Validation of an acute ischemic stroke model: does diffusion-weighted imaging lesion volume offer a clinically significant improvement in prediction of outcome?

BACKGROUND AND PURPOSE

Prediction models for ischemic stroke outcome have the potential to contribute prognostic information in the clinical and/or research setting. The importance of diffusion-weighted magnetic resonance imaging (DWI) in the prediction of clinical outcome, however, is unclear. The purpose of this study was to combine acute clinical data and DWI lesion volume for ischemic stroke patients to determine whether DWI improves the prediction of clinical outcome.

METHODS

Patients (N=382) with baseline DWI data from the Glycine Antagonist In Neuroprotection and citicoline (010 and 018) trials were used to develop the prediction models by multivariable logistic regression. Data from prospectively collected patients (N=266) from the Acute Stroke Accurate Prediction Study were used to externally validate the model equations. The models predicted either full recovery or nursing home-level disability/death, as defined by the National Institutes of Health Stroke Scale, Barthel Index, or modified Rankin Scale.

RESULTS

The full-recovery models with DWI lesion volume had areas under the receiver operating characteristic curves (AUCs) of 0.799 to 0.821, and those without DWI lesion volume had AUCs of 0.758 to 0.798. The nursing home-level disability/death models with DWI had AUCs of 0.832 to 0.882, and those without DWI had AUCs of 0.827 to 0.867. All models had mean absolute errors < or =0.4 for calibration.

CONCLUSIONS

All 12 models had excellent discrimination and calibration, with 8 of 12 meeting prespecified performance criteria (AUC > or =0.8, mean absolute error < or =0.4). Although DWI lesion volume significantly increased model explanatory power, the magnitude of increase was not large enough to be clinically important.

is leukoaraiosis on CT an accurate surrogate marker for the presence of microbleeds in acute stroke patients?

Microbleeds (MB) detected on gradient echo magnetic resonance images (GRE) are a potential risk factor for intracerebral hemorrhage after thrombolysis or oral anticoagulation. We assessed whether the presence of MB could be predicted from the extent of white matter disease (WMD) on computed tomography (CT).

METHODS

We studied consecutive TIA or ischemic stroke patients who presented to the ER and who underwent both CT and GRE. WMD was rated on CT using a three point scale by two independent observers. The presence of MB was assessed on GRE. Logistic regression was used to predict the presence of MB on GRE.

RESULTS

199 consecutive patients underwent both CT and GRE. MB were identified on GRE in 56 patients (28.1%). After adjustment for age and sex, MB were more frequent in patients with leukoaraiosis (OR 2.8 per 1-point increase on the Van Swieten scale, p<0.001) and in patients presenting with a lacunar or posterior circulation syndrome (OR 2.0, p=0.048). The area under the ROC-curve derived from the logistic model was 0.70 (95% CI 0.61-0.79). Age, sex, hypertension, diabetes or the presence of left ventricular hypertrophy on ECG were not different in patients with or without MB.

CONCLUSION

White matter disease on CT is associated with the presence of microbleeds on GRE. However, leukoaraiosis does not detect the presence of MB accurately enough to be considered a surrogate marker.

Association of apolipoprotein E epsilon2 with white matter disease but not with microbleeds

BACKGROUND AND PURPOSE

Apolipoprotein E (apoE) alleles (epsilon2 and epsilon4) are associated with cerebral amyloid angiopathy, in which white matter disease and microbleeds are prominent features. The role of apoE in patients with microbleeds or white matter disease but no evidence of cerebral amyloid angiopathy has not been elucidated. We studied apoE alleles in relation to white matter disease and microbleeds in patients with transient ischemic attack or ischemic stroke.

METHODS

We obtained brain MRI scans and apoE genotypes in 334 transient ischemic attack or ischemic stroke patients. Microbleeds were scored on a gradient echo MRI and white matter disease was examined on fluid attenuated inversion recovery MRI using a semiquantitative rating scale.

RESULTS

Patients with moderate to severe white matter disease more frequently carried apoE epsilon2 alleles (25.2% versus 11.3%, P=0.001), but not apoE epsilon4 (26.6% in apoE epsilon4 carriers versus 25.9%; P=0.98). Adjustment for traditional risk factors did not modify this relationship (odds ratio, 2.9; 95% confidence interval, 1.5 to 5.3). There was no association between the presence of microbleeds and the apoE epsilon4 or apoE epsilon2 alleles.

