Transcranial Doppler in 178 Patients Before, During, and After Carotid Endarterectomy

Abstract

From July 1991 to March 1995, 178 patients who underwent 198 carotid surgical repairs were investigated preoperatively, intraoperatively, and postoperatively by transcranial Doppler sonography (TCD). Preoperative TCD evaluation showed stenosis of the middle cerebral artery (MCA) in 4 patients (2.2%), siphon stenosis in 3 (1.6%), incomplete circle of Willis in 23 (12.9%), a decrease of mean blood flow velocity more than 70% of the basal value during digital common carotid compression in 31 (17.9%), and a critical reduction of vasomotor reactivity (no significant increase of mean blood flow velocity in the MCA during breath-holding test) in 34 (19.1%). Nine patients (5%) had surgery without preoperative angiography. In those patients the indication for surgery was based on color Doppler imaging and TCD investigations. Ninety surgical procedures were carried out under general anesthesia and 188 under locoregional anesthesia. In 37 surgeries (31.7%) a shunt was inserted. The use of a shunt was based on a decrease of mean blood flow velocity in the MCA below 50% of the basal value under general anesthesia or loss of consciousness combined with a decrease of mean blood flow velocity in the MCA higher than 70% of the basal value when locoregional anesthesia was employed. Intraoperative TCD monitoring showed a decrease of mean blood flow velocity in the MCA due to shunt malfunction in (8.3%) of 36 surgeries, turbulence of blood flow during declamping in 79 procedures (39.8%), and microembolic events in 10 patients (5%) that were related to one transient and one permanent neurological deficit. Another permanent deficit occurred in a patient without TCD signs. After surgery, TCD reliably detected an early asymptomatic occlusion of the carotid artery, hyperperfusion syndrome in 12 (6.0%), and an increase of vasomotor reactivity in 10 (29.4%) of 34 surgeries.

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

“…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. 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.…”

Diagnostic Criteria and Yield of Real-Time Transcranial Doppler Monitoring of Intra-Arterial Reperfusion Procedures

“…Головные устройства для проведения ТКДГ-мониторинга пропускают рентгеновское излучение, только передатчики и ручки-замки оставляют неболь-шой узнаваемый след на изображениях субтракци-онной ангиографии. Эти рентгеноконтрастные части можно удалить с изображения или вывести из плос-кости стандартных проекций, что делает возможным применение ТКДГ-мониторинга при проведении ВА реперфузионных процедур [16]. Цель нашего иссле-дования заключалась в описании диагностических критериев и изучении эффективности неинвазивно-го ТКДГ-мониторинга по получаемой ультразвуковой картине, верифицированной одновременным диагнос-тическим введением контрастного препарата во время ВА реперфузионных процедур.…”

“…These radio-opaque parts can be removed or placed out of plane for standard projections, making application of TCD monitoring feasible during IA reperfusion procedures. 16 Our aim was to describe diagnostic criteria and yield of noninvasive TCD monitoring derived from ultrasound tracings verified by simultaneous diagnostic dye injections during IA reperfusion procedures.…”

Hyperperfusion Syndrome After Intracranial Angioplasty and Stent Placement

“…3 However, Rezende fails to indicate that other reports examining the incidence of cerebral hyperperfusion syndrome using perioperative transcranial Doppler studies have reported rates of up to 9%. 4,5 Because the clinical findings in cerebral hyperperfusion syndrome may be subtle and ancillary investigations examining postprocedural cerebral blood flow, such as brain perfusion CT, nuclear medicine single-photon emission CT, xenon CT, and transcranial Doppler sonography, are not often performed, one may expect a significant reporting bias that can skew the published data.…”