CEREBRAL MICROEMBOLISM IN PATIENTS WITH RETINAL ISCHEMIA

Background and Purpose-We investigated the frequency of cerebral micro embolism detected by transcranial Doppler ultrasonography in patients with clinical evidence of retinal ischemia, including transient monocu lar blindness, central and branch retinal artery infarction, and ische mic oculopathy, and assessed its correlation with carotid artery steno sis. Methods-Records of 331 consecutive patients examined during a 47- month period at the Neurovascular Laboratory were reviewed. Of the ori ginal 453 intracranial arteries, 186 middle cerebral arteries (MCAs) s atisfied qualifying criteria that excluded patients with cardiac embol ic sources. Forty-five MCAs ipsilateral. to the symptomatic eye consti tuted the study group. The control group consisted of 141 asymptomatic MCAs, Microembolus detection studies were performed on transcranial D oppler instruments equipped with special software, and the degree of c arotid artery stenosis was measured by cerebral or MR angiography or b y color duplex studies. Results-Microembolism was detected in 40.0% of study MCAs and 9.2% of controls (P<0.001). In the study group, microe mbolic signals were detected in 61.9% of MCAs tested within a week of symptom onset and 20.8% of those tested afterward (P<0.001). Severe (g reater than or equal to 70%) carotid stenosis or occlusion was more fr equent in the study group (P<0.001). Microembolic signals were detecte d in 25.3% and 11.2%, respectively, of MCAs distal to carotid arteries with 70% to 100% and 0% to 69% stenosis (P=0.013), Conclusions-In pat ients without cardiac embolic sources, cerebral microembolism is frequ ently present on the side of retinal ischemia, particularly during the week after onset of symptoms. It is often associated with severe sten osis or occlusion of the ipsilateral carotid artery.