Chronic Occlusion of the Internal Carotid Artery with a Hypertrophied Vas Vasorum, Mimicking High-Grade Stenosis

A 75-year-old woman presented with a pulsatile bruit on the left side of her head. She had a family history of ischemic strokes. The neurological examination did not reveal any neurological deficit. Magnetic resonance imaging revealed an occlusion of the right internal carotid artery (ICA). No cerebral infarction was found. Contrast-enhanced magnetic resonance angiography of the neck demonstrated an atherosclerotic near-occlusion involving the proximal right ICA. CT perfusion after intravenous (IV) administration of 1 g acetazolamide revealed asymmetric perfusion with a deficit in the affected area of the right anterior circulation. Despite the patient’s advanced age, a decision was made to reconstruct the lumen of the right ICA with stent angioplasty. Preprocedural digital subtraction angiography did not indicate a near-occlusion. Instead, it showed an enlarged vas vasorum, which originated from the proximal ICA lumen and penetrated through the occluded vessel wall. The magnetic resonance angiography finding that appeared to be a high-grade ICA stenosis was, in fact, an occlusion, which was collateralized by a vas vasorum. Passage of the guidewire (and balloon catheter) necessary for stent angioplasty of the target vessel was impossible. Therefore, the endovascular procedure was terminated. The patient declined the proposed surgical endarterectomy or extra-intracranial bypass surgery. For secondary prophylaxis, 100 mg acetylsalicylic acid per os daily was prescribed. This chapter discusses enlarged vasa vasorum in proximal ICA occlusion, which can mimic near-occlusion. Most cases of enlarged vasa vasorum do not permit a guidewire and balloon catheter passage. Although near-occlusive stenoses of the ICA are frequently amenable to stent angioplasty, enlarged vasa vasorum cannot be catheterized. If the continuity or at least the blood supply of the ICA should be reestablished, surgical endarterectomy or bypass surgery is required. The phenomenon of hypertrophic vasa vasorum is the main topic of this chapter.