Cerebral microembolism in acute myocardial infarction

BACKGROUND AND PURPOSE: This study was undertaken to determine the frequency of cerebral microemboli (high-intensity transient signals; HITS) detected by transcranial Doppler (TCD) in patients with acute myocardial infarction (AMI) and to relate them to the various putative risk factors and clinical embolic events. METHODS: We investigated 112 consecutive patients within 72 hours of admission to an acute coronary care unit using TCD to monitor for cerebral microemboli. Twelve patients were excluded because of failure of ultrasound insonation. All patients had 2-dimensional echocardiograms within the study period. RESULTS: HITS were detected in 17% of patients, with significantly higher frequency in patients with reduced (<65%) left ventricular (LV) ejection fraction (P=0. 019), akinetic LV segments (P=0.002), and LV thrombus (P=0.015). A marginally significant (P=0.059) increase of HITS was found in patients with anterior AMI. Stroke was significantly more frequent in patients with cerebral microemboli (P=0.01). CONCLUSIONS: HITS were detected in 17% of patients in spite of adequate antithrombotic therapy and were increased in patients with reduced LV function, akinetic myocardial segments, and LV thrombus. They were present in all 3 patients with stroke and may represent a predictor of clinical embolic events.     

High intensity transient signals in patients with carotid stenosis may persist after carotid endarterectomy

BACKGROUND: This study was undertaken to elucidate the natural history of high intensity transient signals (HITS) after carotid endarterectomy (CEA) and to determine whether this differs between patients with and without HITS detected preoperatively. METHODS: A 30-min transcranial Doppler (TCD) recording was performed to detect HITS in 141 patients at 0-1 h, 2-3 h, 4-6 h and 24-36 h following CEA. 104 of these patients also had 30-min TCD monitoring within 48 h prior to CEA. RESULTS: In the preoperative HITS-negative group, the proportion with postoperative HITS fell from 53% at 0-1 h to 17% at 24-36 h. In the preoperative HITS-positive group, the proportion with postoperative HITS remained steady (43% at 0-1 h, 52% at 24-36 h). During the 24-36 h postoperative epoch, 11 of 21 (52%) of the preoperative HITS-positive group had at least one HITS compared to 11 of 66 (17%) of the preoperative HITS-negative group (p = 0.001). In a multiple logistic regression analysis, preoperative HITS was the only factor associated with persistent postoperative HITS. CONCLUSION: The proportion of cases with postoperative HITS diminished in the 24-36 h after CEA except for preoperative HITS-positive patients. About half of our patients undergoing CEA with preoperative HITS might have another embolic source.     

What determines good recovery in patients with the most severe strokes? The Copenhagen Stroke Study.

BACKGROUND AND PURPOSE: Even patients with the most severe strokes sometimes experience a remarkably good recovery. We evaluated possible predictors of a good outcome to search for new therapeutic strategies. METHODS: We included the 223 patients (19%) with the most severe strokes (Scandinavian Stroke Scale score <15 points) from the 1197 unselected patients in the Copenhagen Stroke Study. Of these, 139 (62%) died in the hospital and were excluded. The 26 survivors (31%) with a good functional outcome (Barthel Index >/=50 points) were compared with the 58 survivors (69%) with a poor functional outcome (Barthel Index <50 points). The predictive value of the following factors was examined in a multivariate logistic regression model: age; sex; a spouse; work; home care before stroke; initial stroke severity; blood pressure, blood glucose, and body temperature on admission; stroke subtype; neurological impairment 1 week after onset; diabetes; hypertension; atrial fibrillation; ischemic heart disease; previous stroke; and other disabling disease. RESULTS: Decreasing age (odds ratio [OR], 0.50 per 10-year decrease; 95% CI, 0.25 to 0.99; P=0.04), a spouse (OR, 3.1; 95% CI, 1.1 to 8. 8; P=0.03), decreasing body temperature on admission (OR, 1.8 per 1 degrees C decrease; 95% CI, 1.1 to 3.1; P=0.01), and neurological recovery after 1 week (OR, 3.2 per 10-point increase in Scandinavian Stroke Scale score; 95% CI, 1.1 to 7.8; P=0.01) were all independent predictors of good functional outcome. CONCLUSIONS: Patients with the most severe strokes who achieve a good functional outcome are generally characterized by younger age, the presence of a spouse at home, and early neurological recovery. Body temperature was a strong predictor of good functional outcome and the only potentially modifiable factor. We suggest that a randomized controlled trial be undertaken to evaluate whether active reduction of body temperature can improve the generally poor prognosis of patients with the most severe strokes.     

