Transcranial Doppler in 178 patients before, during, and after carotid endarterectomy

Comparative Analysis of Somatosensory-Evoked Potentials and Transcranial Doppler Ultrasound for Cerebral Ischemia Detection in Carotid Endarterectomy: Insights from Network Meta-Analysis and Clinical Data

OBJECTIVE

This study aims to compare the diagnostic efficacy of somatosensory-evoked potentials (SEPs) and transcranial Doppler sonography (TCD) for monitoring cerebral tissue ischemia during carotid endarterectomy (CEA) using network meta-analysis and retrospective analysis of clinical data.

METHODS

For the meta-analysis, we conducted a comprehensive search of 4 electronic databases (PubMed, EMBASE, Cochrane, and Web of Science) from inception to September 2023, resulting in the inclusion of 52 relevant articles. Additionally, a retrospective study was conducted at our hospital, involving patients who underwent CEA surgery from July 2019 to July 2021.

RESULTS

The network meta-analysis incorporated 52 articles, with ranking results indicating that SEP demonstrated superior performance in specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy with surface under the cumulative ranking curve values of 99.9%, 93.8%, 96.6%, and 99.9%, respectively. Furthermore, TCD exhibited the highest sensitivity with a surface under the cumulative ranking value of 92.0%. A total of 190 patients meeting inclusion criteria were included in the retrospective study. The area under the curve for SEP's receiver operating characteristic curve was 0.787, compared to TCD's area under the curve of 0.606. SEP demonstrated a sensitivity of 66.67%, with a specificity of 90.76%, PPV of 19.05%, NPV of 98.82%, and accuracy of 90%. For TCD, the diagnostic performance measures included a sensitivity of 50.00%, specificity of 71.19%, PPV of 5.35%, NPV of 97.76%, and accuracy of 70.53%. The Fisher's exact test for sensitivity yielded a result of P = 1.000. The χˆ2 test for specificity resulted in χˆ2 = 22.863, with P < 0.001. Continuous correction χˆ2 tests for PPV and NPV showed χˆ2 = 2.005 (P = 0.157) and χˆ2 = 0.069 (P = 0.793), respectively. Additionally, the χˆ2 test for accuracy showed χˆ2 = 22.742, with P < 0.001.

CONCLUSIONS

During CEA, SEP appears to provide a slightly more reliable indication of the ischemic condition in cerebral tissues compared to TCD.

A systematic review & meta-analysis on perioperative cerebral and hemodynamic monitoring methods during carotid endarterectomy

OBJECTIVE

To compare outcomes between different strategies of perioperative cerebral and hemodynamic monitoring during carotid endarterectomy.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL databases were searched.

METHODS

This review was performed according to the PRISMA guidelines and prospectively registered in the international prospective register of systematic reviews (CRD42021241891). The GRADE approach was used to describe the methodological quality of the studies and certainty of the evidence. The primary outcome was 30-day stroke rate. Secondary outcomes measures are 30-day ipsilateral stroke, 30-day mortality, shunt rate and complication rates.

RESULTS

The search identified 3 460 articles. Seventeen RCTs, three prospective observational studies and seven registries were included, reporting on 236 983 patients. The overall pooled 30-day stroke rate is 1.8% (95% CI 1.4 - 2.2%), ranging from 0 - 12.6%. In RCT's the pooled 30-day stroke rate is 2.7% (95% CI 1.6 - 3.7%) compared to 1.3% (95%CI 0.8 - 1.8%) in the registries. The overall stroke risk decreased from 3.7% before the year 2000 to 1.6% after 2000. No significant differences could be identified between different monitoring and shunting strategies, although a trend to higher stroke rates in routine no shunting arms of RCTs was observed. Overall 30-day mortality, myocardial infarction and nerve injury rates are 0.6% (95%CI 0.4 - 0.8), 0.8% (95%CI 0.6-1.0) and 1.3% (95%CI 0.4-2.2), respectively.

CONCLUSIONS

No significant differences between the compared shunting and monitoring strategies are found. However, routine no shunting is not recommended. The available data is too limited to prefer one method of neuromonitoring over another method when selective shunting is applied.