CONCLUSIONS

ApoE alleles do not exert a major influence on the development of microbleeds, but apoE epsilon2 may be associated with development of moderate to severe white matter disease in transient ischemic attack and stroke patients.

Carotid angioplasty and stenting: caveat emptor!

Carotid endarterectomy effectively reduces stroke in patients with TIA or minor stroke and a high-grade carotid stenosis. Carotid endarterectomy is also beneficial in male asymptomatic patients younger than 75 years with high-grade stenosis. Carotid stenting has not been as thoroughly evaluated as carotid endarterectomy in randomized trials. The few trials that have been performed up to now show either inferior results or suggest equivalence. Before accepting carotid stenting as a mainstream treatment for carotid stenosis, this therapy should be as critically evaluated as carotid endarterectomy was in the 1980s and 1990s.

Body temperature and outcome after stroke thrombolysis

AIMS

We studied whether baseline body temperature and temperature increases after stroke adversely affect outcome after thrombolysis with intravenous tissue plasminogen activator (IV tPA).

METHODS

The evolution of body temperature in the first 24 h after treatment with IV tPA was described by calculating the area under the curve of the temperature over time plot relative to temperature at admission (AUCBL) and relative to a standard value of 37 degrees C (AUC37). Temperature parameters were related to functional outcome.

RESULTS

The median baseline National Institutes of Health Stroke Scale of 100 consecutive patients was 16 (interquartile range 11-21) and 34 patients had a favourable response to tPA. Patients with an unfavourable outcome had a more important temperature elevation than patients who had a favourable outcome after tPA (+1 degrees C vs +0.6 degrees C, P=0.02), despite similar baseline T and had a higher AUCBL (9.79 vs 5.36, P=0.027) and more frequently showed hyperthermia relative to baseline (82% vs 56%, P=0.011). After adjustment for baseline characteristics, the presence of hyperthermia relative to baseline was associated with a reduced odds of good outcome after thrombolysis (OR 0.34, 95% CI 0.10-0.95, P=0.040).

CONCLUSION

Hyperthermia relative to baseline temperature in the 24 h after intravenous thrombolysis is associated with an unfavourable outcome.

Risk of thromboembolism after cerebral venous thrombosis

The outcome of cerebral venous thrombosis (CVT) has been studied infrequently. We assessed the frequency of recurrence of cerebral or systemic thromboembolism and factors influencing recurrence. We performed a retrospective study of consecutive patients with CVT in the period 1985-2002 who were admitted to the University Hospital Gasthuisberg. We performed a chart review and a semi-standardized telephone interview that focused on recurrent CVT or systemic thromboembolism. Fifty-four CVT patients with a mean age of 42 years were followed up for a mean of 3.5 years. Eighty percent were women. Coagulation disorders were found in 17 patients (31%). One patient (1.9%) had recurrent CVT and seven patients (12.9%) suffered systemic thromboembolism after a median of 2.5 months. Patients with recurrent thromboembolism more often had coagulopathies (P = 0.04) or a history of deep venous thrombosis (P = 0.007). Patients with early recurrent venous thromboembolism often were not treated with oral anticoagulants (P < 0.001). It was evident from the above study that a substantial number of patients suffer recurrent thromboembolism after CVT.

The G93C mutation in superoxide dismutase 1: clinicopathologic phenotype and prognosis

BACKGROUND

Twenty percent of familial amyotrophic lateral sclerosis (ALS) is caused by mutations in the superoxide dismutase 1 gene (SOD1). Few data exist on their clinicopathologic phenotypes.

OBJECTIVES

To determine the clinical and pathologic phenotype associated with the G93C mutation in SOD1 and to compare survival in familial ALS related to this mutation with survival in other ALS subgroups.

DESIGN

Retrospective study.

SETTING

Tertiary referral center for neuromuscular disorders.

PATIENTS

Twenty patients with the G93C mutation for whom clinical data were available and 1 patient with pathologic data.

MAIN OUTCOME MEASURES

Characteristics and survival compared with other ALS subgroups, adjusting for known prognostic factors.

