Symptomatic carotid artery occlusion. A reappraisal of hemodynamic factors

Can a closed carotid artery be reopened?

Carotid occlusion is a disease that presents a difficult decision for the treating provider. Traditionally, many providers would opt for expectant management with risk factor reduction and supportive therapy. There is a growing body of literature however pointing to possible improved outcomes of more aggressive treatments, including reopening of the occluded carotid. In this review, we discuss the difficulties involved in diagnosing a patient presenting with symptomatic carotid occlusion, the natural history of the disease, and the emerging treatment options and paradigms of different institutions based on recent literature.

Ipsilateral Infarct in Newly Diagnosed Cervical Internal Carotid Artery Atherosclerotic Occlusion

OBJECTIVE

We aimed to determine factors associated with recent infarct (RI) in patients with newly identified atherosclerotic cervical internal carotid artery occlusion (CICAO).

METHODS

This was a retrospective review of consecutive patients who underwent cervical CT angiography from 2002 to 2006 at a single tertiary center. RI was defined by positive diffusion-weighted imaging/apparent diffusion coefficient magnetic resonance imaging (MRI) in the correspondent CICAO territory. Subjects were dichotomized into those with a RI versus patients with no RI (No-RI).

RESULTS

Of 2,459 patients with cervical CT angiograms in the study period, 108 (4.4%) had complete medical records and brain MRI and were included. The mean age was 64 ± 13 years, 58% were men, and 62 (57%) had a RI. The demographics of the RI and No-RI patients were comparable, with the exception that those with RI had a lower frequency of coronary artery disease (CAD, 13 vs. 54%; p < 0.01) and dyslipidemia (38 vs. 69%; p < 0.01). The use of antiplatelets was not statistically different between the groups (56 vs. 71%; p = 0.1). Subjects with RI were less likely on statins (21 vs. 56%; p < 0.01) and antihypertensives (9 vs. 71%; p < 0.01). Multivariate regression revealed that CAD, the use of statins, and the use of antihypertensives were associated with No-RI CICAO presentation.

CONCLUSION

The use of statins and antihypertensives is associated with a decreased risk of RI atherosclerotic CICAO.

Link between cerebral blood flow and autonomic function in survivors of internal carotid artery occlusion

PURPOSE

Symptomatic internal carotid artery occlusion (ICAO) is an important cause of cerebral ischemia with poor long-term outcome. Reductions in baroreflex function is reported in carotid atherosclerosis and implicated in increased risk of recurrent cardiovascular events. A distributed network of forebrain regions can exert modulatory influences over the cardio-vagal and baroreflex functions. The successful clinical translation of these approaches offers insights into underlying modulatory mechanisms and to possible therapeutic strategy.

METHODS

This study enrolled 20 symptomatic ICAO survivors, 20 patients with small vessel disease (SVD) as risk control, and 20 healthy controls. All underwent a standardized evaluation of cardiovascular autonomic function testing that included baroreflex sensitivity (BRS), Valsalva ratio (VR), and heart rate response to deep breathing (HR_DB). The regional cerebral blood flow (rCBF) of the central autonomic network (CAN) was obtained from arterial spin-labeling magnetic resonance imaging. Parameters of autonomic function between symptomatic ICAO survivors with and those without recurrent cardiovascular events were compared.

RESULTS

Valsalva ratio and HR_DB levels were significantly higher in the control group, followed by the SVD and ICAO groups (p=0.009 and p=0.007, respectively). Spontaneous BRS and BRS during the early phase II of Valsalva maneuver levels were both significantly higher in the control group, followed by the SVD and ICAO groups (p<0.001 and p=0.042, respectively). The rCBF of CAN inversely correlated with spontaneous BRS.

CONCLUSION

Autonomic dysregulation, including reduced BRS and impaired cardio-vagal function in the convalescent stage ICAO, can persist for a long time. Reduced BRS is inversely correlated with CAN activity.

[Stenting vs. surgery for symptomatic carotid stenosis]

Stenting is associated with a higher periprocedural risk of stroke compared to surgery. This higher stroke risk mainly concerns patients older than 70 years, whereas risk seems to be similar in patients younger than 70 years. After the procedural period, both surgery and stenting seem to be as effective to prevent stroke. Surgery remains the first choice intervention in patients with severe symptomatic carotid stenosis. It is reasonable to consider stenting in patients with contraindications to surgery due to technical or anatomical aspects, or in patients at high risk of complications because of comorbidities, after a multidisciplinary discussion. Stenting could also be considered in patients who have low risk of stroke after stenting (e.g., patients younger than 70 years). When a revascularization is indicated, intervention should be done within 2 weeks of the index event after TIA or moderate stroke.

Influence of internal carotid artery stenosis, blood pressure, glycated hemoglobin, and hemoglobin level on fMRI signals of stroke patients

OBJECTIVES

To identify the effect of internal carotid artery (ICA) stenosis, blood pressure (BP), glycated hemoglobin (HbA1c), and hemoglobin level on blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signals in stroke patients.