Intracerebral hemorrhage as a manifestation of cerebral hyperperfusion syndrome after carotid revascularization: systematic review and meta-analysis

BACKGROUND

Intracerebral hemorrhage (ICH) in the context of cerebral hyperperfusion syndrome (CHS) is an uncommon but potentially lethal complication after carotid revascularization for carotid occlusive disease. Information about its incidence, risk factors and fatality is scarce. Therefore, we aimed to perform a systematic review and meta-analysis focusing on the incidence, risk factors and outcomes of ICH in the context of CHS after carotid revascularization.

METHODS

We searched the PubMed and EBSCO hosts for all studies published in English about CHS in the context of carotid revascularization. Two reviewers independently assessed each study for eligibility based on predefined criteria. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the PROSPERO register was made (register no. CRD42016033190), including the pre-specified protocol.

RESULTS

Forty-one studies involving 28,956 participants were deemed eligible and included in our analysis. The overall quality of the included studies was fair. The pooled frequency of ICH in the context of CHS was 38% (95% CI: 26% to 51%, I2 = 84%, 24 studies), and the pooled case fatality of ICH after CHS was 51% (95% CI: 32% to 71%, I2 = 77%, 17 studies). When comparing carotid angioplasty with stenting (CAS) with carotid endarterectomy (CEA), post-procedural ICH in the context of CHS was less frequent in CEA. ICH following CHS occurred less often in large series and was rare in asymptomatic patients. The most common risk factors were periprocedural hypertension and ipsilateral severe stenosis.

CONCLUSIONS

ICH as a manifestation of CHS is rare, more frequent after CAS and associated with poor prognosis. Periprocedural control of hypertension can reduce its occurrence.

Transcranial Doppler Monitoring in Carotid Endarterectomy: A Systematic Review and Meta-analysis

OBJECTIVES

To evaluate the efficacy of intraoperative transcranial Doppler monitoring in predicting perioperative strokes after carotid endarterectomy (CEA).

METHODS

An electronic search of PubMed, Embase, and Web of Science databases was conducted for studies on transcranial Doppler monitoring in CEA published from January 1970 through September 2015. All titles and abstracts were independently screened on the basis of predetermined inclusion criteria, which included randomized clinical trials and prospective or retrospective cohort reviews, patients who underwent CEA with intraoperative transcranial Doppler monitoring (either middle cerebral artery velocity [MCAV] or cerebral microembolic signals [MES]) and postoperative neurologic assessments up to 30 days after the surgery, and studies including an abstract, published in English on adult humans 18 years and older with a sample size of 50 or greater.

RESULTS

A total of 25articles with a sample population of 4705 patients were analyzed. Among the study patients, 189 developed perioperative strokes. Transcranial Doppler monitoring (either MCAV or MES) showed specificity of 72.7% (95% confidence interval [CI], 61.2%-81.8%) and sensitivity of 56.1% (95% CI, 46.8%-65.0%) for predicting perioperative strokes. Intraoperative MCAV changes during CEA showed strong specificity of 84.1% (95% CI, 74.4%-90.6) and sensitivity of 49.7% (95% CI, 40.6%-58.8) for predicting perioperative strokes.

CONCLUSIONS

Patients with perioperative strokes are 4 times more likely to have had transcranial Doppler changes (either MCAV or MES) during CEA compared to patients without strokes. Simultaneous MCAV and MES monitoring by transcranial Doppler sonography and combined intraoperative monitoring of transcranial Doppler sonography with somatosensory evoked potentials and electroencephalography during CEA to predict perioperative stroke could not be evaluated because of a lack of clinical studies combining these measures.

What Should We Do with Asymptomatic Carotid Stenosis?

The benefit of prophylactic carotid endarterectomy (CEA) for patients with asymptomatic severe carotid stenosis in the major randomised surgical studies was small, expensive and may now be absorbed by improvements in best practice medical intervention. Strategies to identify patients with high stroke risk are needed. If surgical intervention is to be considered the complication rates of individual surgeons should be available. Clinicians will differ in their interpretation of the same published data. Maintaining professional relationships with clinicians from different disciplines often involves compromise. As such, the management of a patient will, in part, depend on what kind of specialist the patient is referred to. The clinician's discussion with patients about this complex issue must be flexible to accommodate differing patient expectations. Ideally, patients prepared to undergo surgical procedures should be monitored in a trial setting or as part of an audited review process to increase our understanding of current practice outcomes.

