan C, Swinnen B, Labauge P, Thijs V. Styloid and Hyoid Bone Proximity Is a Risk Factor for Cervical Carotid Artery Dissection. Stroke. 2013
Cervical carotid artery dissection (CAD) as a cause of stroke is commonly encountered in patients with history of neck trauma, chiropractor manipulation of neck and connective tissue disorder such as fibromuscular dysplasia. Some patients with cervical carotid artery dissection may have only history of projectile vomiting or violent coughing prior to the event and in a few patients a definite precipitating factor may not be identified. Renard and colleagues evaluated the role of anatomic factors such as the proximity of styloid and hyoid bone to the Internal Carotid Artery (ICA) in patients with CAD.
The authors performed a retrospective review of 88 CAD patients, 88 age and sex matched controls without dissection and 32 vertebral artery dissection patients. One rater blinded to clinical data and radiological reports evaluated the axial CTA images of the neck of these patients and measured the distance from the center of the ICA to the styloid and hyoid bone. They found that regardless of the side of the dissection patients with CAD had shorter styloid-ICA and hyoid-ICA distance compared to age and sex matched non dissection control group and vertebral artery dissection group. Among patients with CAD the styloid-ICA distance was significantly shorter on the side of dissection (ipsilateral) compared to the non dissection (contralateral) side. Similar comparison was not significant for the hyloid-ICA distance.
The findings of this study shed light on the possibility of external mechanical compression by bony structures on ICA as a potential cause of CAD. If these results are confirmed with larger studies then in the future styloid bone surgery may be a potential treatment option for patients with CAD to prevent further events.
If the workup for CAD reveals no identifiable precipitating cause, I would probably measure the styloid-ICA distance just for the fun of doing it though this would not change the clinical management. The mean ipsilateral styloid-ICA distance was 53.9 mm in patients with CAD in this study. Would you consider measuring the styloid ICA distance in similar patient population?