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Laurent Derex

Publications and source records attributed to Laurent Derex.

16 recordsLinked to original sources
PubMed2006

Inflammatory response after ischemic stroke: a USPIO-enhanced MRI study in patients.

BACKGROUND AND PURPOSE: The intensity of the inflammatory response may be related to the volume of acute infarction. Ultra-small superparamagnetic particles of iron oxide (USPIO) may enable assessment of neuroinflammation. We aimed to assess whether the intensity of the inflammatory response might be related to the subacute ischemic lesion volume. METHODS: We enrolled patients who presented with acute anterior circulation stroke. MRI was performed at day 0, day 6, and day 9. The MRI protocol included T1-weighted imaging, gradient-echo T2*-weighted imaging, diffusion-weighted imaging, perfusion-weighted imaging and MR angiography. Blood-brain barrier disruption was defined as post-gadolinium enhancement on T1-weighted images. USPIO was administered after day 6 MRI. USPIO enhancement ratios were defined as the ratio between USPIO-related signal volume on day 9 T1-weighted imaging (respectively T2*-weighted imaging) and day 6 diffusion-weighted imaging infarct volume. The relationship between day 6 infarct volume and the enhancement ratio was assessed using Pearson and Spearman correlation tests. RESULTS: The protocol was completed in 10 patients. Signal alterations after USPIO injection was observed in 9/10 patients on day 9 T1-weighted imaging and in 5/10 patients on day 9 T2*-weighted imaging. USPIO-related MRI enhancement was heterogeneous. Lesion volume on day 6 diffusion-weighted imaging had no impact on USPIO enhancement at day 9 according to the Pearson correlation test (P=0.39) or Spearman test (P=0.25). There was no relationship between blood-brain barrier disruption and USPIO enhancement. CONCLUSIONS: USPIO MRI enhancement is heterogeneous and not clearly related to subacute lesion volume.

Aged↗
PubMed2006

Silent coronaropathy: usefulness of dobutamine stress echocardiography in ischemic stroke.

BACKGROUND: Several testing options are available to detect asymptomatic coronary artery disease (CAD). Dobutamine stress echocardiography (DSE) has been reported to increase the sensitivity and specificity of stress testing to detect CAD. Most studies concerned patients with known or suspected CAD who have a high pretest probability of disease. We aimed to perform a preliminary evaluation of DSE in atherothrombotic stroke. METHODS: Patients with transient ischemic attack or nondisabling ischemic stroke attributable to an atherothrombotic source were prospectively recruited. Patients with a history of angina pectoris or electrocardiographic signs of previous myocardial infarction were excluded. DSE was considered positive when regional reduction or deterioration of myocardial thickening developed in 1 segment. Coronary angiography was performed in patients with positive DSE. RESULTS: Sixty-four patients were recruited. Analysis of DSE was possible in 60 patients. Overall the test provided clinically useful information in 60/64 patients studied (>90%). DSE was positive in 9 patients (15%). Coronary angiography was performed in 8 patients, high-grade focal lesions were found in 3 patients, and 5 patients showed diffuse atheroma. Univariate logistic regression analysis showed that the main factor predictive of a positive DSE was the presence of an aortic arch atheroma (p = 0.003). Multivariate logistic regression analysis showed that two factors had an independent predictive value of positive DSE: aortic arch atheroma (p = 0.007) and dyslipidemia (p = 0.09). CONCLUSION: DSE may improve prevention of further vascular events in patients with an atherothrombotic source of ischemic stroke. This screening may be of particular benefit to patients with an aortic arch atheroma.

Adult↗
PubMed2006

Sinus venosus-type atrial septal defect: a rare curable cause of recurrent transient neurological deficits.

BACKGROUND AND PURPOSE: Sinus venosus defect is a rare cardiac abnormality, provoking an interatrial shunting outside the interatrial septum. Echographic diagnosis is difficult and may require examination by a specialized cardiologist. SUMMARY OF CASE: We report the case of a young woman who presented with repeated episodes of hemiparesis. CONCLUSIONS: Surgical correction of sinus venosus defect led to disappearance of neurological symptoms.

Adolescent↗
PubMed2006

A common basis for visual and tactile exploration deficits in spatial neglect?

