Intraprocedural prediction of hemorrhagic cerebral hyperperfusion syndrome after carotid artery stenting

Flat Detector CT with Cerebral Pooled Blood Volume Perfusion in the Angiography Suite: From Diagnostics to Treatment Monitoring

C-arm flat-panel detector computed tomographic (CT) imaging in the angiography suite increasingly plays an important part during interventional neuroradiological procedures. In addition to conventional angiographic imaging of blood vessels, flat detector CT (FD CT) imaging allows simultaneous 3D visualization of parenchymal and vascular structures of the brain. Next to imaging of anatomical structures, it is also possible to perform FD CT perfusion imaging of the brain by means of cerebral blood volume (CBV) or pooled blood volume (PBV) mapping during steady state contrast administration. This enables more adequate decision making during interventional neuroradiological procedures, based on real-time insights into brain perfusion on the spot, obviating time consuming and often difficult transportation of the (anesthetized) patient to conventional cross-sectional imaging modalities. In this paper we review the literature about the nature of FD CT PBV mapping in patients and demonstrate its current use for diagnosis and treatment monitoring in interventional neuroradiology.

Clinical Predictors of Hyperperfusion Syndrome Following Carotid Stenting: Results From a National Prospective Multicenter Study

OBJECTIVES

The aim of the HISPANIAS (HyperperfusIon Syndrome Post-carotid ANgIoplasty And Stenting) study was to define CHS rates and develop a clinical predictive model for cerebral hyperperfusion syndrome (CHS) after carotid artery stenting (CAS).

BACKGROUND

CHS is a severe complication following CAS. The presence of clinical manifestations is estimated on the basis of retrospective reviews and is still uncertain.

METHODS

The HISPANIAS study was a national prospective multicenter study with 14 recruiting hospitals. CHS was classified as mild (headache only) and moderate-severe (seizure, impaired level of consciousness, or development of focal neurological signs).

RESULTS

A total of 757 CAS procedures were performed. CHS occurred in 22 (2.9%) patients, in which 16 (2.1%) had moderate-severe CHS and 6 (0.8%) had mild CHS (only headache). The rate of hemorrhages was 0.7% and was associated with high mortality (20%). Pre-operative predictors of moderate-severe CHS in multivariate analysis were female sex (odds ratio [OR]: 3.24; 95% confidence interval [CI]: 1.11 to 9.47; p = 0.03), older patients (OR: 1.09; 95% CI: 1.01 to 1.17; p = 0.02), left carotid artery treated (OR: 4.13; 95% CI: 1.11 to 15.40; p = 0.03), and chronic renal failure (OR: 6.29; 95% CI: 1.75 to 22.57; p = 0.005). The area under the curve of this clinical and radiological model was 0.86 (95% CI: 0.81 to 0.92; p = 0.001).

CONCLUSIONS

The rate of CHS in the HISPANIAS study was 2.9%, with moderate-severe CHS of 2.1%. CHS was independently associated with female sex, older age, history of chronic kidney disease, and a treated left carotid artery. Although further investigations are needed, the authors propose a model to identify high-risk patients and develop strategies to decrease CHS morbidity and mortality in the future.

Update on cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) is a clinical syndrome following a revascularization procedure. In the past decade, neurointerventional surgery has become a standard procedure to treat stenotic or occluded cerebral vessels in both acute and chronic settings, as well as endovascular thrombectomy in acute ischemic stroke. This review aims to summarize relevant recent studies regarding the epidemiology, diagnosis, and management of CHS as well as to highlight areas of uncertainty. Extracranial and intracranial cerebrovascular diseases in acute and chronic conditions are considered. The definition and diagnostic criteria of CHS are diverse. Although impaired cerebrovascular autoregulation plays a major role in the pathophysiology of CHS, the underlying mechanism is still not fully understood. Its clinical characteristics vary in different patients. The current findings on clinical and radiological presentation, pathophysiology, incidence, and risk factors are based predominantly on carotid angioplasty and stenting studies. Hemodynamic assessment using imaging modalities is the main form of diagnosis although the criteria are distinct, but it is helpful for patient selection before an elective revascularization procedure is conducted. After endovascular thrombectomy, a diagnosis of CHS is even more complex, and physicians should consider concomitant reperfusion injury. Management and preventative measures, including intensive blood pressure control before, during, and after revascularization procedures and staged angioplasty, are discussed in detail.