METHODS

A total of 18 stroke patients with acute cerebral infarction (13 males and 5 females) and 13 age-matched healthy controls (5 males and 8 females) were recruited. Among 18 stroke patients, 8 had significant ICA stenosis (> 50%) and 10 had nonsignificant ICA stenosis (< 50%). During handgrip task, stroke patients and normal controls were allowed to use their hands coincided with infarction and right hands, respectively.

RESULTS

The mean BOLD signals in patients with significant ICA stenosis were significantly less than that in patients with nonsignificant ICA stenosis. Mean arterial pressure (MAP) was significantly correlated with activated voxels of Brodmann area 4 (P < 0.01) and total activated voxels (P  =  0.007), whereas hemoglobin and HbA1c showed no significant correlation with activated voxels of Brodmann area 4 or total activated voxels (P > 0.05).

CONCLUSION

It is suggested that both ICA stenosis and arterial BP could influence BOLD signal, while HbA1c and hemoglobin level had no effect on BOLD signal.

Pharmacological characterization of the mechanisms involved in the vasorelaxation induced by progesterone and 17β-estradiol on isolated canine basilar and internal carotid arteries

Progesterone and 17β-estradiol induce vasorelaxation through non-genomic mechanisms in several isolated blood vessels; however, no study has systematically evaluated the mechanisms involved in the relaxation induced by 17β-estradiol and progesterone in the canine basilar and internal carotid arteries that play a key role in cerebral circulation. Thus, relaxant effects of progesterone and 17β-estradiol on KCl- and/or PGF2α-pre-contracted arterial rings were investigated in absence or presence of several antagonists/inhibitors/blockers; the effect on the contractile responses to CaCl2 was also determined. In both arteries progesterone (5.6-180 μM) and 17β-estradiol (1.8-180 μM): (1) produced concentration-dependent relaxations of KCl- or PGF2α-pre-contracted arterial rings; (2) the relaxations were unaffected by actinomycin D (10 μM), cycloheximide (10 μM), SQ 22,536 (100 μM) or ODQ (30 μM), potassium channel blockers and ICI 182,780 (only for 17β-estradiol). In the basilar artery the vasorelaxation induced by 17β-estradiol was slightly blocked by tetraethylammonium (10mM) and glibenclamide (KATP; 10 μM). In both arteries, progesterone (10-100 μM), 17β-estradiol (3.1-31 μM) and nifedipine (0.01-1 μM) produced a concentration-dependent blockade of the contraction to CaCl2 (10 μM-10mM). These results suggest that progesterone and 17β-estradiol produced relaxation in the basilar and internal carotid arteries by blockade of L-type voltage dependent Ca(2+) channel but not by genomic mechanisms or production of cAMP/cGMP. Potassium channels did not play a role in the relaxation to progesterone in both arteries or in the effect of 17β-estradiol in the internal carotid artery; meanwhile KATP channels play a minor role on the effect of 17β-estradiol in the basilar artery.

Alterations in the gray matter volume in transient ischemic attack: a voxel-based morphometry study

BACKGROUND

Several studies have emphasized that transient ischemic attack (TIA) patients suffered functional impairments, but whether underlying morphological alterations exist remains unclear. This study aims to detect possible gray matter volume (GMV) alterations in patients with TIA using voxel-based morphometry (VBM) method.

METHODS

High-resolution T1-weighted anatomical images of 21 patients were compared with 21 healthy controls of matching age, gender, and education. Changes in the GMV were observed using VBM technique, followed by two-sample t-test analysis to detect the differences in the GMV between TIA patients and healthy controls. Correlations between the clinical parameters and the Montreal cognitive assessment (MoCA) scores, and the altered GMV in TIAs, were investigated.

RESULTS

Two-sample t-test analysis revealed a significant GMV reduction in specific regions in the default mode network (DMN) in TIA patients, including the bilateral medial frontal gyrus, anterior cingulate cortex (ACC), and precuneus. No correlation was found between the reduced GMV and MoCA scores and clinical parameters.

CONCLUSION

Transient ischemic attack patients showed widespread morphology atrophy in DMN, suggesting that, despite the absence of a cerebral infarction, ischemic injury may induce structural abnormalities and eventually contribute to functional impairments in TIA patients. Our results may provide a valuable basis for the pathophysiological mechanism related to the cognitive dysfunction of TIA from the view of brain morphology.

Cerebrovascular accident under anesthesia during dental surgery

Stroke, or cerebrovascular accident (CVA), is a medical emergency that may lead to permanent neurological damage, complications, and death. The rapid loss of brain function due to disruption of the blood supply to the brain is caused by blockage (thrombosis, arterial embolism) or hemorrhage. The incidence of CVA during anesthesia for noncardiac nonvascular surgery is as high as 1% depending on risk factors. Comprehensive preoperative assessment and good perioperative management may prevent a CVA. However, should an ischemic event occur, appropriate and rapid management is necessary to minimize the deleterious effects caused to the patient. This case report describes a patient who had an ischemic CVA while under general anesthesia for dental alveolar surgery and discusses the anesthesia management.