RESULTS

The G93C mutation was associated with a purely lower motor neuron phenotype without bulbar involvement. Presence of the mutation independently predicted longer survival compared with other ALS subgroups. Pathologic examination showed degeneration of the anterior horn, spinocerebellar tracts, and posterior funiculi, with minimal involvement of corticospinal tracts and no degeneration of brainstem motor nuclei. Survival motor neuron gene copy number had no significant influence on age at onset or survival in patients with the G93C mutation.

CONCLUSIONS

These findings add to the knowledge of SOD1-related familial ALS and demonstrate further clinicopathologic variability between different SOD1 mutations. Finally, they demonstrate the independent prognostic value of the G93C mutation.

Embolization of pulmonary arteriovenous malformations and decrease in prevalence of migraine

OBJECTIVE

To determine if embolization of pulmonary arteriovenous malformations (PAVMs) decreases the occurrence of migraine.

METHODS

All 105 patients with hereditary hemorrhagic telangiectasia (HHT), minimum age 16 years, who underwent an embolization of PAVM in our hospital between June 1995 and April 2004, were included in this study. A structured headache questionnaire was sent to all patients and focused on two periods: 1 year before and at least 6 months after embolization. Two independent neurologists diagnosed migraine according to the International Headache Society criteria.

RESULTS

Eighty-four patients (80%) sent back the questionnaire (mean age 47.8 +/- 15.1 years, 51 female). Median follow-up time was 48 months (first quartile: 23 months; third quartile: 66 months). The overall prevalence of migraine decreased from 45.2% before to 34.5% after embolization (p = 0.01). The prevalence of migraine with aura decreased from 33.3% before to 19.0% after embolization (p = 0.002). The severity of headache attacks decreased in patients who still had migraine (p = 0.15) or migraine with aura after embolization (p = 0.11).

CONCLUSION

Embolization of pulmonary arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia seems to be related to a decrease in prevalence of migraine, suggesting that the presence of a right-to-left shunt rather than the localization of this shunt plays a causative role in the pathogenesis of migraine.

Foundations of advanced magnetic resonance imaging

During the past decade, major breakthroughs in magnetic resonance imaging (MRI) quality were made by means of quantum leaps in scanner hardware and pulse sequences. Some advanced MRI techniques have truly revolutionized the detection of disease states and MRI can now-within a few minutes-acquire important quantitative information noninvasively from an individual in any plane or volume at comparatively high resolution. This article provides an overview of the most common advanced MRI methods including diffusion MRI, perfusion MRI, functional MRI, and the strengths and weaknesses of MRI at high magnetic field strengths.

The influence of percutaneous atrial septal defect closure on the occurrence of migraine

AIMS

Percutaneous patent foramen ovale closure seems to influence migraine. We wanted to observe the effect of percutaneous atrial septal defect (ASD) closure on migraine.

METHODS AND RESULTS

All patients (>16 years of age) with a percutaneous ASD closure were selected from our database (n=114). A questionnaire about headache before and after closure was sent. According to the criteria of the International Headache Society, two neurologists diagnosed migraine with and without aura (MA+ and MA-, respectively). McNemar paired chi(2) and Wilcoxon signed rank tests were used where applicable. Seventy-five patients (66%, 59 females, mean age 51+/-19 years) responded and were included in the study. An Amplatzer ASD occluder was used in all. Median follow-up time was 29 months (IQ1 and IQ3, 18 and 39 months, respectively). The prevalence of MA- and MA+ changed from 19 (14/75) and 11% (8/75), respectively, before closure to 12 (9/75) and 15% (11/75), respectively, after closure (P=0.18 and P=0.55, respectively, vs. before closure). In 12 patients who suffered from migraine before closure (n=4 and 8, MA+ and MA-, respectively), migraine disappeared. In this subgroup, the frequency of migraine attacks decreased significantly (P=0.01). New-onset migraine was noted in 10 patients (n=7 and 3, MA+ and MA-, respectively).

CONCLUSION

Percutaneous ASD closure was not related to a decrease in prevalence of migraine. In a subgroup, patients who suffered from typical migraine before ASD closure, the frequency of migraine attacks decreased significantly. The reason for the new-onset migraine remains unexplained. A larger study sample will be necessary to determine these findings.

What do we (not) know about the management of blood pressure in acute stroke?