Reporting standards for angioplasty and stent-assisted angioplasty for intracranial atherosclerosis

BACKGROUND AND PURPOSE

Intracranial cerebral atherosclerosis causes ischemic stroke in a significant number of patients. Technological advances over the past 10 years have enabled endovascular treatment of intracranial atherosclerotic stenosis. The number of patients treated with angioplasty or stent-assisted angioplasty for this condition is increasing. Given the lack of universally accepted definitions, the goal of this document is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting clinical and radiological evaluation, technique, and outcome of endovascular treatment using angioplasty or stent-assisted angioplasty for stenotic and occlusive intracranial atherosclerosis.

SUMMARY OF REPORT

This article was written under the auspices of Joint Writing Group of the Technology Assessment Committee, Society of NeuroInterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebrovascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and the Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1997 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data in stenotic intracranial atherosclerosis that could be used as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This document offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of intracranial stenotic and occlusive atherosclerosis. Included in this guidance document are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications.

CONCLUSION

In summary, the definitions proposed represent recommendations for constructing useful research data sets. The intent is to facilitate production of scientifically rigorous results capable of reliable comparisons between and among similar studies. In some cases, the definitions contained here are recommended by consensus of a panel of experts in this writing group for consistency in reporting and publication. These definitions should allow different groups to publish results that are directly comparable.

Reporting Standards for Angioplasty and Stent-Assisted Angioplasty for Intracranial Atherosclerosis

Background and Purpose— Intracranial cerebral atherosclerosis causes ischemic stroke in a significant number of patients. Technological advances over the past 10 years have enabled endovascular treatment of intracranial atherosclerotic stenosis. The number of patients treated with angioplasty or stent-assisted angioplasty for this condition is increasing. Given the lack of universally accepted definitions, the goal of this document is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting clinical and radiological evaluation, technique, and outcome of endovascular treatment using angioplasty or stent-assisted angioplasty for stenotic and occlusive intracranial atherosclerosis.

Summary of Report— This article was written under the auspices of Joint Writing Group of the Technology Assessment Committee, Society of NeuroInterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebrovascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and the Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1997 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data in stenotic intracranial atherosclerosis that could be used as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This document offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of intracranial stenotic and occlusive atherosclerosis. Included in this guidance document are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications.

Conclusion— In summary, the definitions proposed represent recommendations for constructing useful research data sets. The intent is to facilitate production of scientifically rigorous results capable of reliable comparisons between and among similar studies. In some cases, the definitions contained here are recommended by consensus of a panel of experts in this writing group for consistency in reporting and publication. These definitions should allow different groups to publish results that are directly comparable.

Regional or general anesthesia for carotid endarterectomy? Evidence from published prospective and retrospective studies

OBJECTIVES

The aim of this study was to compare outcomes of patients undergoing carotid endarterectomy under regional or general anesthesia for any new neurologic impairment, stroke, stroke and/or death, death, and myocardial infarction.

DESIGN

Meta-analysis.

SETTING

A search of the National Library of Medicine of the United States PUBMED from 1966 up to June 11, 2005, with the following key words: "carotid surgery or endarterectomy and regional anesthesia."

MEASUREMENTS AND MAIN RESULTS

Forty-eight studies (14 prospective and 34 retrospective) were analyzed. The optimal information size was achieved only when all studies were analyzed together (prospective and retrospective). Regional anesthesia reduced the rate of any new neurologic impairment (odds ratio = 0.60; 95% confidence interval, 0.48-0.75; p < 0.00001), stroke (0.54 [0.43-0.68], p < 0.00001), stroke and/or death (0.62 [0.49-0.78], p < 0.0001), death (0.65 [0.48-0.87], p = 0.004), and myocardial infarction (0.50 [0.36-0.70], p < 0.0001).

CONCLUSION

The number of patients included in randomized controlled trials or even in prospective studies is too low to allow any conclusions on the differences in outcome between the 2 anesthetic techniques. Better outcomes are suggested when results from retrospective studies are added.

Reversible cerebral hyperperfusion syndrome after stenting of the carotid artery—Two case reports

Hyperperfusion syndrome can complicate carotid revascularization, be it endarterectomy or carotid artery stenting (CAS). Although extensive effort has been devoted to reducing the incidence of ischemic stroke complicating CAS, little is known about the incidence, etiology, and prevention strategies for hyperperfusion following CAS. We report two cases (female patients 72 and 81 years) presenting severe internal carotid stenosis (> 90%), who underwent presurgical and therapeutic intervention with CAS. Both patients developed hyperperfusion symptoms at 2 hours and at 30 minutes, respectively, following stenting, in both cases unilateral hyperperfusion was CCT confirmed. Case 1 was presenting with acute edema of the right hemisphere, case 2 with distended focal edema (left fronto-temporoparietally). Hyperperfusion syndrome and neurological symptoms retroceded in both cases (conservative therapy) and both patients returned to full activity (case 2 within 48 hours).

