Cerebral Microembolism in Patients With Retinal Ischemia

Abstract

Background and Purpose-We investigated the frequency of cerebral microembolism detected by transcranial Doppler ultrasonography in patients with clinical evidence of retinal ischemia, including transient monocular blindness, central and branch retinal artery infarction, and ischemic oculopathy, and assessed its correlation with carotid artery stenosis. Methods-Records of 331 consecutive patients examined during a 47-month period at the Neurovascular Laboratory were reviewed. Of the original 453 intracranial arteries, 186 middle cerebral arteries (MCAs) satisfied qualifying criteria that excluded patients with cardiac embolic sources. Forty-five MCAs ipsilateral to the symptomatic eye constituted the study group. The control group consisted of 141 asymptomatic MCAs. Microembolus detection studies were performed on transcranial Doppler instruments equipped with special software, and the degree of carotid artery stenosis was measured by cerebral or MR angiography or by color duplex studies. Results-Microembolism was detected in 40.0% of study MCAs and 9.2% of controls (PϽ0.001). In the study group, microembolic signals were detected in 61.9% of MCAs tested within a week of symptom onset and 20.8% of those tested afterward (PϽ0.001). Severe (Ն70%) carotid stenosis or occlusion was more frequent in the study group (PϽ0.001). Microembolic signals were detected in 25.3% and 11.2%, respectively, of MCAs distal to carotid arteries with 70% to 100% and 0% to 69% stenosis (Pϭ0.013). Conclusions-In patients without cardiac embolic sources, cerebral microembolism is frequently present on the side of retinal ischemia, particularly during the week after onset of symptoms. It is often associated with severe stenosis or occlusion of the ipsilateral carotid artery.

Retinal vein and artery occlusions: a risk factor for stroke in atrial fibrillation

“…However, previous study populations differed in terms of site of lesion (arterial or venous) or type of ischemia (prolonged or transient monocular blindness, amaurosis fugax, a condition with several etiologies other than thromboembolism) [29], or contained no (or only few) patients with atrial fibrillation [14,17].…”

“…Carotid artery stenosis is known to be associated with retinal arterial occlusion, and is a well-established risk factor for stroke [14,[30][31][32]. In several studies, transient and prolonged retinal arterial ischemia was more likely to be associated with carotid stenosis than atrial fibrillation [30,33].…”

“…Patients with retinal vascular occlusions often present to general practitioners or ophthalmologists, and have previously been associated with various cardiovascular risk factors [7][8][9][10][11][12][13], cerebral microembolisms [14], and cardiovascular events, including stroke and myocardial infarction [11,[15][16][17]. However, another study found that risk factor prevalence differed somewhat between patients with retinal and cerebral ischemia, indicating that there might be pathogenetic differences between retinal and cerebral ischemia [18].…”

Cerebral Ischemia and Infarction From Atheroemboli <100 μm in Size

“…15 Patients with critical carotid stenosis have several factors, including age, hypertension, and/or diabetes, that could affect the microcirculation and increase the vulnerability of the brain to ischemic injury from microemboli. These patients also are likely to have had previous microembolic episodes that would reduce the available microcirculation collaterals [5][6][7][8][9] and further increase the potential risk.…”

“…[1][2][3][4] Spontaneous microemboli also occur in the carotid artery and can be detected during random TCD monitoring in 21% to 60% of patients with documented carotid stenosis. [5][6][7][8][9] The number of spontaneous microemboli shed may be greatest among symptomatic patients. Droste and colleagues 5 found up to 142 embolic signals per hour in patients with carotid stenosis and a recent transient ischemic attack.…”