Association between carotid artery occlusion and ultrasonographic plaque type

BACKGROUND

Internal carotid artery (ICA) occlusion is associated with acute stroke and carries significant morbidity and mortality. The aim of this study was to examine whether ultrasonographic carotid plaque type may be associated with ICA occlusion.

METHODS

Two hundred eleven patients (85% men, mean age 66.0±9.5 years, 28.9% asymptomatic) with ICA occlusion were included in this case-control study. Ultrasonographic Gray-Weale plaque type (I-IV, echolucent to echogenic) characterization was obtained in both the occluded and the contralateral ICA. Univariate and conditional logistic regression analyses with 1:1 pair matching per artery were undertaken. Each contralateral carotid artery with stenosis was treated as control to the ipsilateral-occluded ICA of the same patient.

RESULTS

A total of 261 ICAs (61.9%) were recorded with type I-II plaque, of which 165 (63.2%) were among the occluded and 96 (36.8%) were among the contralateral ICAs with stenosis (P<0.001). Mean contralateral ICA stenosis was 58.2%±20.4%. Regression analysis showed that carotid plaque type I-II was significantly associated with carotid artery occlusion compared with plaque type III-IV (crude odds ratio [OR]=4.29, 95% confidence intervals [CI]=2.81-6.57%, P<0.001, adjusted OR=5.60, 95% CI=3.23-9.70, P<0.001). Previous neurological events did not seem to be significantly associated with plaque echolucency (OR=0.62, 95% CI=0.29-1.35, P=0.23).

CONCLUSIONS

A significant association between echolucent plaque and ICA occlusion was observed. This observational hypothesis may prompt for further investigation of the causal mechanism between carotid plaque type and ICA occlusion by larger cohort studies.

Endovascular treatment of carotid occlusive disease

Carotid occlusive disease is one of several etiologic factors for stroke. Of all strokes, an estimated 88% are ischemic in nature. Less than 20% of these are caused by atheroma in the carotid bifurcation. Traditionally, carotid artery stenosis has been treated with carotid endarterectomy (CEA); however, carotid artery balloon angioplasty and stent placement has enjoyed significant technological advances over the last decade and can now offer a comparable treatment alternative to CEA. In this review, the authors concentrate their discussion on the treatment of carotid atherosclerotic disease with particular attention on the endovascular treatment.

Middle cerebral artery pulsatility index and cognitive improvement after carotid endarterectomy for symptomatic stenosis

OBJECT

Transcranial Doppler (TCD) is frequently used to evaluate peripheral cerebral resistance and cerebral blood flow (CBF) in the middle cerebral artery prior to and during carotid endarterectomy (CEA). Patients with symptomatic carotid artery stenosis may have reduced peripheral cerebral resistance to compensate for inadequate CBF. The authors aim to determine whether symptomatic patients with reduced peripheral cerebral resistance prior to CEA demonstrate increased CBF and cognitive improvement as early as 1 day after CEA.

METHODS

Fifty-three patients with symptomatic CEA were included in this observational study. All patients underwent neuropsychometric evaluation 24 hours or less preoperatively and 1 day postoperatively. The MCA was evaluated using TCD for CBF mean velocity (MV) and pulsatility index (PI). Pulsatility index ≤ 0.80 was used as a cutoff for reduced peripheral cerebral resistance.

RESULTS

Significantly more patients with baseline PI ≤ 0.80 exhibited cognitive improvement 1 day after CEA than those with PI > 0.80 (35.0% vs 6.1%, p = 0.007). Patients with cognitive improvement had a significantly greater increase in CBF MV than patients without cognitive improvement (13.4 ± 17.1 cm/sec vs 4.3 ± 9.9 cm/sec, p = 0.03). In multivariate regression model, a baseline PI ≤ 0.80 was significantly associated with increased odds of cognitive improvement (OR 7.32 [1.40-59.49], p = 0.02).

CONCLUSIONS

Symptomatic CEA patients with reduced peripheral cerebral resistance, measured as PI ≤ 0.80, are likely to have increased CBF and improved cognitive performance as early as 1 day after CEA for symptomatic carotid artery stenosis. Revascularization in this cohort may afford benefits beyond prevention of future stroke. Clinical trial registration no: NCT00597883 ( ClinicalTrials.gov ).

Cerebrovascular reserve and stroke risk in patients with carotid stenosis or occlusion: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Impairments in cerebrovascular reserve (CVR) have been variably associated with increased risk of ischemic events and may stratify stroke risk in patients with high-grade internal carotid artery stenosis or occlusion. The purpose of this study is to perform a systematic review and meta-analysis to summarize the association of CVR impairment and stroke risk.

METHODS

We performed a literature search evaluating the association of impairments in CVR with future stroke or transient ischemic attack in patients with high-grade internal carotid artery stenosis or occlusion. We included studies with a minimum of 1-year patient follow-up with baseline CVR measures performed by any modality and primary outcome measures of stroke and/or transient ischemic attack. A meta-analysis with assessment of study heterogeneity and publication bias was performed. Results were presented in a forest plot and summarized using a random-effects model.