Should stroke victims routinely receive supplemental oxygen? A quasi-randomized controlled trial.

BACKGROUND AND PURPOSE: We sought to test the hypothesis that breathing 100% oxygen for the first 24 hours after an acute stroke would not reduce mortality, impairment, or disability. METHODS: Subjects admitted to the Central Hospital of Akershus, Norway, with stroke onset <24 hours before admittance were allocated to 2 groups by a quasi-randomized design using birth numbers. All patients with acute stroke admitted to hospital within 24 hours after a stroke were included and enrolled. Patients were allocated to a group that received supplemental oxygen treatment (100% atmospheres, 3 L/min) for 24 hours (n=292) or to the control group, which did not receive additional oxygen. Main outcome measures were 1-year survival, neurological impairment (Scandinavian Stroke Scale), and disability (Barthel Index) 7 months after stroke. RESULTS: One-year survival was 69% in the oxygen group and 73% in the control group (OR 0.82; 95% CI 0.57 to 1.19; P=0.30). Impairment scores and disability scores were comparable 7 months after stroke. Among patients with Scandinavian Stroke Scale (SSS) scores of >/=40, 82% in the oxygen group and 91% in the control group survived (OR 0. 45; 95% CI 0.23 to 0.90; P=0.023). For patients with SSS scores of <40, 53% in the oxygen group and 48% in the control group survived (OR 1.26; 95% CI 0.76 to 2.09; P=0.54). CONCLUSIONS: Supplemental oxygen should not routinely be given to nonhypoxic stroke victims with minor or moderate strokes. Further research is needed to give conclusive advice concerning oxygen supplementation for patients with severe strokes.     

Infarct volume,neurological severity and PAF binding to platelets of patients with acute cerebral ischemic stroke

Abstract

Studies show that Platelet Activating Factor (PAF) is involved in the cerebrovascular response to ischemia, and that its binding to platelets may change in stroke victims. The purpose of this study was to determine whether binding of PAF to platelets of stroke patients could serve as an index for determining the volume of ischemic strokes and severity of neurological presentation. Thirteen stroke patients and 21 healthy controls were studied. The neurological severity of these stroke patients was evaluated by the Scandinavian Stroke Scale. Infarct volume was assessed by planimetric measures of brain CT. PAF binding to platelets was determined by use of radiolabelled PAF. (3H)PAF binding to platelets of stroke patients was lower than in controls (149.58±46.11 and 212.1 ± 10.3 receptors cell-1, respectively, p<0.001) and was significantly correlated with infarct volume (r = - 0.606, p=0.014) and with neurological score (r = 0.527, p = 0.032). No correlation was observed between neurological score and infarct volume. The study confirms the involvement of PAF in the pathogenesis of brain ischemia and neuronal damage. It shows that PAF binding to platelets of stroke patients correlates both with the extent of neuronal damage and the associated neurological impairment, and may serve as an additional index in the assessment of stroke seventy and clinical outcome of stroke victims. [Neurol Res 1999; 21: 645-648]     

Stroke subtype is an age-independent predictor of first-year survival.