Measurement of cerebral reserve capacity using acetazolamide loading xenon CT CBF before carotid endarterectomy

BACKGROUND AND PURPOSE

Brain swelling and/or hemorrhage can occur after carotid endarterectomy. This phenomenon is called the hyperperfusion syndrome. Several factors contribute to this syndrome. One is reperfusion in a maximally dilated vessel which means disappearance of cerebral reserve capacity (CRC). The aim of the study was to determine whether CRC measurement was useful for intraoperative and postoperative management of carotid endarterectomy.

PATIENTS AND METHODS

We studied 64 cases (male 53, female 11), 49-79 years. CRC was measured preoperatively using acetazolamide loading Xenon CT CBF examination (XeCT). Hypothermia (34-35 C) was induced during surgery in a patient with no CRC. Anesthesia was maintained the night after surgery and the systolic blood pressure was controlled below 120 mmHg.

RESULTS

CRC was absent in 10 patients. Postoperative CT did not reveal any hemorrhage or brain swelling. One patient experienced a transient restless state.

DISCUSSION

and conclusions: Cerebral hyperperfusion syndrome has been reported in 0.3 approximately 6.0% of patients following carotid endarterectomy (vs 1.6% in our study without hemorrhage or brain swelling). These data suggest that information on CRC could be useful for selection and perioperative management of patients during carotid endarterectomy.

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.

Identification of Patients at Risk for Ischaemic Cerebral Complications After Carotid Endarterectomy with TCD Monitoring

OBJECTIVES

Transcranial Doppler (TCD) monitoring for micro embolic signals (MES), directly after carotid endarterectomy (CEA) may identify patients at risk of developing ischaemic complications. In this retrospective multicentre study, this hypothesis was investigated.

METHODS

Centres that monitored for MES after CEA were identified by searching Medline. Individual patient data were obtained from centres willing to collaborate. The number of emboli in 1h was computed. Uni- and multivariate logistic regression analyses were performed for the variables gender, age and number of MES. Discriminative ability of MES monitoring was investigated in a ROC curve.

RESULTS

Nine hundred and ninety-one patients were monitored in the first 3h after CEA. Two percent developed ischaemic cerebral complications. Univariate analysis revealed statistically significant associations between ischaemic cerebral complications and both gender and MES, but not age. In a multivariate analysis, > or =8 MES/h showed a statistically significant relationship with cerebral complications (OR 8.1, 95% CI 1.8-36), in contrast to gender (OR 2.2, 95% CI 0.9-5.5). The ROC curve yielded an AUC of 0.83 for monitoring of MES.

CONCLUSIONS

These results support the use of TCD monitoring for MES shortly after CEA in order to identify patients at risk of developing ischaemic cerebral complications.

Hyperperfusion Syndrome after Carotid Endarterectomy

The hyperperfusion syndrome is a rare delayed postoperative complication of carotid endarterectomy (CEA) characterized by headache and seizure, with or without intracranial edema or hemorrhage. Between January 1996 and December 2003, 1,602 CEAs were performed. Six patients (0.4%) developed symptoms of hyperperfusion within 2 weeks of surgery. All patients had critical stenoses, five > or =90% and one 80-90%, with poor backbleeding from the distal internal carotid artery noted at operation in all cases. Five patients were asymptomatic prior to operation; one had a hemispheric transient ischemic attack. Three patients had severe contralateral internal carotid disease (two occlusions and one severe stenosis). Two patients developed severe, self-limiting headache that prolonged hospitalization. Three patients had ipsilateral intracranial bleeding, two occurring after an uneventful postoperative course. After initial discharge from the hospital, severe intracranial hemorrhage caused death in two patients. One patient experienced focal seizures 1 week after discharge. Hypertension did not appear to be related to the symptoms in any case. During the study period, the hyperperfusion syndrome caused three of five perioperative strokes (60%) and two of seven deaths (29%) in the entire endarterectomy population. Although rare, the hyperperfusion syndrome accounts for a significant percentage of the neurological morbidity and mortality following CEA.

