Atypical Carotid Webs: An Elusive Etiology of Ischemic Stroke.

Objective: Typical carotid webs are nonatherosclerotic shelf-like projections of fibromyxoid tissue extending from the posterior wall of the proximal internal carotid artery. Carotid webs may precipitate acute embolic stroke, especially in younger patients. We describe our experience with pathology-proven carotid webs of atypical appearance, or atypical carotid webs (ACWs), a subset of carotid webs exhibiting abnormal location, morphology, or association with atherosclerotic changes.

Methods: Our electronic medical record database was queried for all imaging impressions containing "carotid web," "shelf," or "protrusion" from 2018 to 2024. Imaging was reviewed by an experienced neuroradiologist and neurosurgeon. Patients with typical carotid webs or those with different diagnoses (e.g. dissection/thrombus) were excluded.

Results: Twenty-seven patients were treated for typical carotid webs; 24 were treated with carotid endarterectomy (CEA) and had pathology-confirmed webs. Five patients (3 male) were identified to have ACWs and included in this report. The mean age was 43.6 years. All ACWs were identified by computed tomography angiography. All patients presented with acute ischemic stroke or transient ischemic attack. One web was located on the anterior internal carotid artery wall, 3 were of abnormal morphology different from a "shelf-like" projection, and one was associated with atherosclerotic change. No patients experienced a further stroke or transient ischemic attack following CEA.

Conclusions: ACWs may precipitate ischemic stroke and can be treated and definitively diagnosed with CEA. Due to their unusual appearance, ACWs may evade radiographic identification or be misdiagnosed. As ACWs have not been previously reported in the literature, awareness of their existence must be raised to increase their detection and treatment.