To present a case on bilateral internal carotid artery (ICA) agenesis found incidentally in the setting of trauma.

Congenital absence of the ICA is exceedingly rare, with incidence estimated at fewer than 0.01%. Bilateral involvement is markedly rarer, with only 33 cases of bilateral agenesis reported in the literature. Sometimes found incidentally, many presented for some neurologic complaint that prompted imaging.

A 22-year-old male presented as a level 2 trauma following a pedestrian vs motor vehicle collision. Neurologic exam was unremarkable, GCS 14. Patient was found to have multiple rib fractures, a pneumothorax, a pelvic ring fracture, and eviscerated right testicle on initial evaluation. A CTA neck performed revealed bilateral absence of ICAs. Given the extensive nature of his injuries and mechanism thereof, initially this was interpreted as dissection, which promptly involved neurology for consideration of intervention. Upon closer imaging review, patient lacked carotid canals bilaterally, and had hypertrophied posterior communicating arteries, thus the patient was deemed to have bilateral ICA agenesis.

Depending on the patient's presentation, coupled with rare occurrence, diagnosis can be challenging. Other causes, such as atherosclerotic steno-occlusive disease and dissections, remain high on the differential. In our case, the patient’s trauma with multiple fractures led to an immediate dilemma, with prompt neurology involvement. Our patient’s incidental finding initially mistaken for dissection, is a unique presentation for this already rare condition. Recognizing this anomaly is crucial to avoid unnecessary workups and potential morbidity. At a smaller institution, this patient may have been immediately transferred elsewhere for neurointerventional evaluation, and in some cases, may have proceeded emergently to invasive cerebral angiogram, posing unnecessary risks. Our case adds to the limited literature on this vascular anomaly, stressing the importance of its recognition to mitigate avoidable workup and intervention, while highlighting a unique presentation.