Although it is indisputable that high blood pressure should be treated to prevent a first or a recurrent stroke, the management of high blood pressure in the first hours and days after stroke remains controversial. There is no high-quality evidence from randomized controlled trials to guide treatment in the 80% of patients who have elevated blood pressure during the first days after stroke. Theoretically, there are pros and cons for manipulating blood pressure after onset of stroke. Most treatment guidelines suggest leaving blood pressure untouched based on pathophysiologic principles. Post-hoc analyses from randomized trials, however, suggest that elevated blood pressure is associated with recurrent stroke and higher mortality, even after adjustment for potential confounders. On the other hand, preliminary studies have suggested that voluntarily increasing blood pressure might be beneficial in a selected subgroup of patients. In this overview, we present a summary of recent studies on this topic.

Extracranial carotid artery stenting in surgically high-risk patients using the Carotid Wallstent endoprosthesis: midterm clinical and ultrasound follow-up results

The purpose of this study was to evaluate the feasibility, safety and midterm outcome of elective implantation of the Carotid Wallstent in patients considered to be at high surgical risk. In a prospective study, 54 carotid artery stenoses in 51 patients were stented over a 24-month period. Three patients underwent bilateral carotid artery stenting. Institutional inclusion criteria for invasive treatment of carotid occlusive disease (carotid endarterectomy or carotid artery stenting) are patients presenting with a 70% or more symptomatic stenosis and those with an 80% or more asymptomatic stenosis having a life-expectancy of more than 1 year. All patients treated by carotid artery stenting were considered at high risk for carotid endarterectomy because of a hostile neck (17 patients--31.5%) or because of severe comorbidities (37 patients--68.5%). No cerebral protection device was used. Of the 54 lesions, 33 (61.1%) were symptomatic and 21 (38.8%) were asymptomatic. Follow-up was performed by physical examination and by duplex ultrasonography at 1 month, 6 months, 1 year and 2 years after the procedure. All 54 lesions could be stented successfully without periprocedural stroke. Advert events during follow-up (mean 13.9 +/- 5.7 months) were non-stroke-related death in 6 patients (11.1%), minor stroke in 4 stented hemispheres (7.4%), transient ipsilateral facial pain in 1 patient (1.8%), infection of the stented surgical patch in 1 patient (1.8%) and asymptomatic instent restenosis in 4 patients (7.4%). The percutaneous implantation of the Carotid Wallstent, even without cerebral protection device, appears to be a safe procedure with acceptable clinical and ultrasonographic follow-up results in patients at high surgical risk. But some late adverse events such as ipsilateral recurrence of non-disabling (minor) stroke or instent restenosis still remain real challenging problems.

VEGF is a modifier of amyotrophic lateral sclerosis in mice and humans and protects motoneurons against ischemic death

Amyotrophic lateral sclerosis (ALS) is an incurable degenerative disorder of motoneurons. We recently reported that reduced expression of Vegfa causes ALS-like motoneuron degeneration in Vegfa(delta/delta) mice. In a meta-analysis of over 900 individuals from Sweden and over 1,000 individuals from Belgium and England, we now report that subjects homozygous with respect to the haplotypes -2,578A/-1,154A/-634G or -2,578A/-1,154G/-634G in the VEGF promoter/leader sequence had a 1.8 times greater risk of ALS (P = 0.00004). These 'at-risk' haplotypes lowered circulating VEGF levels in vivo and reduced VEGF gene transcription, IRES-mediated VEGF expression and translation of a novel large-VEGF isoform (L-VEGF) in vivo. Moreover, SOD1(G93A) mice crossbred with Vegfa(delta/delta) mice died earlier due to more severe motoneuron degeneration. Vegfa(delta/delta) mice were unusually susceptible to persistent paralysis after spinal cord ischemia, and treatment with Vegfa protected mice against ischemic motoneuron death. These findings indicate that VEGF is a modifier of motoneuron degeneration in human ALS and unveil a therapeutic potential of Vegfa for stressed motoneurons in mice.

Coexistence of CADASIL and Alzheimer's disease

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is caused by point mutations in the Notch3 gene. Presenilins are proteins involved in the cleaving of both Notch and the amyloid precursor protein (APP). In cases of early onset Alzheimer's disease mutations of the presenilin genes (PSEN 1 and PSEN 2) and APP can be found. A 64 year old patient with CADASIL (R169C-mutation) is reported, who, in addition to subcortical infarcts and granular osmiophilic deposits, had numerous senile plaques and neurofibrillary tangles on pathological examination. Mutations in the APP, PSEN1, and PSEN2 genes were not identified. Neuropathological findings of Alzheimer's disease may be found in CADASIL patients.