The short-term outcome after acute stroke is known to be strongly dependent on stroke subtype, especially favoring patients having suffered a lacunar stroke. The value of stroke subtypes as long-term predictors of survival has not been firmly established. We therefore examined the 1-year survival from acute stroke in the Klosterneuburg Stroke Data Bank, which since 1988 systematically collects data on acute stroke patients treated in one center in Lower Austria. The cumulative survival of 398 consecutive patients (mean age 67.7 +/- SD 11.6) 1 year after a first-ever stroke was not only adversely related to age but also appeared to be age independent when compared according to stroke subtypes. The cumulative survival rates (CSR) ranged from 88.7 [95% confidence interval (CI): 82-92] for lacunar strokes (n = 107) to 68.1 (CI: 50-79) for atherothrombotic strokes (n = 69). Cardiogenic embolism (n = 68) showed a CSR of 72.1 (CI: 61-83) similar to the group of cryptogenic strokes (n = 121, CSR: 74.4, CI: 67-82). The CSR for primary intracerebral hemorrhage (n = 33) was 68.8 (CI: 53-85). It is concluded that the comparatively favorable prognosis of lacunar strokes must be recognized in trials designed to evaluate efficacy in terms of 1-year mortality. Furthermore, as cryptogenic stroke has an almost identical survival rate when compared to strokes caused by cardiogenic embolism it may be assumed that a considerable number of strokes for which no cause can be found are, in fact, cardiogenic embolic.     

Comparison of monitoring techniques for intraoperative cerebral ischemia

OBJECTIVE: To prospectively compare somatosensory evoked potentials, electroencephalography (EEG) and transcranial Doppler ultrasound (TCD) for detection of cerebral ischemia during carotid endarterectomy (CEA). METHODS: Somatosensory evoked potentials and EEG recordings were attempted in 156 consecutive CEAs and TCD was also attempted in 91 of them. Recordings from all three modalities were obtained for at least 10 minutes before CEA, during CEA and for at least 15 minutes after CEA. Somatosensory evoked potentials peak-to-peak amplitude decrease of >50%, EEG amplitude decrease of >75%, and ipsilateral middle cerebral artery mean blood flow velocity (mean VMCAi) decrease >75% persisting for the entire period of internal carotid artery occlusion were individually considered to be diagnostic of cerebral ischemia. Clinical neurological examination was performed immediately prior to surgery and following recovery from general anaesthesia. RESULTS: Somatosensory evoked potentials, EEG, and TCD were successfully obtained throughout the entire period of internal carotid artery occlusion in 99%, 95%, and 63% of patients respectively. Two patients (1.3%) suffered intraoperative cerebral infarction detected by clinical neurological examination and subsequent magnetic resonance imaging. Somatosensory evoked potentials accurately predicted intraoperative cerebral infarction in both instances without false negatives or false positives, EEG yielded one false negative result and no false positive results and VMCAi one true positive, four false positive and no false negative results. Transcranial Doppler ultrasound detection of emboli did not correlate with postoperative neurological deficits. Nevertheless the sensitivity and specificity of each test was not significantly different than the others because of the small number of disagreements between tests. CONCLUSION: A >50% decrease in the cortically generated P25 amplitude of the median somatosensory evoked potentials, which persisted during the entire period of internal carotid artery occlusion, appears to be the most reliable method of monitoring for intraoperative ischemia in our hands because it accurately detected both intraoperative strokes with no false positive or false negative results.     

Cerebral microembolus detection in an unselected acute ischemic stroke population

