Giant cell arteritis is a common form of systemic vasculopathy affecting patients older than 50 years. Although it typically involves the temporal, maxillary, and ophthalmic arteries, it can rarely affect the siphon of the internal carotid artery, sometimes producing bilateral stenosis.

CLINICAL MANIFESTATIONS

TIAs in patients with carotid artery disease usually precede stroke onset by a few days or months. TIAs caused by intra-arterial embolism from a carotid source are not stereotypical, and symptoms vary depending on which ICA branch is involved. In contrast, hemodynamic “limb-shaking” TIAs are often stereotypical and posturally related and are usually seen in patients with high-grade ICA stenosis or occlusion. In this classic example of hemodynamic ischemia, patients have recurrent, irregular, and involuntary movements of the contralateral arm, leg, or both, usually triggered by postural changes and lasting a few minutes.

Another important clue to ICA disease is the development of episodes of transient monocular blindness (TMB) (see Plate 9-12). TMB refers to the occurrence of temporary unilateral visual loss or obscuration that is described by careful observers as a horizontal or vertical “shade being drawn over one eye,” but most frequently as a “fog” or “blurring” in the eye lasting 1 to 5 minutes. It often occurs spontaneously but at times is triggered by position changes. Positive phenomena, such as sparkles, lights, or colors evolving over minutes, are typical of migrainous phenomenon and help to differentiate such benign visual changes from the more serious TMB, a frequent harbinger of cerebral infarct within the carotid artery territory. Rarely, with critical ipsilateral internal carotid stenosis, gradual dimming or loss of vision when exposed to bright light, such as glare from snow on a sunlit background, can be reported and is due to limited vascular flow in the face of increased retinal metabolic demand.

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