Factors influencing blood flow resistance from a large internal carotid artery aneurysm revealed by a computational fluid dynamics model

Hyperperfusion syndrome occurs after treatment of a large or giant cerebral aneurysm. Recently, flow-diverter stent placement has emerged as an effective treatment method for a large cerebral aneurysm, but postoperative ipsilateral delayed intraparenchymal hemorrhage occurs in a minority of cases. The mechanism underlying delayed intraparenchymal hemorrhage is not established, but one possibility is hyperperfusion syndrome. The incidence of delayed intraparenchymal hemorrhage appears to be higher for giant aneurysms; hence, we speculated that large/giant aneurysms may create flow resistance, and mitigation by flow-diverter stent deployment leads to hyperperfusion syndrome and delayed intraparenchymal hemorrhage. The purpose of this study was to identify aneurysm characteristics promoting flow resistance by the analysis of pressure loss in an internal carotid artery paraclinoid aneurysm model using computational fluid dynamics. A virtual U-shaped model of the internal carotid artery siphon portion was created with a spherical aneurysm of various angles, body diameters, and neck diameters. Visualization of streamlines, were calculated of pressure loss between proximal and distal sides of the aneurysm, and vorticity within the aneurysm were calculated. The pressure loss and vorticity demonstrated similar changes according to angle, peaking at 60°. In contrast, aneurysm diameter had little influence on pressure loss. Larger neck width, however, increases pressure loss. Our model predicts that aneurysm location and neck diameter can increase the flow resistance from a large internal carotid artery aneurysm. Patients with large aneurysm angles and neck diameters may be at increased risk of hyperperfusion syndrome and ensuing delayed intraparenchymal hemorrhage following flow-diverter stent treatment.

A novel model of cerebral hyperperfusion with blood-brain barrier breakdown, white matter injury, and cognitive dysfunction

OBJECTIVE

Cerebral hyperperfusion (CHP) is associated with considerable morbidity. Its pathophysiology involves disruption of the blood-brain barrier (BBB) with subsequent events such as vasogenic brain edema and ischemic and/or hemorrhagic complications. Researchers are trying to mimic the condition of CHP; however, a proper animal model is still lacking. In this paper the authors report a novel surgically induced CHP model that mimics the reported pathophysiology of clinical CHP including BBB breakdown, white matter (WM) injury, inflammation, and cognitive impairment.

METHODS

Male Sprague-Dawley rats were subjected to unilateral common carotid artery (CCA) occlusion and contralateral CCA stenosis. Three days after the initial surgery, the stenosis of CCA was released to induce CHP. Cortical regional cerebral blood flow was measured using laser speckle flowmetry. BBB breakdown was assessed by Evans blue dye extravasation and matrix metalloproteinase-9 levels. WM injury was investigated with Luxol fast blue staining. Cognitive function was assessed using the Barnes circular maze. Other changes pertaining to inflammation were also assessed. Sham-operated animals were prepared and used as controls.

RESULTS

Cerebral blood flow was significantly raised in the cerebral cortex after CHP induction. CHP induced BBB breakdown evident by Evans blue dye extravasation, and matrix metalloproteinase-9 was identified as a possible culprit. WM degeneration was evident in the corpus callosum and corpus striatum. Immunohistochemistry revealed macrophage activation and glial cell upregulation as an inflammatory response to CHP in the striatum and cerebral cortex. CHP also caused significant impairments in spatial learning and memory compared with the sham-operated animals.

CONCLUSIONS

The authors report a novel CHP model in rats that represents the pathophysiology of CHP observed in various clinical scenarios. This model was produced without the use of pharmacological agents; therefore, it is ideal to study the pathology of CHP as well as to perform preclinical drug trials.

Clinical Impact of Intracerebral Hemorrhage after Hyperacute Extracranial Stenting in Patients with Ischemic Stroke

PURPOSE

Emergent intracranial occlusions causing acute ischemic stroke are often related to extracranial atherosclerotic stenosis. This study aimed to investigate the association between post-procedure intracerebral hemorrhage (ICH) and emergent extracranial artery stenting and assess their effects on clinical outcomes in patients with acute ischemic stroke.

