Defective cerebrovascular autoregulation after carotid endarterectomy

Redefining postoperative hypertension management in carotid surgery: a comprehensive analysis of blood pressure homeostasis and hyperperfusion syndrome in unilateral vs. bilateral carotid surgeries and implications for clinical practice

Background

This study evaluates the implications of blood pressure homeostasis in bilateral vs. unilateral carotid surgeries, focusing on the incidence of postoperative hypertension, hyperperfusion syndrome, and stroke as primary outcomes. It further delves into the secondary outcomes encompassing major adverse cardiovascular events and all-cause mortality.

Methods

Spanning two decades (2002-2023), this comprehensive retrospective research encompasses 15,369 carotid referrals, out of which 1,230 underwent carotid interventions. A subset of 690 patients received open carotid procedures, with a 10-year follow-up, comprising 599 unilateral and 91 bilateral surgeries. The Society for Vascular Surgery Carotid Reporting Standards underpin our methodological approach for data collection. Both univariate and multivariate analyses were utilized to identify factors associated with postoperative hypertension using the Statistical Package for the Social Sciences (SPSS) Version 22 (SPSS®, IBM® Corp., Armonk, N.Y., USA).

Results

A marked acute elevation in blood pressure was observed in patients undergoing both unilateral and bilateral carotid surgeries (p < 0.001). Smoking (OR: 1.183, p = 0.007), hyperfibrinogenemia (OR: 0.834, p = 0.004), emergency admission (OR: 1.192, p = 0.005), severe ipsilateral carotid stenosis (OR: 1.501, p = 0.022), and prior ipsilateral interventions (OR: 1.722, p = 0.003) emerged as significant factors that correlates with postoperative hypertension in unilateral surgeries. Conversely, in bilateral procedures, gender, emergency admissions (p = 0.012), and plaque morphology (p = 0.035) significantly influenced postoperative hypertension. Notably, 2.2% of bilateral surgery patients developed hyperperfusion syndrome, culminating in hemorrhagic stroke within 30 days. Intriguingly, postoperative stage II hypertension was identified as an independent predictor of neurological deficits post-secondary procedure in bilateral CEA cases (p = 0.004), attributable to hyperperfusion syndrome. However, it did not independently predict myocardial infarction or mortality outcomes. The overall 30-day stroke rate stood at 0.90%. Lowest incidence of post operative hypertension or any complications were observed in eversion carotid endartrertomy.

Conclusion

The study identifies postoperative hypertension as a crucial independent predictor of perioperative stroke following bilateral carotid surgery. Moreover, the study elucidates the significant impact of bilateral CEA on the development of post-operative hyperperfusion syndrome or stroke, as compared to unilateral CEA. Currently almost 90% of our carotid practice is eversion carotid endartrerectomy.

An uncommon case of nonconvulsive status epilepticus successfully treated with enteral Brivaracetam

BACKGROUND AND AIM OF THE WORK

We present a case of a woman affected by nonconvulsive status epilepticus (NCSE) caused by cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) who was successfully treated with Brivaracetam (BRV) administered via nasogastric tube (NGT).

CASE PRESENTATION

An 82-years old woman was referred for increasing blood pressure, severe headache and two focal motor seizures on postoperative day four after right CEA. CT scan showed edema of the right hemisphere with a midline shift of 5 mm. The patient underwent daily Electroencephalography (EEG) monitoring which showed continuous epileptiform discharges over the right hemisphere, compatible with a diagnosis of status epilepticus. She was treated with standard antiepileptic drugs (Phenytoin, Lacosamide and Levetiracetam iv) without clinical response. A therapeutic trial with BRV 200mg administered via nasogastric tube (NGT) was tried which resulted in substantial clinical benefit.

CONCLUSIONS

The administration of new antiepileptic drugs (AEDs) such as BRV may result in significant clinical improvement in refractory cases of status epilepticus. The enteral administration of AEDs via NGT should always be considered for refractory cases of status epilepticus when standard iv treatment has failed or is not possible.

Staged angioplasty versus regular carotid artery stenting in patients with carotid artery stenosis at high risk of hyperperfusion: a randomised clinical trial

Background and purpose

Hyperperfusion (HP) is a devastating complication associated with carotid artery stenting (CAS) or endarterectomy. The efficacy and safety of staged angioplasty (SAP) in patients with CAS at high risk of HP remains unclear. We sought to determine whether SAP is superior to regular CAS in patients with high risk of HP.

Methods

A randomised, multicentre open-label clinical trial with blinded outcome assessment (STEP) was conducted. Patients with severe carotid stenosis at high risk of HP were randomly assigned (1:1) to the SAP or regular CAS group. The primary endpoint was hyperperfusion syndrome (HPS) and intracerebral haemorrhage (ICH) within 30 days after the procedure.

Results

From November 2014 to January 2017, a total of 64 patients were enrolled in 11 centres. 33 patients were allocated to the SAP group and 31 to the regular CAS group. At 30 days, the rate of primary endpoint was 0.0% (0/33) in the SAP group and 9.7% (3/31) in the regular CAS group (absolute risk reduction (ARR), 9.7%; 95% CI −20.1% to 0.7%; p=0.11). As one of the secondary endpoints, the incidence of HP phenomenon (HPP) was lower in the SAP group than the regular CAS group (0.0% vs 22.6%, ARR,−22.6%; 95% CI −36.8% to −10.2%; p=0.04).

Conclusion

The rate of HPS and ICH was not significantly lower in SAP group; the extended secondary endpoint of HPP, however, significantly reduced, which suggested that SAP may be a safe and effective carotid revascularisation procedure to prevent HP.

Trial registration number

NCT02224209.

