The significance of microemboli detection by means of transcranial Doppler ultrasonography monitoring in carotid endarterectomy

Abstract

During CEA the presence of microembolism (> 10 microemboli) during dissection shows a statistically significant relationship with perioperative cerebral complications and with new ischemic lesions on magnetic resonance images of the brain. Moreover, microembolism during shunting is also related to intraoperative complications. Surgeons can be guided by the audio Doppler and emboli signals by changing their technique. This change may result in a decrease of microembolism and consequently in a decline of the intraoperative stroke rate.

Silent Cerebral Ischemia Detected by Diffusion-Weighted MRI After Carotid Endarterectomy

“…34 Several studies have found that the occurrence of postoperative cerebral ischemia is correlated with increased numbers of sonographic microemboli. 8,10,11 Given the small sample size of the present study and the relatively low rate of observed microemboli, our results do not allow any conclusion concerning the number of sonographic embolic signals and the occurrence of radiologically detectable cerebral lesions.…”

“…The rate of postoperative silent infarction was higher than in CT-based reports and ranged from 0% to 24%. 8,12,13,33 Still higher rates of silent ischemia would probably have been demonstrated in these MRI studies if they had been supplemented by diffusion-weighted sequences. In the present series, the probability of missing postoperative ischemic lesions was particularly small because DWI was performed in the first 24 hours after the operation to detect any short-lived cerebral changes.…”

“…Very high percentages (up to 95%) have been reported by several groups of investigators. 5,[7][8][9][10][11][12][13] Exclusion of the sonographic signals that occur at and immediately after declamping greatly reduces the overall rate of detected microemboli. In one study considering only emboli occurring at flow restoration, a rate as low as 5% was reported along with what were considered to be flow turbulence signals in 40% of cases.…”

“…5,[7][8][9][10][11][12][13] It has been suggested that increased cerebral microembolization may positively correlate with postoperative deterioration of cognitive function or the appearance of lacunar infarcts on MRI. 7,8 However, the clinical relevance of sonographic embolic signals remains unclear because most of them are not associated with focal neurological deficits. 14,15 Whether embolic signals represent an increased risk of postoperative silent brain ischemia also remains to be determined.…”

Microemboli Monitoring in Ischemic Stroke

“…Presence of microemboli during carotid endarterectomy is an indicator of new ischemic events (Ackerstaff, Moons et al 2000) (Ackerstaff, Jansen et al 1995). Presence of microemboli should alert the physician to change the surgical technique.…”