RESULTS

Thirteen studies met the inclusion criteria, representing a total of 1061 independent CVR tests in 991 unique patients with a mean follow-up of 32.7 months. We found a significant positive relationship between impairment of CVR and development of stroke with a pooled random effects OR of 3.86 (95% CI, 1.99-7.48). Subset analysis showed that this association between CVR impairment and future risk of stroke/transient ischemic attack remained significant regardless of ischemic outcome measure, symptomatic or asymptomatic disease, stenosis or occlusion, or CVR testing method.

CONCLUSIONS

CVR impairment is strongly associated with increased risk of ischemic events in carotid stenosis or occlusion and may be useful for stroke risk stratification.

Surgical results of the Carotid Occlusion Surgery Study

OBJECT

The Carotid Occlusion Surgery Study (COSS) was conducted to determine if superficial temporal artery-middle cerebral artery (STA-MCA) bypass, when added to the best medical therapy, would reduce subsequent ipsilateral stroke in patients with complete internal carotid artery (ICA) occlusion and an elevated oxygen extraction fraction (OEF) in the cerebral hemisphere distal to the occlusion. A recent publication documented the methodology of the COSS in detail and briefly outlined the major findings of the trial. The surgical results of the COSS are described in detail in this report.

METHODS

The COSS was a prospective, parallel-group, 1:1 randomized, open-label, blinded-adjudication treatment trial. Participants, who had angiographically demonstrated complete occlusion of the ICA causing either a transient ischemic attack or ischemic stroke within 120 days and hemodynamic cerebral ischemia indicated by an increased OEF measured by PET, were randomized to either surgical or medical treatment. One hundred ninety-five patients were randomized: 97 to the surgical group and 98 to the medical group. The surgical patients underwent an STA-MCA cortical branch anastomosis.

RESULTS

In the intention-to-treat analysis, the 2-year rates for the primary end point were 21% for the surgical group and 22.7% for the medical group (p = 0.78, log-rank test). Fourteen (15%) of the 93 patients who had undergone an arterial bypass had a primary end point ipsilateral hemispheric stroke in the 30-day postoperative period, 12 within 2 days after surgery. The STA-MCA arterial bypass patency rate was 98% at the 30-day postoperative visit and 96% at the last follow-up examination. The STA-MCA arterial bypass markedly improved, although it did not normalize, the level of elevated OEF in the symptomatic cerebral hemisphere. Five surgically treated and 1 nonsurgically treated patients in the surgical group had a primary end point ipsilateral hemispheric stroke after the 30-day postoperative period. No baseline characteristics or intraoperative variables revealed those who would experience a procedure-related stroke.

CONCLUSIONS

Despite excellent bypass graft patency and improved cerebral hemodynamics, STA-MCA anastomosis did not provide an overall benefit regarding ipsilateral 2-year stroke recurrence, mainly because of a much better than expected stroke recurrence rate (22.7%) in the medical group, but also because of a significant postoperative stroke rate (15%). Clinical trial registration no.: NCT00029146.

Natural history of carotid artery occlusion

Carotid artery occlusion (CAO) is a risk factor for stroke ipsilateral to the occlusion and puts patients in a high-risk category when contralateral endarterectomy is performed. The purpose of this study was to evaluate the long-term outcomes of patients with internal CAO and to determine risk factors predictive of subsequent neurological event, contralateral carotid intervention, or death. Patients with internal CAO shown by duplex ultrasonography were retrospectively identified and followed between January 2002 and June 2010 (follow-up: 1-101 months, mean: 52 months) at a tertiary care hospital. All had multiple duplex examinations available for review. Chi-square analysis was used to determine risk factors for neurologic event, contralateral intervention, or all-cause morality. Multivariate Cox proportional hazard analysis was conducted using univariate risk factors with P values <0.1. Survival was estimated using the Kaplan-Meier method (P < 0.05 significant). Eighty patients with internal CAO were identified and available for analysis. On initial encounter, 30 (38%) were symptomatic, with 26 (87%) having symptoms referable to the side of the occluded internal carotid artery. During follow-up, seven (9%) had a neurologic event, of which six (86%) were referable to the occluded side; 14 (18%) patients underwent a contralateral operation. Nineteen (24%) patients died during the period of study. Although numerous variables of multivessel disease were significant with χ(2) analysis, there was no significant risk factor associated with neurologic event on multivariate analysis. However, the development of a hemodynamically significant stenosis (>50%) or occlusion of the external carotid artery (ECA) ipsilateral to the occlusion on follow-up (P < 0.027) was associated with increased risk of death. Kaplan-Meier analysis showed 7-year survival for patients with ECA disease at follow-up was significantly worse (16.2% ± 10.3% [n = 21] vs. 79% ± 8.7% [n = 59]; P < 0.00001). Frequently, patients present with neurological symptoms referable to the side of the internal CAO. Eighty-six percent of neurologic events that occur in follow-up are attributable to the side of the occluded carotid, indicating that the occluded side continues to contribute to neurologic morbidity over time. Multivariate analysis revealed no single factor to be predictive of subsequent neurologic events. With significant risk of death in patients found to have ipsilateral ECA stenosis during follow-up, it seems reasonable to continue surveillance of the occluded carotid.