Cerebral Hemodynamic Evaluation After Cerebral Recanalization Therapy for Acute Ischemic Stroke

Cerebral recanalization therapy, either intravenous thrombolysis or mechanical thrombectomy, improves the outcomes in patients with acute ischemic stroke (AIS) by restoring the cerebral perfusion of the ischemic penumbra. Cerebral hemodynamic evaluation after recanalization therapy, can help identify patients with high risks of reperfusion-associated complications. Among the various hemodynamic modalities, magnetic resonance imaging (MRI), computed tomography perfusion, and transcranial Doppler sonography (TCD) are the most commonly used. Poststroke hypoperfusion is associated with infarct expansion, while hyperperfusion, which once was considered the hallmark of successful recanalization, is associated with hemorrhagic transformation. Either the hypo- or the hyperperfusion may result in poor clinical outcomes. Individual blood pressure target based on cerebral hemodynamic evaluation was crucial to improve the prognosis. This review summarizes literature on cerebral hemodynamic evaluation and management after recanalization therapy to guide clinical decision making.

Effectiveness of staged angioplasty for avoidance of cerebral hyperperfusion syndrome after carotid revascularization

OBJECTIVE

Cerebral hyperperfusion syndrome (CHS) is a serious complication after carotid artery stenting (CAS). Staged angioplasty (SAP)-i.e., angioplasty followed by delayed CAS-has been reported as a potential CHS-avoiding procedure. The purpose of this study was to clarify the effectiveness of SAP in avoiding CHS after carotid revascularization for patients at high risk for this complication.

METHODS

The authors retrospectively studied cases involving patients at high risk for CHS from 44 Japanese centers who were scheduled for SAP, regular CAS, angioplasty, or staged procedures other than SAP between October 2007 and March 2014. They investigated the rate of CHS in the population scheduled for SAP or regular CAS, and for safety analysis, the composite rate of transient ischemic attack (TIA) and ischemic stroke in the population eventually receiving SAP or regular CAS.

RESULTS

Data from a total of 525 patients (532 lesions, mean age 72.5 ± 7.5 years, 74 women ) were analyzed. Scheduled procedures included SAP for 113 lesions and regular CAS for 419 lesions. The rate of CHS was lower in the SAP group than in the regular CAS group (4.4% vs 10.5%, p = 0.047). Multivariate analysis showed that SAP was negatively related to CHS (OR 0.315; 95% CI 0.120-0.828). In the population eventually receiving SAP (102 lesions) or regular CAS (428 lesions), the composite rate of TIA and ischemic stroke was comparable between the SAP group and the regular CAS group (9.8% vs 9.3%).

CONCLUSIONS

SAP may be an effective and safe carotid revascularization procedure to avoid CHS.

Reperfusion Changes After Stroke and Practical Approaches for Neuroprotection

Reperfusion is the first line of care in a growing number of eligible acute ischemic stroke patients. Early reperfusion with thrombolytic drugs and endovascular mechanical devices is associated with improved outcome and lower mortality rates compared with natural history. Reperfusion is not without risk, however, and may result in reperfusion injury, which manifests in hemorrhagic transformation, brain edema, infarct progression, and neurologic worsening. In this article, the functional and structural changes and underlying molecular mechanisms of ischemia and reperfusion are reviewed. The pathways that lead to reperfusion injury and novel neuroprotective strategies with endogenous properties are discussed.

TLR2 knockout protects against diabetes-mediated changes in cerebral perfusion and cognitive deficits

The risk of cognitive decline in diabetes (Type 1 and Type 2) is significantly greater compared with normoglycemic patients, and the risk of developing dementia in diabetic patients is doubled. The etiology for this is likely multifactorial, but one mechanism that has gained increasing attention is decreased cerebral perfusion as a result of cerebrovascular dysfunction. The innate immune system has been shown to play a role in diabetic vascular complications, notably through the Toll-like receptor (TLR)-stimulated release of proinflammatory cytokines and chemokines that lead to vascular damage. TLR2 has been implicated in playing a crucial role in the development of diabetic microvascular complications, such as nephropathy, and thus, we hypothesized that TLR2-mediated cerebrovascular dysfunction leads to decreased cerebral blood flow (CBF) and cognitive impairment in diabetes. Knockout of TLR2 conferred protection from impaired CBF in early-stage diabetes and from hyperperfusion in long-term diabetes, prevented the development of endothelium-dependent vascular dysfunction in diabetes, created a hyperactive and anxiolytic phenotype, and protected against diabetes-induced impairment of long-term hippocampal and prefrontal cortex-mediated fear learning. In conclusion, these findings support the involvement of TLR2 in the pathogenesis of diabetic vascular disease and cognitive impairment.

Neurologic complications of cardiac and vascular surgery

This chapter will provide an overview of the major neurologic complications of common cardiac and vascular surgeries, such as coronary artery bypass grafting and carotid endarterectomy. Neurologic complications after cardiac and vascular surgeries can cause significant morbidity and mortality, which can negate the beneficial effects of the intervention. Some of the complications to be discussed include ischemic and hemorrhagic stroke, seizures, delirium, cognitive dysfunction, cerebral hyperperfusion syndrome, cranial nerve injuries, and peripheral neuropathies. The severity of these complications can range from mild to lethal. The etiology of complications can include a variety of mechanisms, which can differ based on the type of cardiac or vascular surgery that is performed. Our knowledge about neuropathology, prevention, and management of surgical complications is growing and will be discussed in this chapter. It is imperative for clinicians to be familiar with these complications in order to narrow the differential diagnosis, start early management, anticipate the natural history, and improve outcomes.

Signal changes on magnetic resonance perfusion images with arterial spin labeling after carotid endarterectomy

BACKGROUND

Cerebral hyperperfusion after carotid endarterectomy (CEA) is defined as an increase in ipsilateral cerebral blood flow (CBF). Practically, however, prompt and precise assessment of cerebral hyperperfusion is difficult because of limitations in the methodology of CBF measurement during the perioperative period. Arterial spin labeling (ASL) is a completely noninvasive and repeatable magnetic resonance perfusion imaging technique that uses magnetically-labelled blood water as an endogenous tracer. To clarify the usefulness of ASL in the management of cerebral hyperperfusion, we investigated signal changes by ASL with a single 1.5-s post-labeling delay on visual inspection.

METHODS

Thirty-two consecutive patients who underwent CEA were enrolled in this retrospective study.