Transcranial Doppler Monitoring after Carotid Endarterectomy

The objectives of this study were to evaluate the feasibility of transcranial Doppler (TCD) monitoring after carotid endarterectomy (CEA) and to investigate whether 1 hr of monitoring is sufficient to detect a clinically relevant change in the number of postoperative microemboli. We also evaluated the association of patient characteristics and procedure-related variables with the number of postoperative microemboli. One hundred and two patients were monitored during the second hour after CEA. The main outcome measure was the number of TCD-detected microemboli. The secondary outcome measure was a procedure-related cerebral complication graded according to the modified Rankin scale. The median number of microemboli during the second postoperative hour was two (interquartile ranges, 0.75-11) and decreased in most the patients during this time. Two patients had a relatively high and increasing number of microemboli and developed a minor stroke after a symptom-free interval. One patient developed a TIA intraoperatively. There was no significant association between patient characteristics and the use of a venous patch and the number of postoperative microemboli. Conversely, a statistically significant negative association was found between shunt use and the number of microemboli (p = 0.02). The majority of patients had no or a small and decreasing number of microemboli. One hour of monitoring appeared to be effective to select those patients in whom the number of microemboli did not spontaneously decrease and who may need additional medical treatment or surgical reexploration. The role of TCD-detected microemboli as a surrogate measure for the risk of stroke after CEA remains to be validated.

[Intraoperative detection of ischemic brain hypoxia using oxygen tissue pressure microprobes]

OBJECTIVE AND IMPORTANCE

Detection of intraoperative ischemic events could lead to the resolution of their cause and to the prevention of the definitive establishment of a postoperative infarct. We want to illustrate the possibilities that intraoperative monitoring of oxygen tissue pressure (PtiO2) in critical areas during a neurosurgical vascular procedure offers, enhancing its reliability and immediacy in obtaining information about tissue oxygenation status as a marker of ischemia in the vascular territory at risk.

CLINICAL PRESENTATION

We report the case of a 32 year-old male with a deep arteriovenous malformation (AVM) localised in the insular region. The patient had been previously treated with radiosurgery without achieving a satisfactory result.

INTERVENTION

AVM removal was performed through a transylvian transinsular approach. PtiO2 was monitorised at the temporal pole (reference area) and at the posterior temporal region (risk area). Both probes maintained close tissue oxygenation levels until the last stage of the AVM resection when, during the coagulation of a supposed afferent vessel, a brisk fall of the oxygen tissue pressure in the posterior temporal region was detected. An ischemic infarct in this area was observed postoperatively.

CONCLUSIONS

PtiO2 monitoring has a high reliability in the detection of intraoperative tissue hypoxia. Data obtained could lead to early identification of these events and, whatever possible, to resolve this situation preventing the definitive establishment of an ischemic infarct.

Hyperperfusion Syndrome: Toward a Stricter Definition

OBJECTIVE

Hyperperfusion syndrome is a rare and potentially devastating complication of carotid endarterectomy or carotid artery angioplasty and stenting. With the advent of new imaging techniques, we reviewed our experience with this phenomenon.

METHODS

This report is a retrospective review of 129 consecutive cases of carotid endarterectomy performed between June 1, 2000, and May 31, 2002, and 44 consecutive cases of carotid artery angioplasty and stenting performed between January 1, 1997, and May 31, 2002. We specifically searched for examples of patients who developed postprocedural nonthrombotic neurological deficits that typified the hyperperfusion syndrome.

RESULTS

Seven cases of hyperperfusion syndrome occurred, four after endarterectomy (3.1% of carotid endarterectomy cases) and three after stenting (6.8% of stenting cases). The cases of hyperperfusion were classified as presenting with 1) acute focal edema (two cases with stroke-like presentation, attributable to edema immediately after revascularization), 2) acute hemorrhage (two cases of intracerebral hemorrhage immediately after stenting and one case immediately after endarterectomy), or 3) delayed classic presentation (two cases with seizures, focal motor weakness, and/or late intracerebral hemorrhage at least 24 hours after endarterectomy).

CONCLUSION

Hyperperfusion syndrome may be more common and more variable in clinical presentation than previously appreciated.

