Abstract Number ‐ 220: Internal Carotid Artery Hypoplasia of Unique Anatomical Variance

Introduction Hypoplasia of the internal carotid artery (ICA) is incomplete development of the ICA with the presence of empty carotid canal. Despite anecdotal data reporting less than a 0.01% of developmental anomalies of ICA, the true incidence remains unknown. Many cases are asymptomatic and thus escape diagnostic detection or appropriate intervention. In 1968, Lie and Hage described collateral circulation in ICA developmental anomalies through the Circle of Willis, persistent embryonic vessels, or skull base arteries/anastomosis or rete mirabile. While collateral systems exist, subsequent cerebrovascular insufficiency and vascular malformations may occur as a result. To our knowledge, there is an incomplete body of literature surrounding the implications of ICA hypoplasia of varying anatomy. Methods We present a case report of left ICA hypoplasia and a comprehensive literature review. Results A 70‐year‐old woman with hypertension, nicotine dependence, and chronic obstructive pulmonary disease (COPD) presented with COPD exacerbation and disorientation. Computed tomography (CT) head angiography showing left cervical/petrous ICA aplasia with presence of a small carotid canal. The left external carotid and vertebral artery originate at the aortic arch. Majority of the blood supply to the left anterior cerebral artery (ACA) and middle cerebral artery (MCA) is suppliedby the right anterior communicating artery (AComA), posterior communicating artery (PComA). There is also a small left supraclinoid and carotid terminus that reconstitute predominantly by right A1 segment and PComA (Figure 1). Conclusions Although ICA hypoplasia may be an incidental finding, accurate and promptrecognition is essential for the consideration of endovascular implications, screening for vascular malformations, understanding cerebral vascular flow, managing cerebrovascular risk, and avoiding misinterpretation of clinical and imaging patterns.