Microembolic Signals Detected by Transcranial Doppler Sonography During Carotid Endarterectomy and Correlation With Serial Diffusion-Weighted Imaging

Abstract

Background and Purpose-Embolic events are a major cause for procedure-related strokes after carotid endarterectomy (CEA). Transcranial Doppler sonography can reveal embolic events as microembolic signals (MES) during CEA. MES during declamping and shunting are frequently detected. MES during shunting are rare and known to be correlated with the neurological outcome of the patient. In the present study, we analyzed the occurrence of MES within different stages of CEA and whether MES within those stages were correlated with cerebral ischemia, as detected by diffusion-weighted imaging (DWI), and brain infarction, as detected by contrast-enhanced MRI. Methods-Thirty-three patients were monitored intraoperatively for MES using transcranial Doppler sonography. DWI was performed within 24 hours before and after surgery. Positive postoperative DWI led to reexamination with contrast-enhanced T1-MRI 7 to 10 days after CEA for detection of cerebral infarction. Results-MES were detected in 32 of 33 patients. The highest number of MES was found during shunting and declamping.A significant correlation was found between MES and DWI-lesions during dissection. A significant correlation was found between MES during dissection and shunting, and nonsignificant correlation was found between MES and the occurrence of cerebral infarction. Conclusion-MES

Incidence of Ischemic Lesions by Diffusion-Weighted Imaging After Carotid Endarterectomy With Routine Shunt Usage

“…Transcranial Doppler sonography has shown that the highest number of microembolic signals is detected during the declamping period. 17) We consider that shunting itself does not increase the risk of ischemic lesion, even clinically silent lesions detected only by diffusion-weighted MR imaging, if the shunt device is carefully used with meticulous preparation before insertion, and careful rinsing with heparinized saline through the third lumen as detailed in our endarterectomy method.…”

“…3,10,12) Therefore, the most common strategy to prevent ischemia during CEA is selective shunt usage based on the findings of electroencephalography (EEG), stump pressure, or transcranial Doppler sonography, to reduce the risk of embolic complication resulting from shunt device insertion or removal, 2,11,16) as shunting carries the risk of embolus release. 6,12,17) However, the intraoperative decisionmaking for selective shunt usage following monitoring changes during cross-clamping requires vast experience. In fact, most CEA series with good results performed with EEG monitoring and selective shunting occurred at large centers.…”

Transcranial Doppler Ultrasound Detection of Microemboli as a Predictor of Cerebral Events in Patients with Symptomatic and Asymptomatic Carotid Disease: A Systematic Review and Meta-Analysis

“…Nineteen studies, with a total of 5570 individual patients, reported stroke as an outcome along with data for TCD recording of microembolic signals (7)(8)(9)(10)13,16,(18)(19)(20)23,(27)(28)(29)(30)(31)(32)(33)(34). The sensitivity and specificity were 73.14 (95% CI 48.16 to 88.86) and 70.27 (95% CI 58.61 to 79.78)* respectively.…”

“…Eight studies, with a total of 1414 individual patients, reported stroke or TIA as an outcome along with data for TCD recording of microembolic signals with high MES counts defined as positive (13,(17)(18)(19)21,32,33,35). The sensitivity and specificity were 52.…”

The impact of carotid revascularization on cognitive function

“…1,[20][21][22] Along the same lines, other studies have demonstrated that manipulation of the carotid artery during revascularization can cause atheroembolization with consequent silent cerebral microinfarcts. 1,[23][24][25] Transcranial Doppler (TCD) can differentiate gaseous from particulate microembolic material during revascularization procedures. 26,27 Gaunt et al…”