MATERIALS AND METHODS

We retrospectively analyzed patients undergoing hyperacute endovascular treatment for cervicocephalic vascular occlusion in three Korean hospitals between January 2011 and February 2016. Patients who had extracranial artery involvement and were treated from 24 hours of symptom onset to puncture were included in this study, and they were divided into the extracranial stenting (ES) and non-ES groups. Any type of petechial hemorrhages and parenchymal hematoma was defined as ICH for the current study.

RESULTS

In total, 76 patients were included in this study. Among them, 56 patients underwent ES, and 20 patients did not. Baseline characteristics, risk factors, laboratory data, treatment methods, successful reperfusion rates, and baseline stenotic degrees of extracranial internal carotid artery did not differ between these two groups. However, atrial fibrillation was more frequent in patients without than with ES (P=0.002), and post-procedure ICH was more frequent in patients with than without ES (P=0.035). Logistic regression models revealed that ES was independently associated with post-procedure ICH (odds ratio [OR], 7.807; 95% confidence interval [CI], 1.213-50.248; P=0.031), and ICH was independently associated with poor clinical outcomes (OR, 0.202; 95% CI, 0.054-0.759; P=0.018); however, ES itself was not associated with clinical outcomes (OR, 0.530; 95% CI, 0.117-2.395; P=0.409). Notably, ICH and ES had interaction for predicting good outcomes (P=0.041).

CONCLUSION

Post-procedure ICH was associated with ES and poor clinical outcomes. Therefore, ES should be cautiously considered in patients with hyperacute stroke.

Fluoroscopic angiography quantifies delay in cerebral circulation time and requires less radiation in carotid stenosis patients: A pilot study

BACKGROUND

Quantitative digital subtraction angiography (DSA) facilitates in-room assessment of flow changes in various cerebrovascular diseases and improves patient safety. The purpose of this study was to compare the diagnostic accuracy of quantitative fluoroscopic angiography (FA) and DSA.

METHODS

Twenty-two patients with >70% carotid stenosis according to NASCET criteria were prospectively included in the study. All patients received DSA and FA (ArtisZee, Siemens Healthcare, Forchheim, Germany) before and after carotid stenting in the same angiosuite. The regions of interest (ROIs) included the extracranial internal carotid artery (eICA), first segment of the middle cerebral artery (MCA1), and sigmoid sinus in the anterior-posterior view; cavernous portion of the ICA (cICA), parietal vein, and jugular vein in the lateral views. The time-to-peak (TTP) for all ROIs and cerebral circulation time (CCT) were measured from FA and DSA scans. TTP, CCT, and radiation doses from DSA were compared with those from FA.

RESULTS

The mean age of the patients were 69 ± 9.5 years old. The average stenosis was 89.7% ± 7.8% before stenting and 31% ± 3.6% after stenting. No patient suffered from periprocedural stroke. The intermethod correlation for TTP for all ROIs except the eICA and cICA ranged from 0.46 to 0.65 before stenting and 0.57 to 0.73 after stenting, and that for CCT was 0.65 before stenting and 0.57 after stenting. The radiation doses were significantly lower for FA than for DSA regardless of views or periprocedural timing (p < 0.001).

CONCLUSION

Stenosis facilitated the creation of a bolus by manual injection and therefore increased the accuracy of cerebral flow quantification in FA. Cerebral hemodynamic assessment by FA is quicker and associated with less radiation.

Risk factors for hyperperfusion-induced intracranial hemorrhage after carotid artery stenting in patients with symptomatic severe carotid stenosis evaluation

Background

Analyzing risk factors for hyperperfusion-induced intracranial hemorrhage (HICH) after carotid artery stenting (CAS) in patients with symptomatic severe carotid stenosis.

Methods

This study retrospectively analyzed clinical data of 210 patients, who had symptomatic severe carotid stenosis (70–99%) and received CAS treatment between June 2009 and June 2015, and evaluated the relationship of HICH with patients’ clinical baseline data, imaging features, and treatment strategies.