Cerebral hemodynamic benefits after contralateral carotid artery stenting in patients with internal carotid artery occlusion

CEA contralateral to an ICA occlusion is considered a surgical risk, and CAS may be an alternative for these patients. Our goal was to examine whether CAS improves cerebral hemodynamics on the treated side and on the side of the ICA occlusion, on the basis of measurement of CBF and CVR by using SPECT. The subjects were 8 patients who underwent contralateral CAS. Resting CBF and CVR to acetazolamide were measured by using (123)I-IMP SPECT before and chronically (3-6 months) after CAS. Resting CBF was also measured immediately (<2 hours) after CAS by using (123)I-IMP SPECT. There were no significant differences in resting CBF in both hemispheres immediately after CAS. However, resting CBF and CVR both significantly increased in the chronic period in both hemispheres. Contralateral CAS in patients with ICA occlusion resulted in cerebral hemodynamic improvement on the treated side and on the side of ICA occlusion.

A comparative study of perfusion CT and 99m Tc-HMPAO SPECT measurement to assess cerebrovascular reserve capacity in patients with internal carotid artery occlusion

Background and purpose

Patients with internal carotid artery (ICA) occlusion can demonstrate impaired cerebral vascular reserve (CVR). The detection of CVR using single photon emission CT (SPECT) is nowadays widely accepted as a predictor in the diagnostic pathway in patients considered for cerebral revascularization. Recently perfusion CT (PCT) gained widely acceptance in stroke imaging The present study was aimed at comparing the results of perfusion CT (PCT) and ^99mTc-HMPAO SPECT with acetazolamide challenge in patients with ICA occlusion.

Methods

13 patients were included in the prospective evaluation. Both PCT and ^99mTc-HMPAO SPECT were performed before and after the administration of acetazolamide. In detail, regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), adapted time to peak (Tmax) and mean transit times (MTT) were compared with SPECT data.

Results

^99mTc-HMPAO SPECT demonstrated an impairment of CVR in six patients. A preserved CVR was present in seven patients. All patients with impaired CVR proven by SPECT had a delayed MTT (mean +2.98 s) and a delayed Tmax (mean + 5.9 s), (both p < 0.005 compared with the non occluded side). 66% of patients with impaired CVR in SPECT showed a complete correlation of Tmax measurements in PCT with a high positive predictive value (PPV: 88.8%).

Conclusion

The prospective study demonstrated a highly significant correlation of perfusion parameters as' detected by ^99mTc-HMPAO SPECT and the Tmax as detected by PCT in patients with ICA occlusion. Therefore this easy-to-perform technique seems to be an adequate method for the evaluation of cerebral perfusion in patients with ICA occlusion.

Bypass for the prevention of ischemic stroke

OBJECTIVE

Although most ischemic strokes are thromboembolic in origin and their management is endovascular or medical, some are hemodynamic in origin and their management may be surgical. Extracranial-intracranial bypass with superficial temporal artery-to-middle cerebral artery (MCA) bypass, high-flow interposition grafts, and reconstructive techniques have been developed. Clinical indications and efficacy are controversial, and this review examines current practices.

METHODS

Bypass surgery is indicated for patients with athero-occlusive disease that results in chronic, low cerebral blood flow accompanied by episodes of ischemic symptoms. Specific diagnoses include: (1) internal carotid artery occlusion; (2) MCA occlusion and, rarely, high-grade MCA stenosis; (3) vertebrobasilar atherosclerotic steno-occlusive disease; (4) vasculitis resulting in severe occlusive disease; and (5) moyamoya disease.

RESULTS

Discouraging results from the Extracranial-Intracranial Bypass Trial demonstrated the importance of selecting surgical patients based on objective measures of hemodynamic insufficiency. Two such tests are xenon-enhanced computed tomography with acetazolamide challenge and positron emission tomography with measurement of oxygen extraction fraction. Perfusion computed tomography may be another, more practical test. Surgical series, systematic reviews of the literature, and two new randomized clinical trials that use these diagnostic techniques reveal contradictory results. Although they demonstrate that bypass surgery has a morbidity rate of less than 5% and a patency rate of more than 95%, they have not proven a clear benefit.

CONCLUSIONS

Patients with athero-occlusive disease and symptoms of hemodynamic insufficiency have significant risk of stroke if left untreated or managed medically. On the other hand, surgical intervention lacks supporting evidence. Clinicians must individualize their management recommendations until additional data are published or further consensus develops.

Effect of stenting on cerebral CT perfusion in symptomatic and asymptomatic patients with carotid artery stenosis

BACKGROUND AND PURPOSE

The introduction of CAS has led to increased treatment of both symptomatic and asymptomatic patients with internal carotid stenosis. This study was performed to compare the effect of stent placement on cerebral perfusion in symptomatic and asymptomatic patients using CT perfusion.

MATERIALS AND METHODS

We included 45 patients with carotid artery stenosis of ≥70% who underwent arterial stent placement. Thirty-one patients were treated because of symptoms; 14 asymptomatic patients were treated before coronary artery bypass grafting. Patients underwent CTP before and after stent placement. We calculated MTT, CBV, and CBF, and derived relative numbers that compared treated with untreated hemispheres: ratios of CBV and CBF and difference in MTT. We compared the effect of carotid stent placement on cerebral perfusion in symptomatic and asymptomatic patients.

