A 59-year-old white female presented to the emergency room after slipping and falling on ice. She had a past medical history of hypertension, hyperlipidemia, and asthma. The patient smoked one half pack of cigarettes per day. An axial 3D time of flight magnetic resonance imaging (MRI) scan was performed and identified the absence of the left carotid canal with an absence of flow signal (Figure ). An unusual vessel was also seen to arise from the right cavernous internal carotid artery (Figure ). The vessel traveled in the floor of the sella turcica (Figure ). Additional imaging with 3D reconstruction from a computed tomography (CT) angiography better defined an aberrant origin of the left internal carotid artery (Figure ). CT angiography noted the presence of an anterior communicating artery aneurysm, which was bilobed and measured 7 x 11 mm. The physical examination was unremarkable for any neurological deficits. Angiography found that the aneurysm was not amenable to endovascular treatment. Therefore, the patient underwent a right-sided craniotomy for clipping of her complex aneurysm and was soon discharged home with no complications.
A 25-year-old female patient visited the neurology outpatient clinic with severe holocranial headache that had persisted for 2 months. The pain was intermittent and relieved by analgesics. Clinical examination was unremarkable.\nComputed tomography (CT) scan of the brain showed absent bony carotid canal on the left side [Figure and ]. Magnetic resonance angiography (MRA) [Figure and ] showed complete absence of the cervical and petrous part of the left ICA. An abnormal vessel was seen arising from the cavernous segment of the right ICA. This vessel was passing across the floor of sella, reconstituting the cavernous and supraclinoid segments of the left ICA, and continuing as the left MCA. Aplasia of A1 segment of left ACA was also observed.\nMagnetic resonance imaging (MRI) showed absent left ICA flow void with an abnormal flow void in the sella [Figure and ]. No evidence of any SAH or aneurysm was seen. The vertebrobasilar system was normal.\nDoppler imaging [Figure –] showed complete absence of the left ICA. The left common carotid artery (CCA) was seen continuous with the external carotid artery (ECA). The left CCA and ECA showed high resistance flow with narrow systolic peak and low diastole. Since the right CCA has to compensate for the absent left ICA, it showed low resistance flow with broad systolic peak and high diastolic flow.\nLateral radiograph of the skull [] and the corresponding sagittal reformatted CT scan [] showed a well-defined lytic area in the anteroinferior aspect of the sella due to the abnormal intercavernous vessel traversing across it.