Results

Seven patients (3.3%) developed HICH after CAS. The incidence of HICH among patients with near total occlusion was significantly higher than among those without (10.1% vs 0%, P<0.001). Out of the seven, five had no development of either anterior or posterior circulations, and two had no development of anterior circulation and poor development of posterior circulation. Results showed that patients with poor compensation of Willis’ Circle were more likely to develop HICH compared with other patients (P<0.001). All patients received preoperative CT perfusion. TTP index was defined as the TTP ratio between the affected and contralateral side. The results showed that the TTP index was significantly different between the HICH group and non-HICH group (1.15±0.10 vs 1.30±0.15, P<0.001). An analysis of the ROC curve indicated that patients with TTP index >1.22 were more likely to develop HICH compared with other patients (sensitivity 100%, specificity 75.9%).

Conclusions

Patients with severe unilateral carotid stenosis, the presence of near total occlusion, poor compensation of Willis’ Circle, and preoperative TTP index>1.22, have a higher risk of developing HICH after CAS.

Change in Cerebral Blood Flow after Palliative Percutaneous Angioplasty and Timing of Second Stage Carotid Artery Stenting in Staged Angioplasty

The purpose of this study is to elucidate the hemodynamic changes after palliative angioplasty and the timing of second stage carotid artery stenting (CAS) in staged angioplasty for patients with severe hemodynamically compromised carotid artery stenosis. Among consecutive 111 patients with carotid artery stenosis, chronological changes in the cerebral blood flow of all 11 hemodynamically compromised patients treated with CAS were evaluated with single photon emission computed tomogram (SPECT) in each stage of the treatment. Ten of these 11 patients underwent staged angioplasty and one was treated with single-stage CAS. All the 10 patients who underwent staged angioplasty showed improved cerebral vascular reactivity (CVR) on SPECT after the first stage palliative angioplasty. Only one patient treated with staged angioplasty with 4-week interval before the CAS showed restenosis of the lesion. Cerebral hyperperfusion syndrome (CHS) was not observed in nine of 10 patients with staged angioplasty. One patient of staged angioplasty (who presented restenosis at the time of elective CAS) and another patient in whom we could not apply staged angioplasty (for his renal dysfunction) showed CHS after CAS. In conclusion, restoration of CVR could be achieved within a few days following palliative angioplasty, and 1–2-week interval is enough for staged angioplasty.

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.

Automatic flow analysis of digital subtraction angiography using independent component analysis in patients with carotid stenosis

PURPOSE

Current time-density curve analysis of digital subtraction angiography (DSA) provides intravascular flow information but requires manual vasculature selection. We developed an angiographic marker that represents cerebral perfusion by using automatic independent component analysis.

MATERIALS AND METHODS

We retrospectively analyzed the data of 44 patients with unilateral carotid stenosis higher than 70% according to North American Symptomatic Carotid Endarterectomy Trial criteria. For all patients, magnetic resonance perfusion (MRP) was performed one day before DSA. Fixed contrast injection protocols and DSA acquisition parameters were used before stenting. The cerebral circulation time (CCT) was defined as the difference in the time to peak between the parietal vein and cavernous internal carotid artery in a lateral angiogram. Both anterior-posterior and lateral DSA views were processed using independent component analysis, and the capillary angiogram was extracted automatically. The full width at half maximum of the time-density curve in the capillary phase in the anterior-posterior and lateral DSA views was defined as the angiographic mean transient time (aMTT; i.e., aMTTAP and aMTTLat). The correlations between the degree of stenosis, CCT, aMTTAP and aMTTLat, and MRP parameters were evaluated.

RESULTS

The degree of stenosis showed no correlation with CCT, aMTTAP, aMTTLat, or any MRP parameter. CCT showed a strong correlation with aMTTAP (r = 0.67) and aMTTLat (r = 0.72). Among the MRP parameters, CCT showed only a moderate correlation with MTT (r = 0.67) and Tmax (r = 0.40). aMTTAP showed a moderate correlation with Tmax (r = 0.42) and a strong correlation with MTT (r = 0.77). aMTTLat also showed similar correlations with Tmax (r = 0.59) and MTT (r = 0.73).

CONCLUSION

Apart from vascular anatomy, aMTT estimates brain parenchyma hemodynamics from DSA and is concordant with MRP. This process is completely automatic and provides immediate measurement of quantitative peritherapeutic brain parenchyma changes during stenting.