RESULTS

On postoperative day 1, 22 (68.8%) and 4 (12.5%) patients exhibited increased ASL signals bilaterally (Group A) and on the operated side (Group B), respectively. Follow-up ASL showed improvement in these findings. Six (18.8%) patients showed no change (Group C). There was no apparent correlation between ASL signals on postoperative day 1 and the preoperative hemodynamic state, including the cerebrovascular reserve (P = 0.2062). Three (9.4%) patients developed cerebral hyperperfusion syndrome (two in Group A and one in Group B). Coincidence in the localization of increased ASL signals and electroencephalographic abnormalities was noted in these patients.

CONCLUSION

Visual analysis of ASL with a single post-labeling delay overestimates CBF and cannot identify patients at risk of cerebral hyperperfusion syndrome probably because of the strong effect of the shortened arterial transit time immediately after CEA. However, ASL may be used as for screening.

Cerebral Hyperperfusion Syndrome

Cerebral reperfusion following carotid endarterectomy occasionally causes cerebral hyperperfusion syndrome. This is a rare but important complication and this case report acted as a stimulus for a literature review of this problem.

A 60-year-old businessman had a right carotid endarterectomy for a severe stenosis which had caused recurrent attacks of amaurosis fugax. The left internal carotid artery had occluded asymptomatically. The operation and his immediate postoperative recovery were entirely uneventful but he developed right-sided headaches and focal sensory motor seizures. He subsequently recovered.

Hemodynamically compromised patients appear to be at greater risk and as the mortality of the operation is reduced and more complex patients are treated, it is likely that this unusual complication will increase in incidence.

Prediction of Cerebral Hyperperfusion Syndrome with Velocity Blood Pressure Index

Background:

Cerebral hyperperfusion syndrome is an important complication of carotid endarterectomy (CEA). An >100% increase in middle cerebral artery velocity (MCAV) after CEA is used to predict the cerebral hyperperfusion syndrome (CHS) development, but the accuracy is limited. The increase in blood pressure (BP) after surgery is a risk factor of CHS, but no study uses it to predict CHS. This study was to create a more precise parameter for prediction of CHS by combined the increase of MCAV and BP after CEA.

Methods:

Systolic MCAV measured by transcranial Doppler and systematic BP were recorded preoperatively; 30 min postoperatively. The new parameter velocity BP index (VBI) was calculated from the postoperative increase ratios of MCAV and BP. The prediction powers of VBI and the increase ratio of MCAV (velocity ratio [VR]) were compared for predicting CHS occurrence.

Results:

Totally, 6/185 cases suffered CHS. The best-fit cut-off point of 2.0 for VBI was identified, which had 83.3% sensitivity, 98.3% specificity, 62.5% positive predictive value and 99.4% negative predictive value for CHS development. This result is significantly better than VR (33.3%, 97.2%, 28.6% and 97.8%). The area under the curve (AUC) of receiver operating characteristic: AUC_VBI= 0.981, 95% confidence interval [CI] 0.949–0.995; AUC_VR= 0.935, 95% CI 0.890–0.966, P = 0.02.

Conclusions:

The new parameter VBI can more accurately predict patients at risk of CHS after CEA. This observation needs to be validated by larger studies.

Hyperperfusion syndrome after MCA embolectomy - a rare complication?

Patient: Female, 78

Final Diagnosis: Cerebral hyperperfusion syndrome

Symptoms: —

Medication: —

Clinical Procedure: Endovascular embolectomy

Specialty: Neurology

Post-carotid endarterectomy cerebral hyperperfusion syndrome : is it preventable by strict blood pressure control?

Objective

Cerebral hyperperfusion syndrome (CHS) is a serious complication after carotid endarterectomy (CEA). However, the prevalence of CHS has decreased as techniques have improved. This study evaluates the role of strict blood pressure (BP) control for the prevention of CHS.

Methods

All 18 patients who received CEA from February 2009 through November 2012 were retrospectively reviewed. All patients were routinely managed in an intensive care unit by a same protocol. The cerebral perfusion state was evaluated on the basis of the regional cerebral blood flow (rCBF) study by perfusion computed tomography (pCT) and mean velocity by transcranial doppler (TCD). BP was strictly controlled (<140/90 mm Hg) for 7 days. When either post-CEA hyperperfusion (>100% increase in the rCBF by pCT or in the mean velocity by TCD compared with preoperative values) or CHS was detected, BP was maintained below 120/80 mm Hg.

Results

TCD and pCT data on the patients were analyzed. Ipsilateral rCBF was significantly increased after CEA in the pCT (p=0.049). Post-CEA hyperperfusion was observed in 3 patients (18.7%) in the pCT and 2 patients (12.5%) in the TCD study. No patients developed clinical CHS for one month after CEA. Furthermore, no patients developed additional neurological deficits related to postoperative cerebrovascular complications.

Conclusion

Intensive care with strict BP control (<140/90 mm Hg) achieved a low prevalence of post-CEA hyperperfusion and prevented CHS. This study suggests that intensive care with strict BP control can prevent the prevalence of post-CEA CHS.

Hyperperfusion syndrome after carotid endarterectomy and carotid stenting

BACKGROUND

Hyperperfusion syndrome (HS) is a relatively rare but possibly serious complication of carotid revascularization procedures. Impaired cerebral autoregulation and postrevascularization changes in cerebral blood flow are the main mechanisms involved in the development of HS. Most up-to-date studies addressing this issue are retrospective and tend to concentrate on carotid endarterectomy (CEA), neglecting carotid stenting (CAS). Our aim was to compare the frequency of clinical signs of HS and hyperperfusion detected by transcranial Doppler (TCD) in patients undergoing CAS or CEA due to carotid stenosis.

