Carotid Dissection
Carotid dissection is a false channel in the wall of the carotid artery produced by a tear in the intima. The classic triad of symptoms is unilateral neck pain or headache, stroke or transient ischemic attack, and an incomplete Horner syndrome (miosis and ptosis without anhidrosis). Dissections can be spontaneous or traumatic, caused by shearing of the internal carotid artery between the C2 and C3 transverse processes during deceleration injuries such as car accidents, wrestling, or chiropractic maneuvers. The primary treatment of dissection is drug therapy. With warfarin anticoagulation (to an INR of 2.0-3.0), 60-85% of carotid dissections will heal in 3-6 months with complete or near-complete neurologic recovery. Recurrent dissection is estimated at 3% at 3 years and 12% at 10 years and most often involves a different cervical vessel, which justifies the use of long-term aspirin. Surgery (usually carotid interposition) or carotid stenting is indicated for persistent symptoms despite optimal drug therapy.

Carotid Body Tumors
The carotid body is a chemoreceptor derived from embryonic neural crest cells located at the carotid bifurcation. Carotid body tumors (also called paraganglionomas or chemodectomas) are rare and usually present as painless neck masses. Most of these tumors are slow growing and benign, but lymph node metastases have been reported.

If untreated, they are locally invasive; a large tumor may cause vagus or hypoglossal nerve deficit from mass effect or may encircle the internal carotid artery to the skull base. The tumor is hypervascular and splays the internal and external carotid arteries, giving it a classic angiographic appearance of a tumor blush in the center of a widened carotid bifurcation. Biopsy is contraindicated; diagnosis is made by CT angiography or MRA. Preoperative angiography for tumor embolization and test occlusion of the internal carotid artery may be considered for tumors over 4 cm in diameter. Using the same approach as for carotid endarterectomy, the tumor is resected from the carotid artery, with care to preserve the artery wall adventitia. Many small arteries arising from the external and internal carotid arteries supply the tumor and must be ligated individually. The incidence of cranial nerve injury with resection of large tumors approaches 40%. Prognosis after complete resection is excellent, with survival equal to that of age-matched controls and long-term recurrence of 6%.

Carotid Artery Aneurysms
Carotid aneurysms are much more common in the intracerebral than in the cervical portion of the carotid arteries. Most often, cervical aneurysms arise in the common carotid artery and are fusiform; these are associated with atherosclerosis. Traumatic aneurysms can be related to healing of an internal carotid dissection or to penetrating trauma. Mycotic aneurysms can be caused by staphylococcal, Escherichia coli, or tuberculous infections. Many other vasculitides are associated with carotid aneurysms, such as Behcet’s disease, Takayasu’s disease, fibromuscular dysplasia, and segmental arterial mediolysis. Anytime a mass in the neck is pulsatile, an aneurysm should be considered and diagnosis confirmed by angiography. Other symptoms include neck pain, cranial nerve dysfunction, and transient ischemic attack or stroke. Surgery should be considered for aneurysms resulting from penetrating trauma, aneurysms associated with neurologic deficit, mycotic aneurysms, and aneurysms over 2 cm in diameter. Primary repair of the artery may be accomplished for most penetrating injuries. Carotid resection and interposition grafting are performed for most other aneurysms.

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Kremer C et al: Carotid dissection with permanent and transient occlusion or severe stenosis: long term outcome. Neurology 2003;60:271.

Milhaud D et al: Occlusion due to a carotid artery dissection: a more severe disease than previously suggested. Arch Neurol 2002;59:557.