One of the fundamental characteristics of spatial neglect is an imbalanced visual search behaviour favouring stimuli on the right side of space while largely ignoring those on the left side. Opinions differ as to whether this reflects a general orientational bias caused by impaired supramodal body-centred reference systems, or a modality-specific search disorder. A prediction of the former model would be that exploratory activity is similarly impaired both in vision and in the absence of visual control. We addressed this hypothesis by comparing patients' visual and tactile search in the same workspace. Our results show that the centre of exploration activity in both modalities was substantially shifted towards the ipsilesional right side in the neglect group as compared to healthy and patient controls. This bias was more accentuated for visual search. We found a clear linear relationship between the visual and tactile search biases in the patient group with spatial neglect. Our finding suggests that the critical component guiding search behaviour in neglect, whether visually or tactually, is a general rightward orientation bias. In addition, we observed an increased repetition rate in both modalities which affected the whole workspace. This implies that the apparent spatial working memory deficit dissociates from the mechanisms inducing the orientation bias.

Aged↗
PubMed2005

The vulnerable carotid artery plaque: current imaging methods and new perspectives.

BACKGROUND AND PURPOSE: Atherosclerosis is a diffuse, chronic inflammatory disorder that involves the vascular, metabolic, and immune systems and leads to plaque vulnerability. The traditional risk assessment relies on clinical, biological, and conventional imaging tools. However, these tools fall short in predicting near-future events in patients with vulnerable carotid artery plaque. METHODS: In current clinical practice, anatomic imaging modalities, such as B-mode ultrasound, spiral computed tomography angiography, and high-resolution MRI, can identify several morphological features characteristic of the vulnerable plaque but give little or no information regarding molecular and cellular mechanisms. RESULTS: This review is dedicated to factors involved in carotid artery plaque vulnerability and to new imaging methods that target this condition. Our aim is to describe the following: (1) conventional pathologic and imaging markers predictive of plaque vulnerability; (2) the role of relevant biological, genetic, and mechanical factors; (3) the potential of new imaging methods; and (4) current and emerging treatments. CONCLUSIONS: A multimodal assessment of plaque vulnerability involving the combination of systemic markers, new imaging methods that target inflammatory and thrombotic components, and the potential of emerging therapies may lead to a new stratification system for atherothrombotic risk and to a better prevention of atherothrombotic stroke.

Anticoagulants↗
PubMed2005

Ethical issues of informed consent in acute stroke. Analysis of the modalities of consent in 56 patients enrolled in urgent therapeutic trials.

BACKGROUND: Many patients may be mentally incompetent or physically unable to give informed consent at the acute stage of stroke. Accordingly, we aimed to investigate the modalities of informed consent in urgent therapeutic stroke trials, the awareness of patients and relatives regarding stroke clinical trials and the impact of decision making on patients and relatives. METHODS: We present a study of 56 acute ischemic stroke patients who were randomized in 4 trials (2 trials testing neuroprotective agents, 1 testing thrombolysis and 1 testing antithrombotic agents). A standardized questionnaire was used to assess the modalities of informed consent in this setting. RESULTS: The mean age was 67.1 (SD 12.6) years. The mean baseline Scandinavian Stroke Scale (SSS) score was 23.8 (SD 10.5). Only 13 patients (23% of cases) gave consent while relatives gave consent for 43 patients (77%). The main reason for not getting consent from the patient was aphasia in 29 patients (67.4%). Multiple logistic regression analysis showed that the two independent factors influencing the ability to give consent are age and baseline neurological deficit as assessed by the SSS score. Concerning the psychological impact of consent, none of the 10 patients who answered our questionnaire declared feeling uncomfortable when giving consent, while 7 out of the 13 relatives who could be reached declared they felt uncomfortable, mainly because of the psychological stress induced by urgent decision making. CONCLUSIONS: Our study emphasizes the specific ethical difficulties of informed consent in the setting of acute stroke research. Only a minority of patients are able to give consent at the acute stage. Increasing age and neurological deficit are independent predictors of inability to give consent. Thus, the responsibility for consent usually relies on relatives with potential inaccuracy of decision concerning the patient's wish or even conflict of interest. Further evaluation of the psychological impact of decision on relatives is needed in this setting of acute stroke.