METHODS

In this prospective observational study, we evaluated 61 patients scheduled for routine CAS or CEA. Each patient was examined by a neurologist before and after the revascularization procedure to assess the clinical status. Severe headache, ocular or facial pain, confusion, visual disturbances, epileptic seizures or any focal deficits not caused by cerebral ischemia were considered clinical signs of HS. Peak systolic velocity (PSV), end-diastolic velocity, mean velocity (MV), and pulsatility index were measured by TCD once before and twice after the intervention (within 6 h after and 2-5 days after the procedure). Hyperperfusion was defined as a >100% increase in the middle cerebral artery (MCA) blood velocity, evaluated separately for PSV and MV after the procedure compared with the baseline value. Cerebrovascular reactivity (CVR) was evaluated with a TCD acetazolamide test before the intervention.

RESULTS

CAS (n = 33) and CEA (n = 28) patients were included in the study. There was no difference between the groups in the frequency of clinical signs of HS (21.2 vs. 21.4%) and ratio of TCD hyperperfusion (12.1 vs. 14.3%). In the CAS group, ipsilateral MCA velocity significantly increased directly after the intervention and 2-5 days later, while it increased in the CEA group only 2-5 days after the intervention. The sensitivity and specificity of hyperperfusion, defined by MV, for HS signs were 38.5 and 93.8%, respectively, whereas those defined by PSV were 30.8 and 89.6%, respectively. The sensitivity and specificity of impaired CVR (<25%) for HS signs were 63.6 and 73.5%, respectively.

CONCLUSIONS

There is no difference in the frequency of HS clinical signs and hyperperfusion detected by TCD between patients after CAE and CAS. Clinical signs suggested HS does not always correspond with TCD hyperperfusion. However, both the CVR test and TCD measurements of MCA velocity can help identify patients at high risk for HS.

Seizures and the neurosurgical intensive care unit

The cause of seizures in the neurosurgical intensive care unit (NICU) can be categorized as emanating from either a primary brain pathology or from physiologic derangements of critical care illness. Patients are typically treated with parenteral antiepileptic drugs. For early onset ICU seizures that are easily controlled, data support limited treatment. Late seizures have a more ominous risk for subsequent epilepsy and should be treated for extended periods of time or indefinitely. This review ends by examining the treatment algorithms for simple seizures and status epilepticus and the role newer antiepileptic use can play in the NICU.

Changes in middle cerebral artery velocity after carotid endarterectomy do not identify patients at high-risk of suffering intracranial haemorrhage or stroke due to hyperperfusion syndrome

OBJECTIVES

To determine if significant increases in middle cerebral artery velocity (MCAV) or pulsatility index (PI) during and immediately after carotid endarterectomy (CEA) were predictive of patients suffering a stroke due to the hyperperfusion syndrome (HS) or intracerebral haemorrhage (ICH).

METHODS

Transcranial Doppler (TCD) mean/peak MCAV and PI were recorded pre-operatively; pre-clamp; 1-min post-declamping; 10-min post-declamping and 30-min post-operatively. The study was divided into two time periods; Group 1 (1995-2007); where there was no formal guidance for managing post-CEA hypertension (PEH) and Group 2 (2008-2012); where written guidelines for treating PEH were available.

RESULTS

11/1024 patients in Group 1 (1.1%) suffered a stroke due to HS/ICH, compared to 0/426 patients (0.0%) in Group 2 (p = 0.02). In Group 1; intra-operative increases >100% in mean/peak MCAV and PI at 1 and 10-min post-clamp release had positive predictive values (PPV) of 1.2%, 6.3% and 20.0% and 2.9%, 8.0% and 16.6% respectively. Post-operatively; a >100% increase in mean and peak MCAV had a PPV of 6.3% and 2.7% respectively.

CONCLUSION

We were unable to demonstrate that significant increases in MCAV and PI were able to predict patients at increased risk of suffering a post-operative stroke due to HS or ICH. The provision of written guidance for managing PEH in Group 2 patients was associated with virtual abolition of ICH/HS.

Improved parameterization of the transcranial Doppler signal

The great potential of transcranial Doppler (TCD) as a tool for neuromonitoring is limited by the current parameterization of the signal. This article proposes a set of new parameters that more accurately represents the shape of the waveform and eliminates a number of confounding factors. This set of parameters was tested in 227 patients with ipsilateral carotid artery stenosis and compared with 31 normal subjects recruited at our laboratory. From the TCD waveform, we calculated on a beat-to-beat basis the maximal change in flow velocity at stroke onset (acceleration or acc), the maximal flow velocity during the first 100 ms of systole (sys1) and the maximal flow velocity in the remaining part of systole (sys2). All data were normalized relative to the mean diastolic flow velocity over an interval ranging from 520 till 600 ms after stroke onset (dias@560). For the group with carotid stenosis compared with the normal controls the average ± SD for acc (20.2 ± 9.5 vs. 20.2 ± 6.7; p = 0.98) and sys1 (1.82 ± 0.38 vs. 1.77 ± 0.56; p = 0.35) did not differ significantly. The average ±SD for sys2 (1.94 ± 0.33 vs. 1.50 ± 0.12; p < 0.001), however, was significantly higher in the group with carotid stenosis than in the group of normal subjects. The difference between sys1 and sys2 ("sys1-sys2") was lower in the patient group than in controls (-0.12 ± 0.16 vs. 0.27 ± 0.22; p < 0.001). For the acc, there was a significantly higher variance in the group with stenosis than without (p < 0.001). Of the old parameters, the beat-to-beat mean (37.0 ± 13.1 vs. 41.3 ± 15.9; p = 0.17) and the pulsatility index (PI; 1.00 ± 0.26 vs. 0.91 ± 0.23; p = 0.06) were not significantly different between groups. Graphed together the acc and "sys1-sys2" parameters allowed a clear demarcation of both groups whereas in a graph of the old parameters mean and PI both groups overlapped considerably. In conclusion, the proposed set of new parameters not only has theoretical and practical benefits but also has excellent discriminative power in a group of carotid patients compared with normal controls.