OBJECTIVE: The aims of this study were firstly to determine prevalence, frequency, and clinical significance of cerebral microemboli in an unselected acute ischemic stroke population and secondly to examine how this information may improve ischemic stroke subtype classification. METHODS: We intended to perform transcranial Doppler (TCD) microembolus monitorings of the middle cerebral artery (MCA) in the symptomatic hemisphere for 45 min in 120 consecutive patients with internal carotid artery territory ischemia. The first examination was performed within 72 h from start of symptoms and the second 5 +/- 1 days later. Platelet and coagulation system activation were measured following TCD monitoring in 38 patients. The strokes were subtyped using the TOAST classification criteria, and the patients' clinical status was assessed at discharge using the Scandinavian Stroke Scale and the Barthel Index. RESULTS: Microembolus monitoring was technically possible in 83 (69.2%) of the 120 patients. Thirty-two (26.6%) patients had an inadequate temporal bone acoustic window or were too restless to allow long-time monitoring. In 5 (4.2%) patients the relevant MCA was occluded. Twenty-two (26.5%) of the 83 patients had microemboli despite the fact that over 90% were receiving an antiplatelet or an anticoagulant treatment. The mean frequency of microemboli was 6.7 +/- 13.6 per 45 min. Microemboli were more prevalent in assumed cardioembolic stroke than in other subtypes of ischemic stroke (p = 0.047). We found no association between the presence of cerebral microemboli and the clinical outcome or the parameters for platelet or coagulation system activation. The presence of microemboli was not associated with in-hospital deaths (p = 0.17), whereas MCA occlusion was (p = 0.01). CONCLUSIONS: Cerebral microemboli are frequent in unselected acute ischemic stroke patients despite antiplatelet or anticoagulant treatment. TCD detection of microemboli provides valuable pathophysiological information and may, therefore, improve current ischemic stroke subtype classification.     

Poststroke epilepsy: occurrence and predictors--a long-term prospective controlled study (Akershus Stroke Study)

PURPOSE: The aims of the study were to assess the occurrence of poststroke epilepsy (PSE) in patients with ischemic strokes, to identify predictors, and to investigate whether treatment in a stroke unit (SU) influenced the long-term outcomes of epilepsy. METHODS: Patients with PSE, defined as those having two ore more unprovoked epileptic seizures > or = 1 week after an ischemic stroke, were identified from a cohort of 484 patients with ischemic strokes. The patients were prospectively assessed 7-8 years after stroke or until death. Different variables were studied to look for possible predictors. RESULTS: From 484 patients with ischemic strokes, PSE developed in 12 (2.5%) and 15 (3.1%) patients during the first year and 7-8 years after stroke, respectively. Eight (53%) of these patients were treated in a stroke unit (SU), and seven (47%) were treated in a general medical ward (GMW). The mean age of those who developed PSE and those who did not was 74.3 years and 76.3 years, respectively. In a multivariate analysis, a Scandinavian Stroke Scale (SSS) score < 30 on admission was a significant predictor for developing PSE [odds ratio (OR), 4.9; p = 0.004). CONCLUSIONS: The prevalence of PSE, 7 to 8 years after an ischemic stroke, was 3.1%. SSS scores < 30 on admission were a significant predictor for PSE. Neither treatment in SU versus GMW, cortical location, nor age at onset of stroke seemed to influence the risk of developing PSE.     

Association of intraoperative transcranial doppler monitoring variables with stroke from carotid endarterectomy