Adult↗
PubMed2005

Evolution of lesion volume in acute stroke treated by intravenous t-PA.

PURPOSE: To determine the evolution of the ischemic lesion volumes in a population treated with tissue plasminogen activator (t-PA), MRIs were performed before treatment and 24 hours later; final infarct size was evaluated 60 days later. MATERIALS AND METHODS: A total of 42 patients with hemispheric stroke were recruited for a thrombolytic study. Intravenous t-PA was given after MRI within the first seven hours after stroke onset. Volumes were evaluated on day 0 and day 1 with diffusion-weighted imaging (DWI), on day 60 with T2-weighted imaging (T2WI), and recanalization was assessed based on day 1 MR angiography (MRA). RESULTS: Lesion volume increased between day 0 and day 1, and decreased between day 1 and day 60. It was lower in the group of patients with recanalization on day 1 MRA. CONCLUSION: Volume analysis emphasizes the effectiveness of recanalization as a predictive factor for better outcome, based on final infarct size. The decrease in lesion volumes between day 1 and day 60 suggests that other factors leads to overestimation of day 1 abnormal diffusion volume. This could explain the delayed partial reversibility of the DWI abnormality.

Brain↗
PubMed2004

Influence of pretreatment MRI parameters on clinical outcome, recanalization and infarct size in 49 stroke patients treated by intravenous tissue plasminogen activator.

We hypothesized that pretreatment magnetic resonance imaging (MRI) parameters might predict clinical outcome, recanalization and final infarct size in acute ischemic stroke patients treated by intravenous recombinant tissue plasminogen activator (rt-PA). MRI was performed prior to thrombolysis and at day 1 with the following sequences: magnetic resonance angiography (MRA), T2*-gradient echo (GE) imaging, diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI). Final infarct size was assessed at day 60 by T2-weighted imaging (T2-WI). The National Institutes of Health Stroke Scale (NIHSS) score was assessed prior to rt-PA therapy and the modified Rankin Scale (m-RS) score was assessed at day 60. A poor outcome was defined as a day 60 m-RS score >2. Univariate and multivariate logistic regression analyses were used to identify the predictors of clinical outcome, recanalization and infarct size. Forty-nine patients fulfilled the inclusion criteria. Baseline NIHSS score was the best independent indicator of clinical outcome (p=0.002). A worse clinical outcome was observed in patients with tandem internal carotid artery (ICA)+middle cerebral artery (MCA) occlusion versus other sites of arterial occlusion (p=0.009), and in patients with larger pretreatment PWI (p=0.001) and DWI (p=0.01) lesion volumes. Two factors predict a low rate of recanalization: a proximal site of arterial occlusion (p=0.02) and a delayed time to peak (TTP) on pretreatment PWI (p=0.05). The final infarct size was correlated with pretreatment DWI lesion volume (p=0.025). Recanalization was associated with a lower final infarct size (p=0.003). In conclusion, a severe baseline NIHSS score, a critical level of pretreatment DWI/PWI parameters and a proximal site of occlusion are predictive of a worse outcome after IV rt-PA for acute ischemic stroke.

Adult↗
PubMed2004

Magnetic resonance imaging: significance of early ischemic changes on computed tomography.

UNLABELLED: The significance of early ischemic changes (EICs) on CT remains controversial. MRI may provide relevant information in patients with EICs. METHODS: EICs were assessed in patients with acute ischemic stroke. MRI was promptly performed at presentation after CT and repeated on day 1. The relationship between EICs and MRI parameters was assessed with one-way ANOVA for analysis of continuous variables and by the chi2 test for the analysis of variables with a binary outcome. RESULTS: Fourty-eight patients underwent CT and MR imaging before treatment with recombinant tissue plasminogen activator (age: 63 +/- 14 years). EICs were graded as absent in 28 patients, <33% in 15 patients, and >33% of the middle cerebral artery (MCA) territory in 5 patients. NIHSS score was higher in patients with EICs that covered more than one third of the MCA territory (19 +/- 3) compared to those without EICs (12 +/- 5; p = 0.04). Patients who had major EICs had a larger acute lesion volume in diffusion-weighted imaging (DWI; 140 +/- 78 cm3) compared to those without EICs (33 +/- 51 cm3, p < 0.0001). Regional cerebral blood flow, regional cerebral blood volume, time to peak and mean transit time values were not significantly different in the study groups. CONCLUSION: EICs reflect mainly a larger DWI lesion.