Cerebral hyperperfusion syndrome after carotid intervention: a review

Cerebral hyperperfusion syndrome (CHS) after carotid surgery, although rare, is a well-described phenomenon. Although originally described after carotid endarterectomy, it has now also been described after carotid artery stenting. It is classically described as an acute neurologic deficit occurring several days after a carotid procedure, associated with severe hypertension and preceded by a severe headache. CHS represents a spectrum of clinical symptoms ranging from severe unilateral headache, to seizures and focal neurologic defects, to intracerebral hemorrhage in its most severe form. The exact mechanism leading to CHS is unknown; however, it seems to be related to increased regional cerebral blood flow secondary to loss of cerebrovascular autoregulation. Given the significant morbidity associated with CHS, researchers have been trying to identify which patients are most at risk. This is a difficult task given the rarity of the disease and the multiple confounding factors in the patient population who undergo carotid intervention. The goal was to determine those patients most at risk preoperatively, so that they may be more closely monitored postoperatively to prevent the development of CHS and its associated morbidity. The purpose of this review was to summarize the data currently available in the literature on CHS, with emphasis on pathophysiology, risk factor assessment, diagnostic modalities, and disease management, to provide insight for future research to better elucidate how to reduce the morbidity and mortality caused by CHS.

Short- and long-term hemodynamic and clinical effects of carotid artery stenting

BACKGROUND AND PURPOSE

Stenosis of the carotid artery may cause reduced hemodynamic and neural function that may be ameliorated with CAS. The goal of this study was to evaluate short- and long-term hemodynamic and clinical effects after CAS.

MATERIALS AND METHODS

Hemodynamic parameters were acquired by PCT within 1 week before CAS and at 1 week and 1 year (10-13 months) after CAS. In ACA territory, MCA territory, PCA territory, basal ganglia, anterior and posterior CWS and IWS, the rCBF, rCBV, and rMTT were determined in 20 patients with unilateral carotid artery stenosis who underwent CAS. MR and noncontrast CT were performed within 1 week before CAS. Noncontrast CT and carotid arteriography were performed immediately after CAS. Carotid arteriography was performed 1 year after CAS. MRS was performed in 3 measurements. The variance analysis was performed to determine whether there were significant differences among the 3 measurements.

RESULTS

No significant differences were found among rCBV in any territory (P > .05). In the non-PCA territories, rMTT decreased and rCBF increased at 1 week after CAS (P < .01), but there was no significant difference between 1-week and 1-year effects (P > .05). For MR spectroscopy, no significant differences were found between 1 week after CAS and pretreatment (P > .05); the 1-year scores improved significantly (P < .01).

CONCLUSIONS

The long-term hemodynamic and clinical results after treatment validated that CAS is a durable procedure. The 1-week hemodynamic effects can predict long-term effects.

Prediction of cerebral hyperperfusion after carotid endarterectomy with transcranial Doppler

OBJECTIVES

To determine the diagnostic value for predicting cerebral hyperperfusion syndrome (CHS) by adding a transcranial Doppler (TCD) measurement in the early postoperative phase after carotid endarterectomy (CEA).

DESIGN

Patients who underwent carotid endarterectomy between January 2004 and August 2010 and in whom both intra- and postoperative TCD monitoring were performed were included.

METHODS

In 184 CEA patients the mean velocity (V(mean)) preoperatively (V1), pre-clamping (V2), post-declamping (V3) and postoperatively (V4) was measured using TCD. The intra-operative V(mean) increase ((V3 - V2)/V2) was compared to the postoperative increase ((V4 - V1)/V1) in relation to CHS. CHS was diagnosed if the patient developed neurological complaints in the presence of a preoperative V(mean) increase >100%.

RESULTS

Sixteen patients (9%) had an intra-operative V(mean) increase >100% and 22 patients (12%) a postoperative V(mean) increase of >100%. In 10 patients (5%) CHS was diagnosed; two of those had an intra-operative V(mean) increase of >100% and nine postoperative V(mean) increase >100%. This results in a positive predictive value of 13% for the intra-operative and 41% for the postoperative measurement.

CONCLUSIONS

Besides the commonly used intra-operative TCD monitoring additional TCD measurement in the early postoperative phase is useful to more accurately predict CHS after CEA.

Intraprocedural prediction of hemorrhagic cerebral hyperperfusion syndrome after carotid artery stenting

Hyperperfusion syndrome (HPS) is a rare but severe complication after carotid artery stenting (CAS). Reliable methods for predicting HPS remain to be developed. We aimed to establish a predictive value of hemorrhagic HPS after CAS. Our retrospective study included 136 consecutive patients who had undergone CAS. We determined the cerebral circulation time (CCT) by measuring the interval between the point of maximal opacification of the terminal portion of the internal carotid artery and the cortical vein. We calculated intraprocedural CCT changes (ΔCCT) by subtracting postprocedural CCT values from preprocedural CCT values. The mean ΔCCT was 0.9 ± 0.9 seconds; 3 patients (2.2%) with prolonged ΔCCT (2.7, 5.4, and 5.8 seconds) developed HPS. The cutoff time of 2.7 seconds predicted hemorrhagic HPS retrospectively with 100% sensitivity and 99% specificity. Our findings suggest that post-CAS HPS can be predicted by using the ΔCCT value obtained by intraprocedural digital subtraction angiography. Patients with a ΔCCT >2.7 seconds require careful intensive hemodynamic and neurologic monitoring after CAS.

A computational model study of the influence of the anatomy of the circle of willis on cerebral hyperperfusion following carotid artery surgery

BACKGROUND

Cerebral hyperperfusion syndrome develops in a small subset of patients following carotid artery surgery (CAS) performed to treat severe carotid artery stenosis. This syndrome has been found to have a close correlation with cerebral hyperperfusion occurring after CAS. The purpose of this study is to investigate whether and how the anatomy of the Circle of Willis (CoW) of the cerebral circulation influences post-CAS cerebral hyperperfusion.

METHODS

A computational model of the cerebral circulation coupled with the global cardiovascular system has been developed to investigate hemodynamic events associated with CAS. Nine topological structures of the CoW were investigated in combination with various distribution patterns of stenosis in the feeding arteries of the cerebral circulation.