RESULTS

All perfusion parameters changed significantly after treatment in symptomatic patients: rCBF increased from 0.81 to 0.93 (P < .001), rCBV decreased from 1.02 to 0.95 (P < .05), and dMTT decreased from 1.29 to 0.14 (P < .001). In asymptomatic patients only, rCBF changed significantly with an increase from 0.92 to 1.03 (P < .05). When we compared symptomatic and asymptomatic patients before treatment, rCBF in symptomatic patients was significantly lower. The decrease of rCBV after treatment in symptomatic patients resulted in a significantly lower value than in asymptomatic patients.

CONCLUSIONS

Carotid artery stent placement improves blood flow in the affected hemisphere in symptomatic and asymptomatic patients. CBF before treatment is more strongly impaired in patients with symptomatic carotid stenosis. Compensatory hyperemia on the symptomatic side before treatment (rCBV > 1) turns into hypoxemia after treatment, suggesting impaired autoregulation in these patients.

Recurrent Amaurosis Fugax in a Patient after Stanford Type A Dissection Depending on Blood Pressure and Haemoglobin Level

Purpose. A transient painless monocular visual loss due to a decrease in retinal circulation—also known as “amaurosis fugax”—often precedes acute territorial cerebral ischaemia. The case we present underlines the importance of a comprehensive diagnostic workup in patients with amaurosis fugax. Case Report. A 44-year-old man who had suffered from a dissection of the ascending aorta (Stanford Type A) five months ago presented with recurrent monocular vision problems. Episodes with sectional vision loss mainly occurred in combination with low blood pressure levels. Furthermore, the haemoglobin level was chronically low (Hb 9.7 mg/dL), and the patient was by mistake on a simultaneous therapy with phenprocoumon and unfractionated heparin. Carotid artery duplex scanning revealed a high-grade stenosis of the proximal right common carotid artery. MR imaging corroborated hypoperfusion in brain area corresponding to the right MCA. Conclusion. Our patient is an example in whom transient retinal ischaemic attacks may originate from haemodynamic reasons.

Management of patients with atherosclerotic carotid occlusion

OPINION STATEMENT

• Patients with acute ischemic stroke due to atherosclerotic carotid artery occlusion (ACAO) should receive intravenous tissue plasminogen activator (alteplase) if they meet eligibility criteria of the National Institute of Neurological Disorders and Stroke (NINDS) or the European Cooperative Acute Stroke Study III (ECASS III). • Patients with acute stroke due to ACAO who are not eligible for intravenous tissue plasminogen activator should receive aspirin. Heparin or heparin-like drugs do not improve outcome and should not be used. • Therapy for prevention of recurrent stroke in patients with ACAO should consist of lifestyle modifications, risk factor intervention, and antiplatelet drugs. Warfarin is not indicated. • Extracranial-intracranial bypass surgery provides no benefit over medical therapy in preventing recurrent stroke in a general population of patients with ACAO or in any subgroups selected by clinical, arteriographic, or hemodynamic criteria. • Other surgical or endovascular procedures have no proven value in treating or preventing stroke due to ACAO. • Asymptomatic carotid occlusion has a benign prognosis and requires no specific treatment other than lifestyle modification and risk factor intervention.

Long-term follow-up of patients with asymptomatic occlusion of the internal carotid artery with good and impaired cerebral vasomotor reactivity

BACKGROUND

Cerebral hemodynamic status might be prognostic for either the symptomatic or asymptomatic course of carotid occlusive disease. It is determined by evaluating cerebral vasomotor reactivity (VMR). We assessed VMR in asymptomatic patients with total occlusion of the internal carotid artery (ICA) and followed them to evaluate the role of impaired VMR in predicting ischaemic stroke (IS).

METHODS

Thirty-five patients (21 men, mean age ± SD 68 ± 7.5 years) with unilateral asymptomatic ICA occlusion were studied by transcranial Doppler and the Diamox test (intravenous 1.0 g acetazolamide) and followed for 48 months or until reaching the end-points of IS, transient ischaemic attack, or vascular death. VMR% was evaluated by recording the percent differences in peak systolic blood flow velocities in each middle cerebral artery at baseline and after Diamox administration.

RESULTS

Based on VMR% calculations, 14 (40%) patients had good VMRs and 21 (60%) had impaired VMRs. The global annual risk of ipsilateral ischaemic events was 5.7%. The annual ipsilateral ischaemic event risk was 1.8% in patients with good VMRs, whilst it was 7.1% in patients with impaired VMRs. An impaired VMR was significantly correlated with ipsilateral IS (Kaplan-Meier log rank statistic, P = 0.04).

CONCLUSIONS

Our results support the value of VMR assessment for identifying asymptomatic patients with carotid occlusion who belong to a high-risk subgroup for IS. New trials using extracranial-to-intracranial bypass surgery in patients with asymptomatic ICA occlusion and impaired VMRs are warranted.

