Extra-Carotid Arterial Webs: A Single-Center Series and Systematic Review

BACKGROUND: Carotid webs are increasingly recognized as a cause of ischemic stroke, but less is known about morphologically similar lesions in other arteries. We present the first study characterizing the clinical and radiographic features of extra-carotid arterial webs through a single-center case series and systematic review. METHODS: Patients with possible extra-carotid webs were identified from 2017 to 2025 using a natural language processing search of radiology reports at our institution. Candidate cases underwent imaging review with multiplanar and 3-dimensional reconstructions to distinguish webs from fenestrations, vessel tortuosity, dissection, or atherosclerotic plaque. In parallel, we performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses–compliant systematic review (Web of Science and PubMed, inception to September 2025) to identify published cases of extra-carotid web. Data on demographics, vascular location, imaging modality, clinical presentation, treatment, and outcomes were extracted and synthesized descriptively. RESULTS: Four extra-carotid webs were identified at our institution (3 basilar and 1 subclavian). None were associated with stroke, and all patients remained stable on conservative management during 9 months to 4 years of follow-up. Across 16 published studies, 22 additional extra-carotid webs were identified, yielding 26 patients in aggregate (mean age, 52.7 years; 61.5% male). The vertebral artery was the most common site (53.8%), followed by the basilar (30.8%) and subclavian (15.4%) arteries. Ten patients with vertebral or basilar web presented with posterior circulation ischemic stroke, with recurrent events in 4 patients. Most patients were managed with antiplatelet therapy or observation, while 3 vertebral webs with recurrent stroke were successfully treated with stenting. CONCLUSIONS: Extra-carotid webs share morphological and clinical features with carotid webs and may represent a unified disease spectrum of cervical artery webs. Vertebral and basilar webs, though rare, may be an underrecognized source of posterior circulation stroke. Recognition of these lesions may broaden the differential for cryptogenic stroke though the lack of histopathologic visualization remains a critical limitation of our study.