RESULTS

The occurrence of post-CAS cerebral hyperperfusion was predicted for the CoW structures that have poor collateral pathways between the stenosed cerebral feeding arteries and the remaining normal feeding arteries. The risk and the localization of post-CAS hyperperfusion were determined jointly by the anatomy of the CoW and the distribution pattern of stenosis in the cerebral feeding arteries. The presence of basilar artery stenosis or contralateral ICA stenosis increased the risk of post-CAS hyperperfusion and enlarged the cerebral region affected by hyperperfusion. For a certain CoW structure, the diameters of the cerebral communicating arteries and the severity of carotid artery stenosis both had a significant influence on the computed post-CAS cerebral hyperperfusion rates. Moreover, post-CAS cerebral hyperperfusion was predicted to be accompanied with an excessively high capillary transmural pressure.

CONCLUSIONS

This study demonstrated the importance of considering the anatomy of the CoW in assessing the risk of post-CAS cerebral hyperperfusion. Particularly, since the anatomy of the CoW and the distribution pattern of stenosis in the cerebral feeding arteries jointly determine the risk and localization of post-CAS cerebral hyperperfusion, a patient-specific hemodynamic analysis aimed to help physicians identify patients at high risk of cerebral hyperperfusion should account for the combined effect of the anatomy of cerebral arteries and cerebral feeding artery stenoses on cerebral hemodynamics.

Treatment of seizures in the neurologic intensive care unit

Seizures occur more often in the neurologic intensive care unit (NICU) than in general or other specialty ICUs, in part because of the patient population, but also due to the enhanced neurologic monitoring undertaken in such units. Especially important for the detection of seizures is the use of specialty trained personnel and the use of continuous electroencephalographic monitoring. The etiology of seizures often can be categorized either by primary brain pathology, at macro- or microscopic level, or by physiologic derangements of critical care illness, such as toxic or metabolic abnormalities. Particular etiologies at risk for seizures include hemorrhagic stroke and traumatic brain injury. The use of prophylactic antiepileptic drug administration remains controversial. If seizures occur, patients are typically treated with parenteral antiepileptic drugs. The duration of treatment is unclear in most situations, but data support limited treatment for early-onset ICU seizures that are easily controlled, with treatment not extending beyond a few weeks or a month. Late seizures, which occur more than 2 weeks after the insult, have a more ominous correlative risk for subsequent epilepsy and should be treated for extended periods of time or indefinitely. Electrolyte and glucose abnormalities, when corrected, usually lead to seizure control. This review concludes by examining the treatment algorithms for simple seizures and status epilepticus and the role newer antiepileptic use can play in the NICU.

Isolated Subarachnoidal Hemorrhage following Carotid Endarterectomy

Cerebral hyperperfusion syndrome is a rare but well-described complication following carotid endarterectomy or stenting. Clinical signs are ipsilateral, throbbing, unilateral headache with nausea or vomiting, seizures, and neurological deficits, with or without intracerebral abnormalities on CT scan, such as brain edema or intracerebral hemorrhage. Subarachnoidal hemorrhage is rarely described especially if it occurs isolated. We describe a 74-year-old man with a history of high blood pressure, hypercholesterolemia, atrioventricular block with pacemaker, and ischemic cardiopathy with coronary bypass. He underwent right carotid endarterectomy for a 90% NASCET asymptomatic stenosis. Four days after surgery, he complained of unusual headaches with right, throbbing hemicrania. Nine days after surgery, he presented with left hemiplegia and a partial motor seizure. He had fluctuant altered consciousness, left hemiplegia, and left visual and sensory neglect. Brain CT showed right frontal subarachnoidal hemorrhage without parenchymal bleeding. Cerebral angiography found no cerebral aneurysm, no vascular malformation, but a vasospasm of the left middle cerebral artery. Transcranial Doppler confirmed this vasospasm. Evolution was favorable with no recurrence of seizures but with an improvement of the neurological deficits and vasospasm. Physicians should bear in mind this very rare complication of endarterectomy and immediately perform neuroimaging in case of unusual headache following endarterectomy or angioplasty.

POSTCAROTID ENDARTERECTOMY CEREBRAL HYPERPERFUSION CAN BE PREVENTED BY MINIMIZING INTRAOPERATIVE CEREBRAL ISCHEMIA AND STRICT POSTOPERATIVE BLOOD PRESSURE CONTROL UNDER CONTINUOUS SEDATION

OBJECTIVE

Cerebral hyperperfusion syndrome is a major complication after carotid endarterectomy (CEA). We investigated whether our strategy of minimizing intraoperative cerebral ischemia and strict postoperative blood pressure control under continuous sedation prevented postoperative hyperperfusion.

METHODS

Eighty consecutive patients undergoing CEA were studied. A shunt was used in all patients during CEA. All patients were managed postoperatively under continuous sedation for as long as 48 hours on the basis of the regional cerebral blood flow (rCBF) measured immediately after CEA. Postoperative hyperperfusion was assessed, on the basis of the cerebral blood flow study under sedation (propofol) after CEA, either as a greater than 30% increase in rCBF compared with the contralateral side, or a greater than 100% increase in the corrected rCBF (calculated from percentage reduction of the contralateral rCBF induced by propofol) compared with preoperative values.

RESULTS

No patient developed cerebral hyperperfusion syndrome. Postoperative hyperperfusion was found at very low rates (2.5% in the middle cerebral artery territory and 1.3% in the anterior cerebral artery territory by definition 1, and 0% in both territories by definition 2). Ratios of regional oxygen saturation after internal carotid artery clamping to preclamp baseline values were greater than 0.9 in 78 of 80 patients, indicating very mild intraoperative cerebral ischemia. Parameters related to cerebral ischemia during CEA, such as regional oxygen saturation, internal carotid artery cross-clamping duration, and stump pressure (index), did not affect the incidence of postoperative hyperperfusion.

CONCLUSION

The present study suggests that minimizing intraoperative cerebral ischemia using a shunt, followed by strict postoperative blood pressure control under continuous sedation, can prevent post-CEA hyperperfusion.