Extracranial-intracranial bypass in atherosclerotic cerebrovascular disease: report of a single centre experience

Despite the failure of the international extracranial-intracranial (EC-IC) bypass study in showing the benefit of bypass procedure for prevention of stroke recurrence, it has been regarded to be beneficial in a subgroup of well-selected patients with haemodynamic impairment. This report includes the EC-IC bypass experience of a single centre over a period of 14 years. All consecutive 72 patients with atherosclerotic occlusive cerebrovascular lesions associated with haemodynamic compromise treated by EC-IC bypass surgery were retrospectively reviewed. Pre-operatively, 61% of patients presented with minor stroke and the remaining 39% with recurrent transient ischemic attacks (TIAs) despite maximal medical therapy. Angiography revealed a unilateral internal carotid artery (ICA) stenosis/occlusion in 79%, bilateral ICA stenosis/occlusion in 15%, MCA stenosis/occlusion in 3% and other multiple vessel stenosis/occlusion in 3% of the cases. H(2)(15)O positron emission tomography (PET) or 99mTc-HMPAO SPECT with acetazolamide challenge was performed for haemodynamic evaluation of the cerebral blood flow (CBF). All the patients had impaired haemodynamics pre-operatively in terms of reduced regional cerebrovascular reserve capacity and rCBF. Standard STA-MCA bypass procedure was performed in all patients. A total of 68 patients with 82 bypasses were reviewed with a mean follow-up period of 34 months. Stroke recurrence took place in 10 patients (15%) resulting in an annual stroke risk of 5%. Improved cerebral haemodynamics was documented in 81% of revascularised hemispheres. Patients with unchanged or worse haemodynamic parameters had significantly more post-operative TIAs or strokes when compared to those with improved perfusion reserves (30% vs.5% of patients, p<0.05). In conclusion, EC-IC bypass procedure in selected patients with occlusive cerebrovascular lesions associated with haemodynamic impairment has revealed to be effective for prevention of further cerebral ischemia, when compared with a stroke risk rate of 15% reported to date in patients only under antiplatelet agents or anticoagulant therapy.

Regional partition coefficient of water in patients with cerebrovascular disease and its effect on rCBF assessment

OBJECTIVE

Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF assessment.

METHODS

The study protocol included 22 patients with occlusive cerebrovascular disease to compare the partition coefficients among three regions (infarction area, noninfarct hypoperfusion area, and contralateral area) in the pathological brain (analysis A), and to compare the CBF estimated by using a fixed partition coefficient and CBF estimated using floating partition coefficients (analysis B).

RESULTS

The partition coefficient in the infarction area (0.55±0.07 ml/g) was lower than that in the contralateral normal cortex (0.68±0.05 ml/g), whereas noninfarct hypoperfusion area did not show a significant change (0.67±0.06 ml/g). As a result, the use of a fixed partition coefficient of normal volunteers (0.70 ml/g) resulted in an underestimation in regional CBF by 12% in infarction area (P<0.05), whereas the estimation errors were smaller and induced no significant difference in the noninfarct hypoperfusion area or in contralateral areas.

CONCLUSION

The partition coefficient is stable except for the infarction area, and CBF estimation using a fixed partition coefficient of normal volunteers provides clinically appreciable information in patients with cerebrovascular disease.

Haemodynamic stroke: clinical features, prognosis, and management

Haemodynamic stroke is a type of ischaemic stroke that is caused by hypoperfusion rather than by embolism or local vasculopathy. It can be caused by systemic diseases such as heart failure or hypotension, but also by severe obstruction of the carotid or vertebral arteries. Patients with haemodynamic stroke or transient ischaemic attack might show specific clinical features that distinguish them from patients with embolism or local small-vessel disease. Ancillary investigations of cerebral perfusion can show whether blood flow to the brain is compromised and provide important prognostic information. Management of patients who have hypoperfusion as the major cause of ischaemic stroke or as a contributing factor is hampered by the lack of clinical trials. Treatment aimed at increasing cerebral blood flow might be considered in selected patients on the basis of information from case series. Further research is needed to define criteria for the diagnosis of haemodynamic stroke and to investigate treatment options in controlled studies.

Transient ischemic attack: are there different types or classes? Risk of stroke and treatment options

Recent advances in neuroimaging have revolutionized the evaluation of the clinical syndrome of transient ischemic attack (TIA). Diffusion-weighted imaging demonstrates microinfarctions (< 1 cm(3)) in approximately 50% of patients with TIA, establishing that not all clinically transient spells are transient at the tissue level. The clinical syndrome of TIA that is associated with ischemic brain injury is called "transient symptoms with infarction" (TSI). TSI appears to be a different subset because it harbors higher risk of imminent stroke than "TIA with no infarction." Armed with the evidence of ischemia as the cause of transient spell, clinicians can pursue the most appropriate therapy for stroke prevention by targeting the underlying etiology of brain ischemia.

Neuro-ophthalmic manifestations of a complicated cholesteatoma

BACKGROUND

A cholesteatoma, also known as an epithelioma, is a mass of soft tissue that results from the accumulation of keratin protein debris enclosed by a layer of stratified squamous epithelium.

