A 46-year-old woman with no previous medical history first visited ophthalmologic department with amaurosis fugax for about 20 min and persistent visual impairment of left eye. The corrective vision examination showed that visual accuracy of the left eye is 0.1 and the right eye is normal 1.0. Pupillary light reflex test showed relative afferent pupillary defect (RAPD) of the left eye. The fundus examination did not find significant abnormalities (Fig. A). The Visual-Evoked Potential (VEP) test demonstrated the prolonged latency and declined amplitude of P100 wave of the left eye (Fig. B), indicating the impairment of left visual pathway. The fundus fluorescein angiography found that the arm-retinal circulation time of left eye was 25 s (Fig. C and Additional file : Video 1), whereas the normal time window is only 10 ~ 15 s. The right eye did not present any abnormality (Fig. C). Accordingly, the CRAO diagnosis was confirmed and ophthalmologic examination indicated that the occlusion might occur in the pathway from aortic arch to ophthalmic artery.\nTherefore, the patient was transferred to neurological department. The MR angiography (MRA) found that bilateral ICAs were absent concurrent with dilated vertebral and basilar arteries. Meanwhile, there were variations in the circle of Willis with opened right posterior communication artery (PCoA) and absence of left PCoA (Fig. A). Moreover, CT angiography (CTA) images (Fig. B, C) illustrated that bilateral hypoplasia of the ICAs from carotid bifurcation with thin remnants and the bilateral bony carotid canals still existed in CT bone window (Fig. D), confirming the diagnosis of bilateral ICAs hypoplasia but not ICAs agenesis. Hereto, we can depict the characteristics of the blood flow of the case: (1) due to bilateral ICAs hypoplasia, vertebrobasilar artery system takes the responsibility to provide blood supply to the whole brain and results in dilated vertebral and basilar arteries; (2) as a result of variation of the circle of Willis, the blood flow first supplies right middle cerebral artery (MCA) and ophthalmic artery via opened right PCoA and then the left MCA and ophthalmic artery via opened anterior communicating artery (ACoA).\nHowever, the amaurosis fugax and lasting visual impairment of left eye cannot be well interpreted. According to the standard of TOAST typing of stroke, the cardiogenic factors were evaluated then. Atrial fibrillation and valve vegetation were not detected by 24-h dynamic electrocardiogram and echocardiograms. Transesophageal echocardiography (TEE) revealed patent foramen ovale (Fig. ) and blood split-flow from right to left atrium when doing Valsalva breath during the Foaming test (Additional file : Video 2). Therefore, the amaurosis fugax and persistent visual impairment of left eye was caused by cardiogenic embolism.\nAspirin 100 mg/day was given to the patient and PFO occlusion surgery was recommended by us. However, the patient refused the surgery and was lost to follow-up.
The patient was a 63-year-old female with hypertension and diabetes. She had no history of smoking or heart disease. She had undergone surgery to clip a cerebral aneurysm 3 years previously and the treating neurosurgeon responsible at the time had reported difficulty with catheterization of cervical arteries. She was examined with Doppler ultrasonography of carotid and vertebral arteries, which showed that the left common carotid artery had a smaller caliber than the right ( ), the left carotid bifurcation could not be observed, and the left common carotid artery only led to the left external carotid artery ( ). Angiotomography was ordered, showing agenesis of the left internal carotid artery ( ). The patient remains asymptomatic and attends regular follow-up consultations.