Posterior Cerebral Circulation Insufficiency Due to Internal Carotid Artery Stenosis With an Atypical Vertebral Artery Originating From the Internal Carotid Artery Territory

Aberrant anatomical variation of the vertebral artery (VA) from an internal carotid artery (ICA) is considered a rare finding. The incidence of this phenomenon can lead to patients suffering from posterior circulation neurological deficit if the ICA becomes significantly diseased. VA atypical anatomical origin is considered one of the rare pathologies, not only precipitating neurovascular incidents but equally leading to severe difficulty in VA dissection and surgical exposure, especially in carotid artery procedures. The "vertebral arteria lusoria," despite its rare incidence, ought to be considered in cases undergoing upper gastrointestinal surgeries; thus, not knowing this pathology may lead to life-threatening incidents. Furthermore, double origins of VA could be noticed in the pre-operative assessment of cases with extracranial pathology. Strokes in the posterior cerebral vascular territory, which are vertebral-basilar arteries and spinal cord perfusion deficiency, are frequently mentioned impediments to VA injury in patients with normal or aberrant VA origins. Consequently, dominant atypical VA, in absentia, atresia of the artery, completely thrombosed contralateral VA, and failure to assess the vertebrobasilar perfusion are solid triggering signs to preserve subclavian artery and atypical VA perfusion. We report a rare case of a 76-year-old female who presented with intermittent dizziness, left facial numbness, and left arm paresthesia. On investigation with computed tomographic angiography (CTA), she was incidentally found to have an aberrant anatomy of a dominant right VA arising from her right ICA and severe stenosis in the right ICA origin of 70% significant stenosis. Patients with posterior circulation symptoms and ICA stenosis may have aberrant anatomy. High-quality imaging in the form of CTA is essential prior to deciding whether and what surgery is indicated.