BACKGROUND AND PURPOSE: The outcomes of carotid endarterectomy (CEA) are, in addition to patient baseline characteristics, highly dependent on the safety of the surgical procedure. During the successive stages of the operation, transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) was used to assess the association of cerebral microembolism and hemodynamic changes with stroke and stroke-related death. METHODS: By use of data pooled from 2 hospitals in the United States and the Netherlands, including 1058 patients who underwent CEA, the association of various TCD emboli and velocity variables with operative stroke and stroke-related death was evaluated by univariable and multivariable logistic regression analyses in combination with receiver operating characteristic (ROC) curve analyses. The impact of basic patient characteristics, such as age, sex, preoperative cerebral symptoms, and ipsilateral and contralateral internal carotid artery stenosis, on the prediction of operative stroke was also evaluated. RESULTS: We observed 31 patients with ischemic and 8 patients with hemorrhagic operative strokes. Four of these patients died. Emboli during dissection (odds ratio [OR] 1.5, 95% CI 0.8 to 2.9) and wound closure (OR 2.3, 95% CI 1.2 to 4.4) as well as > or =90% decrease of MCA peak systolic velocity at cross-clamping (OR 3.3, 95% CI 1.3 to 8.5) and > or =100% increase of the pulsatility index of the Doppler signal at clamp release (OR 7.1, 95% CI 1.4 to 35.7) were independently associated with stroke. The ROC area of this model was 0.69. Of the patient characteristics, only preoperative cerebral ischemia (OR 1.9, 95% CI 1.0 to 3.7) and > or =70% ipsilateral internal carotid artery stenosis (OR 0.5, 95% CI 0.2 to 0.9) were associated with stroke. Adding these patient characteristics to the model, the area under the ROC curve increased to 0.73. CONCLUSIONS: In CEA, TCD-detected microemboli during dissection and wound closure, > or =90% MCA velocity decrease at cross-clamping, and > or =100% pulsatility index increase at clamp release are associated with operative stroke. In combination with the presence of preoperative cerebral symptoms and > or =70% ipsilateral internal carotid artery stenosis, these 4 TCD monitoring variables reasonably discriminate between patients with and without operative stroke. This supports the use of TCD as a potential intraoperative monitoring modality to alter the surgical technique by enhancing a decrease of the risk of stroke during or immediately after the operation.     

Distribution of artificial cerebral microemboli in stroke patients with patent foramen ovale

Abstract

Objectives: Patent foramen ovale (PFO) is considered as an important risk factor for cerebrovascular diseases. Nevertheless, the relationship between the distribution of highintensity transient signals (HITS), resulting from injection of air mixed with saline and detected by transcranial Doppler (TCD), and clinical cerebrovascular syndromes in these patients has not been investigated.

Methods: Using TCD, we screened 40 patients with stroke or transient ischemic attack (TIA), in whom PFO was proven by transesophageal echocariography (TEE). Of these, 30 patients (75%) with artificially produced HITS either in the middle cerebral artery (MCA) or the basilar artery (BA) were included in the analysis.

Results: Nineteen patients had a stroke or TIA in the carotid territory and 11 patients in the vertebro-basilar territory. HITS were found in the MCA in all 30 patients and in 21 of the 30 patients in the BA. Of the latter, ten patients were in the carotid group and 11 patients were in the veretebro-basilar group, p=0.011.

Conclusion: There is a significant association between the distribution of artificial HITS and the clinical cerebrovascular syndromes.     

Distribution of artificial cerebral microemboli in stroke patients with patent foramen ovale

OBJECTIVES: Patent foramen ovale (PFO) is considered as an important risk factor for cerebrovascular diseases. Nevertheless, the relationship between the distribution of high-intensity transient signals (HITS), resulting from injection of air mixed with saline and detected by transcranial Doppler (TCD), and clinical cerebrovascular syndromes in these patients has not been investigated. METHODS: Using TCD, we screened 40 patients with stroke or transient ischemic attack (TIA), in whom PFO was proven by transesophageal echocariography (TEE). Of these, 30 patients (75%) with artificially produced HITS either in the middle cerebral artery (MCA) or the basilar artery (BA) were included in the analysis. RESULTS: Nineteen patients had a stroke or TIA in the carotid territory and 11 patients in the vertebro-basilar territory. HITS were found in the MCA in all 30 patients and in 21 of the 30 patients in the BA. Of the latter, ten patients were in the carotid group and 11 patients were in the veretebro-basilar group, p = 0.011. CONCLUSION: There is a significant association between the distribution of artificial HITS and the clinical cerebrovascular syndromes.     