Changes in contrast transit times on digital subtraction angiography post-Pipeline Embolization Device deployment

It is postulated that hemodynamic changes occur in the distal vascular bed post-deployment of Pipeline Embolization Devices (PEDs). In this paper, we evaluate changes in the contrast transit times (TTs) on digital subtraction angiography (DSA) post-PED interventions. DSA films were analyzed using custom-made software for the time-density relationship at baseline and compared to post-PED deployment. All analyses were performed within the middle cerebral artery (MCA) M1 segment. Analyses included TT10%-100% (time needed for the contrast to change from 10% image intensity to 100%), TT100%-10%, and TT25%-25%. Forty-four patients were included. We found a significant decrease in TT10%-100% (2.79 to 2.24 seconds, p < 0.001) post-PED. There was a significant correlation between the percentage change in TT100%-10% and aneurysm size ( p = 0.02). There was also a significant decrease in TT25%-25% (7.07 to 6.41 seconds, p = 0.02) post-PED. Moreover, there was a significant correlation between the absolute or percentage changes in TT25%-25% and aneurysm size (rho = 0.54, p = 0.05 and rho = 0.29, p = 0.05, respectively). Statistically significant distal intracranial hemodynamic changes occur post-PED deployment. These hemodynamic changes appear to be more pronounced with large and giant aneurysms.

Clinical Comparison of Outcomes of Early versus Delayed Carotid Artery Stenting for Symptomatic Cerebral Watershed Infarction due to Stenosis of the Proximal Internal Carotid Artery

The aim of this study was to compare the clinical outcomes of early versus delayed carotid artery stenting (CAS) for symptomatic cerebral watershed infarction (sCWI) patients due to stenosis of the proximal internal carotid artery. We retrospectively collected clinical data of those who underwent early or delayed CAS from March 2011 to April 2014. The time of early CAS and delayed CAS was within a week of symptom onset and after four weeks from symptom onset. Clinical data such as second stroke, the National Institutes of Health Stroke Scale (NHISS) score, and modified Rankin Scale (mRS) score and periprocedural complications were collected. The rate of second stroke in early CAS group is lower when compared to that of delayed CAS group. There was no significant difference regarding periprocedural complications in both groups. There was a significant difference regarding mean NHISS score 90 days after CAS in two groups. Early CAS group had a significant better good outcome (mRS score ≤ 2) than delayed CAS group. We suggest early CAS for sCWI due to severe proximal internal carotid artery stenosis as it provides lower rate of second stroke, comparable periprocedural complications, and better functional outcomes compared to that of delayed CAS.

Finding the optimal deconvolution algorithm for MR perfusion in carotid stenosis: Correlations with angiographic cerebral circulation time

PURPOSE

The aim of our study is to explore the impacts of different deconvolution algorithms on correlations between CBF, MTT, CBV, TTP, Tmax from MR perfusion (MRP) and angiography cerebral circulation time (CCT).

METHODS

Retrospectively, 30 patients with unilateral carotid stenosis, and available pre-stenting MRP and angiography were included for analysis. All MRPs were conducted in a 1.5-T MR scanner. Standard singular value decomposition, block-circulant, and two delay-corrected algorithms were used as the deconvolution methods. All angiographies were obtained in the same bi-plane flat-detector angiographic machine. A contrast bolus of 12mL was administrated via angiocatheter at a rate of 8mL/s. The acquisition protocols were the same for all cases. CCT was defined as the difference between time to peak from the cavernous ICA and the parietal vein in lateral view. Pearson correlations were calculated for CCT and CBF, MTT, CBV, TTP, Tmax.

RESULTS

The correlation between CCT and MTT was highest with Tmax (r=0.65), followed by MTT (r=0.60), CBF (r=-0.57), and TTP (r=0.33) when standard singular value decomposition was used. No correlation with CBV was noted.

CONCLUSIONS

MRP using a singular value decomposition algorithm confirmed the feasibility of quantifying cerebral blood flow deficit in steno-occlusive disease within the angio-room. This approach might further improve patient safety by providing immediate cerebral hemodynamics without extraradiation and iodine contrast.

