Hemifacial spasm patient with ipsilateral total absence of common carotid artery, vertebral artery and aneurysm of the contralateral internal carotid artery

We present a case of a 45-year-old male patient with left hemifacial spasm for 6 years. Magnetic resonance tomographic angiography confirmed that there were small vessels adjacent to the left facial nerve root entry zone, but the left internal carotid artery (ICA) was absent. Magnetic resonance angiography using three-dimensional time of flight technique showed the absence of the left ICA and vertebral artery, But the presence of a 6-mm aneurysm in the bifurcation of the right internal carotid artery. These abnormal arterial structures were further confirmed by angiogram. Aortic arch angiogram revealed a right-sided aortic arch and the Subclavian steal phenomenon. The left common carotid artery and the left Subclavian artery were absent. Right vertebral angiography showed retrograde filling of the left vertebral artery. The left upper limb was fed by this artery. The aneurysm was successfully clipped. Post-operatively, the hemifacial spasm was weakened. However, the operation did not change the neurovascular positional relationship, thus we advised follow-up visits. Cerebral artery anomalies should be taken into consideration when performing imaging and surgical corrections in patients with hemifacial spasm.