The internal carotid artery supplies the anterior two-thirds of the cerebral hemispheres, the eye via the ophthalmic artery, and the pituitary gland. Unlike the external carotid which has many branches in the neck, the ICA has no branches in the neck — a clinically useful distinguishing feature during carotid endarterectomy. Atherosclerotic stenosis at the ICA origin is the leading cause of embolic ischaemic stroke, and carotid endarterectomy reduces stroke risk in symptomatic patients with greater than 70 percent stenosis.
| Origin | Bifurcation of the common carotid artery at C4 level |
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Carotid bifurcation atherosclerosis produces ipsilateral amaurosis fugax (transient monocular blindness from ophthalmic artery embolism) and contralateral hemispheric TIA or stroke symptoms. Carotid endarterectomy is indicated for symptomatic patients with 70 to 99 percent stenosis with a 10 percent absolute risk reduction in stroke over 2 years. ICA dissection from neck trauma or spontaneous (fibromuscular dysplasia) produces Horner syndrome, neck pain, pulsatile tinnitus, and stroke or TIA from intraluminal thrombus embolisation.
Atherosclerotic narrowing at the ICA origin producing embolic TIA and stroke treated with carotid endarterectomy in symptomatic patients with greater than 70 percent stenosis.
Intimal tear from trauma or fibromuscular dysplasia producing Horner syndrome, neck pain, and embolic stroke managed with anticoagulation or antiplatelet therapy.