Leptomeningeal collateral vessels are a major risk factor for intracranial hemorrhage after carotid stenting in patients with carotid atherosclerotic plaque

AIM

To evaluate the relationship between leptomeningeal collaterals and intracranial hemorrhage (ICH) after carotid artery stenting (CAS).

METHODS

A retrospective study was undertaken of 228 patients (median age 75 years (range 44-90); 187 men and 41 women) who underwent CAS due to unilateral carotid atherosclerotic plaque from January 2009 to December 2013. Cerebral angiographic findings were classified into three patterns: type I, normal visualization of the anterior and middle cerebral arteries without leptomeningeal collaterals; type II, visualization of the middle cerebral artery only without leptomeningeal collaterals; and type III, visualization of leptomeningeal collateral flow.

RESULTS

For all cerebral angiographic findings, 146 (64.0%) were type I, 61 (26.8%) were type II, and 21 (9.2%) were type III. Four patients (1.8%) died with fatal ICH after CAS and had type III angiographic findings (19%). The prevalence of ICH in patients with leptomeningeal collateral vessels was significantly higher than in patients without leptomeningeal collateral vessels (19% vs 0%, p<0.0001). The percentage of carotid stenosis in patients with ICH based on North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria was significantly higher than in patients without ICH (89.8±3.6% vs 72.8±12.8%, p=0.014).

CONCLUSIONS

Leptomeningeal collateral vessels are a major risk factor for ICH after CAS in patients with carotid atherosclerotic plaque.

Changes of time-attenuation curve blood flow parameters in patients with and without carotid stenosis

BACKGROUND AND PURPOSE

From the time-attenuation curves of DSA flow parameters, maximal intensity, maximal slope, and full width at half maximum of selected vascular points are defined. The study explores the reliability of defining the flow parameters by the time-attenuation curves of DSA.

MATERIALS AND METHODS

Seventy patients with unilateral carotid artery stenosis (group A) and 56 healthy controls (group B) were retrospectively enrolled. Fixed contrast injection protocols and DSA acquisition parameters were used with all patients. The M1, sigmoid sinus, and internal jugular vein on anteroposterior view DSA and the M2, parietal vein, and superior sagittal sinus on lateral view DSA were chosen as ROI targets for measuring flow parameters. The difference of time of maximal intensity between 2 target points was defined as the circulation time between the target points.

RESULTS

The maximal intensity difference of 2 selected points from the ICA to the M1, sigmoid sinus, internal jugular vein, M2, parietal vein, and superior sagittal sinus was significantly longer in group A than in group B. The maximum slope of M1, M2, and the superior sagittal sinus was significantly lower in group A than in group B. The full width at half maximum of M1 and M2 was significantly larger in group A than in group B. The maximal slope of M1 demonstrated the best diagnostic performance.

CONCLUSIONS

The maximal intensity difference of 2 selected points derived from DSA can be used as a definitive alternative flow parameter for intracranial circulation time measurement. Maximal slope and full width at half maximum complement the maximal intensity difference of 2 selected points in defining flow characteristics of healthy subjects and patients with carotid stenosis.

Extra-aneurysmal flow modification following pipeline embolization device implantation: focus on regional branches, perforators, and the parent vessel

BACKGROUND AND PURPOSE

Flow-diverter technology has proved to be a safe and effective treatment for intracranial aneurysm based on the concept of flow diversion allowing parent artery and collateral preservation and aneurysm healing. We investigated the patency of covered side branches and flow modification within the parent artery following placement of the Pipeline Embolization Device in the treatment of intracranial aneurysms.

MATERIALS AND METHODS

Sixty-six aneurysms in 59 patients were treated with 96 Pipeline Embolization Devices. We retrospectively reviewed imaging and clinical results during the postoperative period at 6 and 12 months to assess flow modification through the parent artery and side branches. Reperfusion syndrome was assessed by MR imaging and clinical evaluation.