Ipsilateral intracerebral hemorrhage following carotid stent-assisted angioplasty: a manifestation of hyperperfusion syndrome--a case report

A case of hyperperfusion syndrome manifested as intracerebral hemorrhage following carotid stent-assisted angioplasty while using intravenous abciximab is described. Review of literature regarding hyperperfusion syndrome in patients undergoing carotid artery revascularization is presented. Possible mechanisms of hyperperfusion and the role of arterial hypertension, anticoagulation, and antiplatelet treatment in the genesis of hyperperfusion syndrome are discussed. Widening use of percutaneous carotid revascularization necessitates physicians' awareness of early recognition of this complication.

Transcranial Doppler in carotid endarterectomy

PURPOSE

To evaluate the role of transcranial Doppler monitoring in reducing the complications of carotid endarterectomy, by analysing: (1) perioperative intracerebral blood flow velocity; (2) embolic load; and (3) effect of Dextran-40 therapy on patient outcome.

DESIGN

Retrospective case series.

METHODS

The study cohort consisted of 30 consecutive patients undergoing 32 carotid endarterectomy procedures. Continuous transcranial Doppler (TCD) monitoring of the ipsilateral middle cerebral artery (MCA) was performed to obtain flow velocities and embolic count. Flow velocity changes were analysed in relation to electroencephalographic (EEG) changes. A Dextran-40 infusion was instituted for patients who experienced a post-arteriotomy embolic load of >50 counts/hour.

RESULTS

The average middle cerebral artery velocity (MCAvel) drop on cross clamping was 46+/-12.1%, expressed as a percentage of the individual's 24-hour pre-operative value. Clamping ischaemia developed in six cases (18.8%) of which three (9.4%) demonstrated TCD changes only, and three demonstrated both TCD and EEG changes (9.4%). The average increase in MCAvel at 60-120 minutes postarteriotomy, was 18+/-17.5%; six cases developed hyperaemia. Postoperative emboli were seen in 88% of cases with 31% of patients demonstrating embolic loads of >50/hour.

CONCLUSIONS

Perioperative transcranial Doppler monitoring (1) is a useful adjunct to EEG assessment of cross clamping ischaemia, providing information in real time, on MCA blood velocity deterioration that may antecede irreversible change (2) detects postoperative hyperaemic response, and (3) allows quantification of microembolic loads that, when high, have been shown to be a precursor to localised cerebral ischaemia and can be effectively treated with Dextran-40 infusion.

Flow redistribution in the major cerebral arteries after carotid endarterectomy: a study with transcranial Doppler scan

PURPOSE

This open single-center prospective study aimed to determine the redistribution of blood flow within the circle of Willis and through collateral pathways after carotid endarterectomy. Blood flow velocity and flow direction in the major cerebral arteries were determined, both at rest and during CO(2) inhalation.

METHODS

Carotid endarterectomy was performed in 148 patients with a 70% or greater diameter stenosis of the internal carotid artery while patients were under general anesthesia. Arteriotomy closure was done with a venous patch. Selective shunting was performed with an electroencephalogram. Baseline blood flow velocity of the basal cerebral arteries was measured by means of transcranial Doppler sonography preoperatively (within 1 week before surgery) and 3 months postoperatively. At the same times, cerebrovascular reactivity was calculated during CO(2) inhalation insonating both middle cerebral arteries.

RESULTS

Baseline blood flow velocity in the ipsilateral middle cerebral artery hardly changed 3 months postoperatively, but there was a considerable redistribution of flow in the circle of Willis. This was characterized by a decrease in contribution from the contralateral hemisphere through the anterior communicating artery, reduced cerebropetal flow rates in the ophthalmic artery, and smaller contribution of the posterior collateral sources. The CO(2) reactivity on the side of surgery increased in all patients. In patients with a contralateral occlusion, CO(2) reactivity increased on both sides. The redistribution of flow was most pronounced in patients who needed intraoperative shunting and in patients with a contralateral internal carotid artery occlusion.

CONCLUSION

After carotid endarterectomy, flow redistribution, as expressed by changes in blood flow velocity values, occurs in the circle of Willis. The contribution of collateral sources is diminished, and the CO(2) reactivity increases, both of which reflect improvement of the hemodynamic condition. The most improvement occurs in patients with contralateral occlusion.

Cerebral hyperperfusion syndrome after percutaneous transluminal stenting of the craniocervical arteries

OBJECTIVE

Cerebral hyperperfusion syndrome is a recognized complication of carotid endarterectomy, with a reported incidence of 0.3 to 1.2%. The incidence of cerebral hyperperfusion after endovascular revascularization procedures of the craniocervical arteries remains unknown. We evaluated the incidence of cerebral hyperperfusion syndrome in our endovascular revascularization series. To our knowledge, there are no previous studies evaluating the incidence of hyperperfusion syndrome after percutaneous transluminal angioplasty/stenting.