CASE REPORT

A patient with cholesteatoma surrounding both internal carotid arteries presented with cerebral ischemic symptoms expressed as visual and ocular symptoms. Because of its location, mass effect, and potential stenosis of the internal carotids, this slow-growing tumor is potentially sight threatening. Asymmetric cupping of the optic nerves associated with symptoms such as dizziness, diplopia, or facial pain should be worked up carefully.

CONCLUSION

The primary care optometrist can play an important role in the diagnosis and continued management of a patient with a cholesteatoma, carefully monitoring early signs of progression or change. This case illustrates how an intracranial lesion, away from the eye, can impact a number of ocular and visual functions.

Protected endovascular revascularization of subacute and chronic total occlusion of the internal carotid artery

BACKGROUND AND PURPOSE

The natural course of symptomatic carotid artery occlusion with hemodynamic impairment is poor. Surgical revascularization may improve the outcome; however, its efficacy has not been established yet. The goal of this study was to characterize the technical and clinical outcomes following endovascular recanalization of the ICA under cerebral circulatory protection.

MATERIALS AND METHODS

Endovascular recanalization was attempted in 8 patients with symptomatic ICA occlusions. The duration of the occlusion ranged from 7 days to 7 months (mean, 2.5 months), and the mean length of the occlusion was 95 mm. Cerebral hemodynamics ipsilateral to the side of the occlusion were severely impaired in all patients. The endovascular procedure was performed under total cerebral circulatory protection, beginning with proximal protection with a subsequent switch to distal protection after successful guidewire passage.

RESULTS

The occlusion was recanalized successfully in 7 of 8 patients (88%), resulting in improvement of ipsilateral cerebral hemodynamics without symptomatic stroke. Small asymptomatic ischemic lesions were detected in 6 of 8 patients (75%) on DWI, and 1 patient developed a mild groin hematoma. Ischemic episodes did not recur during the mean follow-up period of 19 months. However, 1 patient experienced asymptomatic reocclusion, which was re-treated successfully without complications, while another patient developed mild retinal hemorrhage at 3 months after the procedure due to the combination of antiplatelet and anticoagulant therapy.

CONCLUSIONS

Endovascular revascularization of an ICA occlusion is feasible and well-tolerated in patients with subacute or chronic total occlusion of the ICA.

Extracranial-intracranial arterial bypass surgery for occlusive carotid artery disease

BACKGROUND

The EC/IC Bypass Study Group found no benefit of extracranial to intracranial (EC/IC) bypass surgery over medical therapy in patients with symptomatic carotid artery occlusion (sCAO). However, the study was criticised for many reasons and the real effect of this treatment is still not known conclusively.

OBJECTIVES

To determine whether bypass surgery plus medical care is superior to medical care alone in patients with sCAO.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched June 2009). In addition, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2006), MEDLINE (1966 to June 2009) and EMBASE (1980 to June 2009). We also searched ongoing trials and research registers, checked reference lists of relevant articles, and contacted colleagues, trial authors and researchers.

SELECTION CRITERIA

Randomised controlled trials (RCT) and non-random studies of EC/IC bypass surgery plus best medical treatment compared with best medical treatment alone to prevent subsequent stroke, improve cerebral haemodynamics and reduce dependency after stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, and extracted data items on the number of outcome events onto a data extraction form. We only analysed secondary outcomes if the study provided information on at least one primary outcome. We also used intention-to-treat analysis where possible.

MAIN RESULTS

We included 21 trials, including two RCTs, involving 2591 patients. For all endpoints, no benefit of EC/IC bypass surgery was shown either in the RCTs (any death: odds ratio (OR) 0.81, 95% confidence interval (CI) 0.62 to 1.05, P = 0.11; stroke: OR 0.99, 95% CI 0.79 to 1.23, P = 0.91; death and dependency: OR 0.94, 95% CI 0.74 to 1.21, P = 0.64), or in the non-RCTs (any death: OR 1.00, 95% CI 0.62 to 1.62, P = 0.99; stroke: OR 0.80, 95% CI 0.54 to 1.18, P = 0.25; death and dependency: OR 0.80, 95% CI 0.50 to 1.29, P = 0.37).

AUTHORS' CONCLUSIONS

EC/IC bypass surgery in patients with sCAO disease was neither superior nor inferior to medical care alone. However, most studies included patients irrespective of their cerebral haemodynamics. Participation in an ongoing RCT, which is restricted to patients with impaired haemodynamics, is recommended as these patients might benefit from bypass surgery.

PET in Cerebrovascular Disease

Investigation of the interplay between the cerebral circulation and brain cellular function is fundamental to understanding both the pathophysiology and treatment of stroke. Currently, PET is the only technique that provides accurate, quantitative in vivo regional measurements of both cerebral circulation and cellular metabolism in human subjects. We review normal human cerebral blood flow and metabolism and human PET studies of ischemic stroke, carotid artery disease, vascular dementia, intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage and discuss how these studies have added to our understanding of the pathophysiology of human cerebrovascular disease.