RESULTS

Slow flow was observed in 13 of 68 (19.1%) side branches covered by the Pipeline Embolization Device. It was reported in all cases of anterior cerebral artery coverage, in 3/5 cases of M2-MCA coverage, and in 5/34 (14.7%) cases of ophthalmic artery coverage. One territorial infarction was observed in a case of M2-MCA coverage, without arterial occlusion. One case of deep Sylvian infarct was reported in a case of coverage of MCA perforators. Two ophthalmic arteries (5.9%) were occluded, and 11 side branches (16.2%) were narrowed at 12 months' follow-up; patients remained asymptomatic. Parent vessel flow modification was responsible for 2 cases (3.4%) of reperfusion syndrome. Overall permanent morbidity and mortality rates were 5.2% and 6.9%, respectively. We did not report any permanent deficit or death in case of slow flow observed within side branches.

CONCLUSIONS

After Pipeline Embolization Device placement, reperfusion syndrome was observed in 3.4%, and territorial infarction, in 3.4%. Delayed occlusion of ophthalmic arteries and delayed narrowing of arteries covered by the Pipeline Embolization Device were observed in 5.9% and 16.2%, respectively. No permanent morbidity or death was related to side branch coverage at midterm follow-up.

Neuroanesthesiology update

We review topics pertinent to the perioperative care of patients with neurological disorders. Our review addresses topics not only in the anesthesiology literature, but also in basic neurosciences, critical care medicine, neurology, neurosurgery, radiology, and internal medicine literature. We include literature published or available online up through December 8, 2013. As our review is not able to include all manuscripts, we focus on recurring themes and unique and pivotal investigations. We address the broad topics of general neuroanesthesia, stroke, traumatic brain injury, anesthetic neurotoxicity, neuroprotection, pharmacology, physiology, and nervous system monitoring.

Stenotic transverse sinus predisposes to poststenting hyperperfusion syndrome as evidenced by quantitative analysis of peritherapeutic cerebral circulation time

BACKGROUND AND PURPOSE

Hyperperfusion syndrome is a devastating complication of carotid stent placement. The shortening of cerebral circulation time after stent placement is seen as a good indicator of the development of hyperperfusion syndrome. The purpose of our study was to evaluate whether patients with ipsilateral transverse sinus stenosis are prone to having shortened cerebral circulation time after stent placement, subsequently leading to the possible development of hyperperfusion syndrome.

MATERIALS AND METHODS

Forty-nine patients with >70% unilateral carotid stenosis undergoing stent placement were recruited for analysis. Group A consisted of patients with a stenotic ipsilateral transverse sinus >50% greater than the diameter of the contralateral transverse sinus; the remaining patients were in group B. Quantitative DSA was used to calculate cerebral circulation time. Cerebral circulation time was defined as the time difference between the relative time to maximal intensity of ROIs in the proximal internal carotid artery and the internal jugular vein. ΔCCT was defined as cerebral circulation time before stent placement minus cerebral circulation time after stent placement. ΔCCT, white matter hyperintensity signals, and sulcal effacement in MR imaging were compared between the 2 groups.

RESULTS

ΔCCT was significantly shorter in group A (0.65 ± 1.3) than in group B (-0.12 ± 1.4). Three patients had white matter hyperintensity signals in group A, and 1 developed hyperperfusion syndrome. Group B showed no MR imaging signs of hyperperfusion syndrome.

CONCLUSIONS

Ipsilateral hypoplastic transverse sinus was associated with prolonged cerebral circulation time before stent placement and greatly shortened cerebral circulation time after stent placement. Inadequate venous drainage might play a role in impaired cerebral autoregulation and might influence the development of poststenting hyperperfusion syndrome.

Cerebral hyperperfusion after flow diversion of large intracranial aneurysms

Cerebral hyperperfusion syndrome has been proposed to be caused by rapidly increased blood flow into chronically hypoperfused parenchyma with resultant impaired autoregulation, and has been noted after clipping of intracranial aneurysms and carotid stenting. The occurrence of the syndrome after endovascular flow diversion, however, has not been previously described. A 52-year-old woman was admitted electively for flow diverter treatment of a recurrent ventral paraclinoid aneurysm arising within a dysplastic segment of the left internal carotid artery. During the immediate postprocedural period the patient was found to have confusion, right hemiparesis, facial droop and dysarthria, which resolved with blood pressure control. Subsequent CT perfusion on day 11 demonstrated mildly elevated cerebral blood flow, cerebral blood volume and permeability values in the left hemisphere.