Use of diffusion weighted MRI to predict the occurrence and severity of hemorrhagic transformation in a rabbit model of embolic stroke

Severe hemorrhagic transformation (HT) is an important complication of thrombolytic therapy. A method to identify stroke victims destined to severe HT could improve the patient selection and thus the safety of such treatment. In this study, we investigated whether very early serial diffusion weighted magnetic resonance imaging (DWI) could predict the occurrence of HT in an embolic model of experimental stroke. We tested the hypothesis that the ischemic brains with very low initial apparent diffusion coefficients (ADC) are destined to severe early (<or=5.5 h) HT. We retrospectively analyzed DWI scans of 45 New Zealand white rabbits subjected to thromboembolic stroke and treated with thrombolysis. DWI was obtained 0.5, 2, 3 and 5 h after embolization. Various thrombolytics were administered 1 h post embolization. The percentage of pixels within the ischemic hemisphere with ADC values below 550 x 10(-6) mm(2)/s was calculated and then compared to the severity of HT observed on gross brain sections at 5.5 h. As early as 30 min after embolization, ischemic brains destined to severe HT exhibited a significantly greater percentage of pixels below the cut-off value compared to those without HT: severe HT: 25%, 18.75-37.25% vs. no HT: 12%, 5.00-16.00% (median, 25th-75th %, P<0.001). Petechial HT when percentages were in the intermediate range. Quantitative analysis of initial ADC value might identify individual stroke patients at risk of severe HT.

Intermediate short-term outcomes after brain computed tomography and magnetic resonance imaging in neurology outpatients

OBJECTIVE

The purpose of this study was to assess and compare the impact of magnetic resonance imaging (MIR) and computed tomography (CT) on diagnostic and therapeutic decision making, taking into account the real cost of both techniques at the authors' institution.

METHOD

Brain CT and routine and rapid MRI were compared, and case files were prepared with either the CT or the MRI findings. These files were separately presented to a neurologist, and different questions were asked about further management. The real cost of CT and MRI was calculated. A questionnaire was sent to the patients 3 months after imaging.

RESULTS

More lesions were detected on MRI than on CT Routine and rapid AIRI were comparable. The analysis of the CT case files revealed an additional request for MRl in 33% of the patients. An analysis of the MRI case files revealed that 20% more technical examinations were requested after MRI than after CT In the majority of the patients (90%), neuroimaging had no impact on therapy except by means of reassurance of the physician. The scan was considered useful for therapeutic planning by excluding the presence of a space-occupying lesion. The real cost of the MP! strategy was 9% higher than that of the CT strategy.

CONCLUSION

In this patient population, neuroimaging was normal in the majority of the patients. Undergoing an imaging examination was of benefit to the patients and improved their sense of well-being mainly by the reassurance they experienced, as reported by 91% of the patients. At the authors' institution, the real cost of MMI in this patient population was only slightly higher than the real cost of CT The statistical analysis favors the use of MRI as a 1st imaging examination.

Demographic characteristics and prognosis in a Flemish amyotrophic lateral sclerosis population

We describe the genetic and demographic characteristics of patients with amyotrophic lateral sclerosis (ALS) in Flanders, Belgium. Prognostic factors related to survival are examined. ALS was familial in 8.6% of all MND patients. In 6 of 8 apparently unrelated families, an SOD1 mutation was found. In sporadic ALS, mean age at onset was 57.1 years. There was a male preponderance (1.2:1) and the disease had a bulbar onset in 19%. Median survival was 32 months (95% CI 26-46). The presence of an APOE-epsilon 4 allele was not associated with a bulbar onset of ALS, an earlier age at onset or a shorter median survival. Variables examined in a multivariate analysis included age, sex, site of onset, delay from onset to diagnosis, and % forced vital capacity. Shorter survival was independently associated with higher age, bulbar onset, a short diagnostic delay, and a lower percent-predicted vital capacity at study entry. Simple clinical baseline characteristics can assist the clinician in estimating prognosis in ALS. The demographic characteristics of the Flemish ALS population do not seem to differ from those described in other parts of the world.