Intrathoracic carotid bifurcation in Klippel-Feil syndrome.

Intrathoracic carotid bifurcation is rare with only five other cases reported. This anatomic variant with posteromedial origin of the internal carotid artery (ICA) appears to be part of the Klippel-Feil syndrome, a rare congenital defect characterized by fusion of the cervical vertebrae. Caution is advised when planning thoracic and cervical vascular procedures. Angiography carries higher risk of unintentional ICA catheterization due to the short common carotid artery length. The intrathoracic location of the carotid bifurcation makes endarterectomy difficult and patients may do better with carotid artery stenting. Ultrasound can be confusing in these patients and MRA may be preferable.