Transcranial Doppler monitoring of cerebral embolism in atrial fibrillation and prosthetic valves. Clinical correlations

Transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) permits the detection of high intensity transient signals (HITS), which are believed to represent microemboli. Non-valvular atrial fibrillation (NVAF) and prosthetic heart valves (PV) are important risk factors for embolic stroke. We evaluated both the prevalence and the frequency of microemboli in these high risk groups and the correlation with previous stroke. Sixty-six patients were monitored for 30 min on both MCAs sequentially. Twenty healthy subjects were studied as well. The total number of HITS recorded on both sides, expressed as HITS/h, was used for comparison. In NVAF patients (n = 24) the prevalence of HITS was 25%, in PV (n = 16) 62% and in those patients in whom PV coexisted with atrial fibrillation (PVAF) (n = 26), it was 42%. None in the control group showed HITS. HITS occurred significantly more frequently in PVAF (12.3/h) than in both NVAF (1.4/h, p = 0.007) and PV (2.7/h, p = 0.011), whereas there was no difference between PV and NVAF. The prevalence of HITS was not statistically different in patients with and without previous stroke, but among HITS positive patients those with previous stroke had a significantly higher HITS frequency (18.9 vs 8.5/h, p = 0.04). In conclusion, in patients with cardiac embolic sources the frequency of HITS increases from the classes with the lower (NVAF, PV) to the class with the highest (PVAF) risk factor. Patients with previous stroke have more HITS than asymptomatic ones. Therefore, embolus detection monitoring seems a promising tool in the assessment of the individual stroke risk in patients with cardiac embolic sources.     

Nutritional status in acute stroke: undernutrition versus overnutrition in different stroke subtypes

Objectives – Nutritional status in the acute stage of stroke has not been properly evaluated in different stroke subtypes. The objective of this study was to investigate the nutritional status of different subtypes of stroke patients. Subjects and methods – We studied 88 female patients with first-ever strokes. Strokes were divided into cerebral infarction (CI, n =67) and intracerebral hemorrhage (ICH, n =21). We measured the nutritional status of the patients in the acute stage of stroke with the use of 8 parameters including 3 biochemical and 5 anthropometric ones. These variables were assessed in stroke patients and 120 age-matched controls, and were compared with each other. Results – In the acute stage of stroke, undernourishment was significantly ( P =0.000) more prevalent in the ICH group (62%) than in the CI group (25%) or controls (13%). On the other hand obesity was present in 10%, 24% and 17% in patients with ICH, those with CI, and controls, respectively, which was not significantly different ( P =0.461). Only abdominal skinfold thickness was significantly greater in patients with CI than in those with ICH or controls. Conclusions – Our results illustrate that undernourishment is prevalent in acute stroke patients, significantly more so in patients with ICH than in those with CI. Stroke patients, especially those with ICH, should receive special nutritional intervention starting immediately after admission.     

颈动脉内膜切除术防治缺血性脑血管病的近远期随访分析

目的 评价颈动脉内膜切除术防治缺血性脑血管病的近远期疗效。方法 14例有症状的重度颈动脉狭窄患者接受了颈动脉内膜切除术,对13例患者进行了3月～5年的随访。每位患者来院复查时行全面神经系统检查及TCD、颈动脉彩色多普勒超声检查,在随访过程中均行DSA检查1次。结果 13例随访病例在随访期间均无中风发生。除2例患者外,其余均无TIAs。TCD、颈动脉彩色多普勒超声检查和DSA检查发现2例再狭窄,其中1例无症状,另1例有TIAs,予内科保守治疗。结论 颈动脉内膜切除术是防治缺血性脑血管病的有效方法。多普勒超声检查是首选的有效的无创检查方法。TCD对病变的诊断有辅助作用。     