Transcranial Doppler ultrasonography: a diagnostic tool of increasing utility

PURPOSE OF REVIEW

Since its introduction in 1982, transcranial Doppler ultrasonography has become an important diagnostic and monitoring tool in patients with surgical disease. It has applications in the perioperative period, as well as in the intensive care unit. It is therefore appropriate for the anesthesiologist to maintain an understanding of its current utility.

RECENT FINDINGS

Transcranial Doppler has an established role in diagnosing cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage and for guiding transfusion therapy in children with sickle cell disease. It has application in the preoperative evaluation of patients with cerebrovascular disease, as well as that of an intraoperative monitor in carotid endarterectomy and carotid stenting. It is useful for detecting right-to-left shunts in settings in which transesophageal echocardiography is not desirable. Its value in settings such as traumatic brain injury, hepatic failure, and migraine headache has yet to be fully clarified.

SUMMARY

Although there are several settings in which transcranial Doppler has well established usefulness, there are many more in which it is likely valuable, such as traumatic brain injury, ischemic stroke, and fulminant hepatic failure. Further research is needed in these fields to elucidate the exact role for transcranial Doppler.

Intracranial hemorrhage associated with cerebral hyperperfusion syndrome following carotid endarterectomy and carotid artery stenting: retrospective review of 4494 patients

Object

Intracranial hemorrhage associated with cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) or carotid artery stenting (CAS) is a rare but potentially devastating complication. In the present study the authors evaluated 4494 patients with carotid artery stenosis who had undergone CEA or CAS to clarify the clinicopathological features and outcomes of those with CHS and associated intracranial hemorrhage.

Methods

Patients with postoperative CHS were retrospectively selected, and clinicopathological features and outcomes were studied.

Results

Sixty-one patients with CHS (1.4%) were identified, and intracranial hemorrhage developed in 27 of them (0.6%). The onset of CHS peaked on the 6th postoperative day in those who had undergone CEA and within 12 hours in those who had undergone CAS. Results of logistic regression analysis demonstrated that poor postoperative control of blood pressure was significantly associated with the development of intracranial hemorrhage in patients with CHS after CEA (p = 0.0164). Note, however, that none of the tested variables were significantly associated with the development of intracranial hemorrhage in patients with CHS after CAS. Mortality (p = 0.0010) and morbidity (p = 0.0172) rates were significantly higher in patients with intracranial hemorrhage than in those without.

Conclusions

Cerebral hyperperfusion syndrome after CEA and CAS occurs with delayed classic and acute presentations, respectively. Although strict control of postoperative blood pressure prevents intracranial hemorrhage in patients with CHS after CEA, there appears to be no relationship between blood pressure control and intracranial hemorrhage in those with CHS after CAS. Finally, the prognosis of CHS in patients with associated intracerebral hemorrhage is poor.

Intensive treatment of hypertension decreases the risk of hyperperfusion and intracerebral hemorrhage following carotid artery stenting

OBJECTIVES

To assess the efficacy of a comprehensive blood pressure (BP) management protocol in reducing intracerebral hemorrhage (ICH) following carotid artery stenting (CAS).

BACKGROUND

Following CAS hyperperfusion syndrome (HPS) can lead to significant morbidity and mortality. Hypertension plays an essential role in its development.

METHODS

We instituted a comprehensive BP protocol following the last case of ICH complicating a CAS procedure. All patients received comprehensive monitoring of BP and treatment to a BP < 140/90 mm Hg; those with a treated stenosis >or=90%, contralateral stenosis >or=80%, and hypertension (i.e., risk factors for HPS) were treated to a BP < 120/80 mm Hg. Patients who developed HPS received parenteral beta-blockers or nitrates titrated to resolution of symptoms and discharged when asymptomatic and normotensive. Patients and families were instructed to measure BP twice daily for 2 weeks and to call if hypertension or headache developed.

RESULTS

A total of 836 patients had CAS, 266 prior to the comprehensive BP management program and 570 subsequently. The incidence of HPS/ICH was 5/266 (1.9%) patients prior to comprehensive BP management and 3/570 (0.5%) patients afterwards, P = 0.12. The incidence of ICH was 3/266 (1.1%) and 0/570, respectively, P = 0.032. In high-risk patients both HPS and ICH were significantly reduced from 29.4 to 4.2% (P = 0.006) and 17.6-0% (P = 0.006), respectively. There were no complications attributable to the comprehensive program and lengths of hospitalization were similar (2.6 vs. 2.1 days, P = 0.18).

CONCLUSIONS

Comprehensive management of arterial hypertension can lower the incidence of ICH and HPS in high-risk patients following CAS, without additional complications or prolonged hospitalizations.

Carotid endarterectomy

Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation. There is now substantial evidence to support early operation in symptomatic patients, ideally within 2 weeks of the last neurological symptoms. Thus, the anaesthetist may be faced with a high risk patient in whom there has been limited time for preoperative preparation. The operation may be performed under local or general anaesthesia. The advantages and disadvantages of both are explored in this review. Carotid shunting may offer a degree of cerebral protection, but carries its own risks and has not been proved to reduce morbidity and mortality. The use of carotid shunts is based on clinical judgement, awake neurological monitoring, and the use of monitors of cerebral perfusion. There is no ideal monitor of cerebral perfusion in the patient receiving general anaesthesia. Both the intraoperative and postoperative periods may be witness to dramatic haemodynamic changes that may compromise the cerebral or myocardial circulations. In particular, postoperative hypotension may compromise both myocardial and cerebral perfusion, and severe hypertension can cause cerebral hyperperfusion. There is as yet limited evidence to guide the management of these problems. In summary, CEA can yield significant benefit, but those with the most to gain from the operation also present the greatest challenge to the anaesthetist.

Effects of clonidine and superficial cervical plexus block on hemodynamic stability after carotid endarterectomy

OBJECTIVES

To evaluate the effects of 2 interventions (intravenous clonidine and superficial cervical block) on hemodynamic stability after carotid endarterectomy and to identify variables associated with hemodynamic instability.

DESIGN

Prospective, observational study, sequential enrollment.

SETTING

University hospital.

PARTICIPANTS

Two hundred seventy-five patients undergoing elective carotid endarterectomy under general anesthesia.