METHODS

Between March 1996 and February 2000, 140 patients underwent percutaneous transluminal angioplasty/stenting of the craniocervical arteries at our institution. In all patients, selective bilateral arteriography of the carotid and vertebral arteries was performed to document the sites of craniocervical stenosis and collateral blood flow and the results of the endovascular revascularization procedure. We then reviewed all pertinent medical records, arteriographic films, and sectional imaging studies to determine the incidence of cerebral hyperperfusion in this series.

RESULTS

Seven patients (5.0%) developed clinical or radiological manifestations of cerebral hyperperfusion. In the target group, percutaneous transluminal stenting achieved a 90 to 100% reduction in stenotic lesions (mean stenosis, 91%) of the carotid (n = 5) and vertebral (n = 2) arteries. All seven patients remained neurologically stable immediately after treatment. There was delayed development of clinical and radiographic findings, suggestive of cerebral hyperperfusion. Six patients showed evidence of ipsilateral hemispheric edema, including two patients who developed intracranial hemorrhage (one parenchymal, one parenchymal and subarachnoid) documented by computed tomographic brain scans. Symptoms resolved within 72 hours in the four patients without hemorrhage. The two patients with hemorrhage recovered during a more protracted period (range, 3 wk to 6 mo). There were no long-term sequelae or deaths during a cumulative follow-up of 84 months (mean follow-up, 12 mo).

CONCLUSION

Hyperperfusion syndrome is an uncommon but potentially serious complication of extracranial and intracranial angioplasty and stenting procedures. The clinical manifestations are similar to hyperperfusion syndrome after carotid endarterectomy; however, the prevalence may be greater in the high-risk cohort commonly referred for endovascular treatment. Our findings suggest that patients undergoing endovascular stenting procedures should be closely monitored for evidence of hyperperfusion, with careful monitoring of blood pressure, heart rate, and anticoagulation. Further research is needed to confirm that cerebral hyperperfusion is the pathogenesis of this condition.

Silent cerebral ischemia detected by diffusion-weighted MRI after carotid endarterectomy

BACKGROUND AND PURPOSE

Small emboli arising from a friable plaque during carotid endarterectomy (CEA) constitute an important risk of perioperative ischemic complications. To evaluate the incidence and significance of silent cerebral ischemic lesions of embolic origin after CEA, we prospectively examined a series of surgical patients with high-grade carotid stenosis by using diffusion-weighted MRI (DWI). We also tried to correlate postoperative ischemic lesions with the occurrence of sonographic cerebral embolic signals, the presence of plaque ulcerations, and the use of intraoperative shunting.

METHODS

Of a consecutive series of 53 patients undergoing elective CEA for high-grade carotid stenosis, 48 patients with unchanged postoperative neurological status were prospectively studied with DWI of the brain the day before and the day after the operation. The magnetic resonance images were analyzed by 2 neuroradiologists blinded to the clinical result of the operation. Any new hyperintense signal was interpreted as a postoperative ischemic lesion.

RESULTS

Forty-six (95.8%) of 48 patients had unchanged postoperative brain DWI. In 2 patients (4.2%), a new single asymptomatic hyperintense signal was observed on the side of the operation. Both lesions were small and presumably of embolic origin. They were not related to sonographic embolic signals, plaque ulcerations, or intraoperative shunting.

CONCLUSIONS

These results suggest that the incidence of silent ischemic brain lesions of embolic origin after CEA is low and does not correlate with the occurrence of intraoperative sonographic microemboli. They confirm that CEA is a safe procedure that carries a low risk of postoperative cerebral events.

Anesthesia for carotid endarterectomy

Patients presenting for carotid endarterectomy provide anesthesiologists with many challenges. These include optimization of cerebrovascular hemodynamics and oxygen balance, as well as minimizing myocardial risk. Fiscal pressures have encouraged the development of clinical pathways in many centers, with a remarkable trend towards decreased intensive care unit utilization and length of hospital stay. Anesthetic and surgical practices vary widely, but outcomes in these high-risk patients are usually excellent despite these differences. The potential for expanded indications for carotid endarterectomy and development of percutaneous treatment for carotid stenosis will provide neurovascular anesthesiologists with additional incentives to refine the anesthetic management of these patients.