Carotid plaque features on angiography and asymptomatic cerebral microembolism

We studied 110 carotid arteries of 55 patients with unilateral or bilateral carotid stenosis diagnosed with selective angiography, by using Transcranial Doppler to detect high intensity transient signals (HITS) in the middle cerebral arteries (MCAs). HITS identified as embolic signals were prevalent ( P <0.05) in the MCAs on the same side as severe (70–99%) stenosis (22 of 51=43.1%) compared to moderate (30–69%) stenosis (5 of 37=13.5%). No HITS were observed in the MCA on the same side as normal control carotid arteries ( n =17) [occluded arteries ( n =5) were not considered]. HITS were more prevalent ( P <0.05) in the MCAs on the same side as ulcerated plaques (14 of 23=60.9%) compared to non-ulcerated plaques (13 of 65=20%), and all moderate stenoses producing HITS presented ulceration of the plaque. Ulcerated plaque groups showed a higher mean number of HITS than non-ulcerated plaque groups and no significant difference was noted between moderate and severe stenosis, between superficial or deep ulcerations and between ulcerations with flap or without flap. Therefore, severe carotid stenosis and moderate stenosis with plaque ulceration result in angiographic findings most frequently associated with HITS. Further studies are necessary to evaluate the clinical significance of this finding.     

Efficacy of aspirin plus extended-release dipyridamole in preventing recurrent stroke in high-risk populations

OBJECTIVE: To assess the efficacy of aspirin plus extended-release dipyridamole compared with aspirin alone for the prevention of recurrent stroke among high-risk groups. DESIGN: A post hoc analysis was conducted using data from the European Stroke Prevention Study 2. Rates of annual strokes and vascular events were determined for the aspirin plus extended-release dipyridamole group (n = 1650) and the aspirin-only group (n = 1649), and were stratified by risk subgroup and univariate risk factors. Stroke models from the Framingham Study and the Stroke Prognostic Instrument II were applied to subjects in the European Stroke Prevention Study 2 to categorize patients into risk groups. RESULTS: Compared with aspirin alone, aspirin plus extended-release dipyridamole demonstrated a more pronounced efficacy in reducing the risk for stroke and vascular events among patients younger than 70 years; those with hypertension, prior stroke, or transient ischemic attack; current smokers; and those with any prior cardiovascular disease. Relative hazard reductions favored the combination of aspirin plus extended-release dipyridamole, and were greatest for the high-risk Framingham Study group and the moderate-risk Stroke Prognostic Instrument II subgroup. CONCLUSION: Aspirin plus extended-release dipyridamole is more effective than aspirin alone at preventing stroke, and the difference in efficacy increases in higher-risk patients.     

Diagnostic accuracy of EEG changes during carotid endarterectomy in predicting perioperative strokes

The 30 day stroke rate following carotid endarterectomy (CEA) ranges between 2–6%. Such periprocedural strokes are associated with a three-fold increased risk of mortality. Our primary aim was to determine the diagnostic accuracy of electroencephalogram (EEG) in predicting perioperative strokes through meta-analysis of existing literature. An extensive search for relevant literature was undertaken using PubMed and Web of Science databases. Studies were included after screening using predetermined criteria. Data was extracted and analyzed. Summary sensitivity, specificity and diagnostic odds ratio were obtained. Subgroup analysis of studies using eight or more EEG channels was done. Perioperative stroke rate for the cohort of 8765 patients was 1.75%. Pooled sensitivity and specificity of EEG changes in predicting these strokes were 52% (95% confidence interval [CI], 43–61%) and 84% (95% CI, 81–86%) respectively. Summary estimates of the subgroup were similar. The diagnostic odds ratio was 5.85 (95% CI, 3.71–9.22). For the observed stroke rate, the positive likelihood ratio was 3.25 while the negative predictive value was 98.99%. According to these results, patients with perioperative strokes have six times greater odds of experiencing an intraoperative change in EEG during CEA. EEG monitoring was found to be highly specific in predicting perioperative strokes after CEA.     

Infarct volume, neurological severity and PAF binding to platelets of patients with acute cerebral ischemic stroke.