INTERVENTIONS

Group NN (n = 50) received no intervention. In group CN (n = 85), 3 mug/kg of clonidine were administered intravenously 30 minutes before the end of the operation. Group CB (n = 140) additionally received a superficial cervical plexus block (SCB) with 20 mL of naropine 0.5% before the induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Clonidine alone (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.45-3.76) and clonidine combined with an SCB (OR, 4.99; 95% CI, 3.19-7.82) resulted in a significant increase in hemodynamic stability after CEA (p < 0.001) from 53.3% (NN) to 70.0% (CN) and 83.3% (CB), respectively. The need for rescue medication decreased from 40.0% to 17.6% and 13.6% (p < 0.001). Both interventions significantly reduced the need for postoperative opioid analgesics (p < 0.01). Logistic regression analysis showed preoperative systolic blood pressure values greater than 170 mmHg (OR, 3.23; 95% CI, 1.76-5.93), previous cardiac interventions (OR, 3.3; 95% CI, 1.54-7.11), and the need for rescue medication in the awakening period (OR, 5.8; 95% CI, 2.88-11.52) to be independent risk factors for postoperative hemodynamic instability (p < or = 0.002).

CONCLUSIONS

Intravenous clonidine and superficial cervical block significantly improve cardiovascular stability after carotid endarterectomy. Patients with pre-existing excessive hypertension and previous coronary interventions must be considered a high-risk group.

Intracranial Hemorrhage After Carotid Angioplasty:A Pooled Analysis

PURPOSE

To use a pooled analysis of the literature to find the incidence of and characteristics common to intracranial hemorrhage (ICH) associated with carotid artery stenting (CAS).

METHODS

A search of the English-language literature (1996-2005) was performed in PubMed to find cases of CAS-associated ICH. Information was derived from the identified case studies in 5 categories and 19 aspects: (1) incidence of CAS-associated ICH; (2) demographic data (sex, age, symptom presentation, and presence of preexisting hypertension); (3) imaging data (side of lesion, degree of maximal stenosis, lesion location, status of the contralateral carotid artery, collateral circulation, and preprocedural imaging features); 4) procedure-related characteristics (antithrombotic medication, use of cerebral protection devices, residual stenosis, symptoms, interval from the procedure to ICH, type of ICH, and blood pressure changes); and (5) clinical outcome.

RESULTS

Fifty-four cases of CAS-associated ICH were reviewed: 51 cases from 36 published articles and our own 3 cases. The incidence of CAS-associated ICH was 0.63% (95% CI 0.38% to 0.97%) in studies consisting of >100 cases, which was significantly lower (p<0.0001) than that of case series consisting of <100 cases (2.69%, 95% CI 1.75% to 3.94%). Distinctive features included symptomatic lesions, severe stenosis (> or =90%), maximal stenosis in the internal carotid artery (ICA) distal to the bifurcation, and preexisting cerebral infarction.

CONCLUSION

The incidence of CAS-associated ICH was significantly lower in series consisting of >100 cases. More caution should be directed toward patients with symptomatic lesions, severe stenosis, maximal ICA stenosis distal to the carotid bifurcation, and preexisting cerebral infarction.

Case report: Aggressive blood pressure management for carotid endarterectomy hyperperfusion syndrome

PURPOSE

Cerebral hyperperfusion syndrome (CHS) is a rare but potentially devastating complication following cerebral revascularization. Management of CHS requires aggressive blood pressure control to prevent stroke and intracerebral hemorrhage. This case report documents a severe case of CHS, and outlines a successful outcome associated with aggressive blood pressure control.

CLINICAL FEATURES

A 67-yr-old gentleman, nine days post left carotid endarterectomy, required tracheal intubation and intensive care unit admission following seizures and acute right-sided weakness. A computed tomography scan and magnetic resonance imaging revealed significant vasogenic edema in the left middle cerebral artery territory, without evidence of infarction. The history and radiographic findings suggested CHS. As such, a systolic blood pressure target was set at 90-140 mmHg. This blood pressure parameter was lower than typically targeted following acute ischemic or hemorrhagic stroke. Rapid clinical improvements were seen by day five, and tight blood pressure control was maintained throughout. Repeat computed tomography and magnetic resonance imaging revealed improved edema and no evidence of infarct or hemorrhage.

CONCLUSION

Cerebral hyperperfusion syndrome is believed to occur following restoration of blood flow to a brain with impaired autoregulation due to chronic hypoperfusion. Massive brain edema and hemorrhage can result from higher pressures. Clinicians should be aware of this potential complication following cerebral revascularization procedures, and the importance of establishing blood pressure targets which are considerably lower than for other patients with similar clinical presentations.

Instability of Doppler cerebral blood flow in monochorionic twins

OBJECTIVE

The purpose of this study was to evaluate Doppler flow velocity changes in cerebral vessels of monochorionic twins with twin-twin transfusion syndrome (TTTS).

METHODS

Repeated Doppler umbilical and cerebral blood flow studies were performed in 7 twin pairs with TTTS. Eight monochorionic twin pairs and 11 dichorionic twin pairs served as control groups. The following Doppler parameters were assessed: umbilical artery pulsatility index (PI), middle cerebral artery (MCA) PI, cerebroplacental ratio, delta PI between the umbilical artery and MCA, and peak systolic velocity (PSV) in the MCA.

RESULTS

Significant variations in PSV in the MCA and cerebral indices were found in the study group of monochorionic twins with TTTS. Periods of high PSV with low PI in the MCA were followed by lower PSV in the same fetus. Repeated measurements in the comparison groups were stable without significant variations. The delta cerebroplacental ratio was significantly higher in the study group (0.38 versus 0.09 and 0.19 in the comparison groups; P < .02).

CONCLUSIONS

Significant changes in Doppler flow velocity and indices suggest instability of cerebral blood flow with episodes of "hyperperfusion" in monochorionic twins with TTTS. Further studies are needed to elucidate the relationship of these transient changes to neurologic sequelae in the neonate.

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.

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.