THE SIGNIFICANCE OF MICROEMBOLI DETECTION BY MEANS OF TRANSCRANIAL DOPPLER ULTRASONOGRAPHY MONITORING IN CAROTID ENDARTERECTOMY

Purpose: Carotid endarterectomy (CEA) performed with continuous transc ranial Doppler monitoring provides a unique opportunity to determine t he number of cerebral microemboli and to relate their occurrence to th e surgical technique. The purpose of this study was to assess in CEA t he impact of cerebral microembolism on clinical outcome and brain arch itecture. We also evaluated the influence of the audible transcranial Doppler signal on the surgeon and his or her technique. Methods: In a prospective series of 301 patients, CEA was monitored with electroence phalography and transcranial Doppler ultrasonography of the ipsilatera l middle cerebral artery. Preoperative and intraoperative risk factors were entered in a logistic regression analysis program to assess thei r correlation with cerebral outcome. To evaluate the impact of cerebra l microembolism on brain architecture, we compared preoperative and po stoperative computed tomography scans or magnetic resonance images of the brain in two subgroups of 58 and 40 patients, respectively. Result s: Seven (2.3%) patients had intraoperative transient ischemic symptom s, three (1%) had intraoperative strokes, 1 (0.3%) had transient ische mic symptoms after operation, and 10 (3.3%) had postoperative strokes. Pour (1.3%) patients died. Microemboli (>10) noticed during dissectio n were related to both intraoperative (P < 0.002) and postoperative (p < 0.02) cerebral complications. Microemboli that occurred during shun ting were also related to intraoperative complications (P < 0.007). Mi croembolism never resulted in new morphologic changes on postoperative computed tomography scans. On the contrary, the phenomenon of more th an 10 microemboli during dissection was significantly (P < 0.005) rela ted to new hyperintense lesions on postoperative T2-weighted magnetic resonance images. Conclusions: During CEA the presence of microembolis m (>10 microemboli) during dissection shows a statistically significan t 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 compli cations. Surgeons can be guided by the audio Doppler and emboli signal s by changing their technique. This change may result in a decrease of microembolism and consequently in a decline of the intraoperative str oke rate.