Studies show that Platelet Activating Factor (PAF) is involved in the cerebrovascular response to ischemia, and that its binding to platelets may change in stroke victims. The purpose of this study was to determine whether binding of PAF to platelets of stroke patients could serve as an index for determining the volume of ischemic strokes and severity of neurological presentation. Thirteen stroke patients and 21 healthy controls were studied. The neurological severity of these stroke patients was evaluated by the Scandinavian Stroke Scale. Infarct volume was assessed by planimetric measures of brain CT. PAF binding to platelets was determined by use of radiolabelled PAF. (3H)PAF binding to platelets of stroke patients was lower than in controls (149.58 +/- 46.11 and 212.1 +/- 10.3 receptors cell-1, respectively, p < 0.001) and was significantly correlated with infarct volume (r = -0.606, p = 0.014) and with neurological score (r = 0.527, p = 0.032). No correlation was observed between neurological score and infarct volume. The study confirms the involvement of PAF in the pathogenesis of brain ischemia and neuronal damage. It shows that PAF binding to platelets of stroke patients correlates both with the extent of neuronal damage and the associated neurological impairment, and may serve as an additional index in the assessment of stroke severity and clinical outcome of stroke victims.     

Big strokes in small persons

Sickle cell disease (SCD) is understood on a genetic and a molecular level better than most diseases. Young children with SCD are at a very high risk of stroke. The molecular pathologic abnormalities of SCD lead to microvascular occlusion and intravascular hemolytic anemia. Microvascular occlusion is related to painful episodes and probably causes microcirculatory problems in the brain. The most commonly recognized stroke syndrome in children with SCD is large-artery infarction. These "big strokes" are the result of a vascular process involving the large arteries of the circle of Willis leading to territorial infarctions from perfusion failure or possibly artery-to-artery embolism. We can detect children who are developing cerebral vasculopathy using transcranial Doppler ultrasonography (TCD) and can provide effective intervention. Transcranial Doppler ultrasonography measures blood flow velocity in the large arteries of the circle of Willis. Velocity is generally increased by the severe anemia in these patients, and it becomes elevated in a focal manner when stenosis reduces the arterial diameter. Children with SCD who are developing high stroke risk can be detected months to years before the stroke using TCD. Healthy adults have a middle cerebral artery velocity of approximately 60 cm/s, whereas children without anemia have velocities of approximately 90 cm/s. In SCD, the mean is approximately 130 cm/s. Two independent studies have demonstrated that the risk of stroke in children with SCD increases with TCD velocity. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) (1995-2000) was halted prematurely when it became evident that regular blood transfusions produced a marked (90%) reduction in first stroke. Children were selected for STOP if they had 2 TCD studies with velocities of 200 cm/s or greater. Children not undergoing transfusion had a stroke risk of 10% per year, which was reduced to less than 1% per year by regular blood transfusions. Stroke risk in all children with SCD is approximately 0.5% to 1.0% per year. On the basis of STOP, if the patient meets the high-risk TCD criteria, regular blood transfusions are recommended. A second study was performed (2000-2005) to attempt withdrawal of transfusion in selected children in a randomized controlled study. Children with initially abnormal TCD velocities (> or =200 cm/s) treated with regular blood transfusion for 30 months or more, which resulted in reduction of the TCD to less than 170 cm/s, were eligible for randomization into STOP II. Half continued transfusion and half had cessation of transfusion. This trial was halted early for safety reasons. There was an unacceptably high rate of TCD reversion back to high risk (> or =200 cm/s), as well as 2 strokes in children who discontinued transfusion. There are no evidence-based guidelines for the discontinuation of transfusion in children once they have been identified as having high risk based on TCD. The current situation is undesirable because of the long-term effects of transfusion, including iron overload. Iron overload has recently become easier to manage with the introduction of an oral iron chelator. The inflammatory environment known to exist in SCD and the known effect of plasma free hemoglobin, released by hemolysis, of reducing available nitric oxide may contribute to the development of cerebrovascular disease. Further research may lead to more targeted therapies. We can reduce many of the big strokes that occur in these small persons by aggressively screening patients at a young age (and periodically throughout the childhood risk period) and interrupting the process with regular blood transfusions.