Adult↗
PubMed2004

Early fibrinogen degradation coagulopathy is predictive of parenchymal hematomas in cerebral rt-PA thrombolysis: a study of 157 cases.

BACKGROUND: Little is known about the coagulation factors as predictors of cerebral bleeding in rt-PA thrombolysis. The aim of this study was to determine what early coagulation parameters could predict early hemorrhagic lesions. METHODS: Consecutive patients were included in the Lyon rt-PA protocol. Early hematomas (within 24 hours), diagnosed on an anatomoradiological basis (symptomatic and not symptomatic) were considered for the study. Fibrinogen and fibrin(ogen) degradation products (FDP) were assessed at entry and at 2 and 24 hours after the beginning of thrombolysis. RESULTS: Of 157 patients, 11 had early parenchymal hematomas (7%), 31 had early hemorrhagic infarcts (19.7%), and 115 had no bleeding (73.2%). In logistic regression, FDP at 2 hours was the single predictor of parenchymal hematomas (OR: 2.5; CI: 1.09 to 5.8), whereas an increase of FDP >200 mg/L multiplied the odds of parenchymal hematoma by 4.95 (IC: 1.09 to 22.4). Early parenchymal hematomas were indicative of a poor prognosis at 3 months (P=0.001). CONCLUSIONS: Early parenchymal hematomas appear as both "malignant" and exclusively related to an explosive increase of FDP at 2 hours, ie, an early fibrinogen degradation coagulopathy (EFDC). All patients scheduled to rt-PA thrombolysis should have an assay of FDP 2 hours after the beginning of thrombolysis: patients with an established EFDC (FDP >200 mg/L) should be monitored specifically, with no antithrombotic drug during the first 72 hours. Patients with FDP >100 mg should share the same monitoring.

Cerebral Hemorrhage↗
PubMed2004

Concordance rate differences of 3 noninvasive imaging techniques to measure carotid stenosis in clinical routine practice: results of the CARMEDAS multicenter study.

BACKGROUND AND PURPOSE: To replace digital subtraction angiography (DSA) in carotid stenosis evaluation, noninvasive imaging techniques have to reach a high concordance rate. Our purpose is to compare the concordance rates of contrast-enhanced MR angiography (CEMRA) and CT angiography (CTA) with Doppler ultrasound (DUS) in clinical routine practice. METHODS: We evaluated prospectively with DUS, CEMRA, and CTA 150 patients suspected of carotid stenosis. The overall concordance rates of the 3 techniques were calculated for symptomatic stenosis > or =50% and > or =70%, for asymptomatic stenosis > or =60%, and for occlusion. For the carotid arteries treated by surgery (n=97), the results of each method and combined techniques were recorded, and misclassification rates were evaluated from surgical reports. RESULTS: The overall concordance rates of DUS-CEMRA, DUS-CTA, and CEMRA-CTA were not statistically different. However, the concordance rate of DUS-CEMRA (92.53%) was significantly higher than that for DUS-CTA (79.10%) in the surgical asymptomatic stenosis group (P=0.0258). CTA considered alone would misclassify the stenosis in a significant number of cases (11 of 64) in the surgical asymptomatic group compared with CEMRA (3 of 67) and DUS (1 of 66) (P=0.0186 versus MRA, P=0.0020 versus DUS). CONCLUSIONS: With the techniques as utilized in our study, the overall concordance rates of combined noninvasive methods are similar for measuring carotid stenosis in clinical routine practice, but in asymptomatic carotid stenosis, the decision making for surgery is significantly altered if DUS and CTA are considered in place of DUS and CEMRA.

Aged↗
PubMed2004

Thrombolysis for ischemic stroke in patients with old microbleeds on pretreatment MRI.

BACKGROUND: Old asymptomatic microbleeds (MBs) visualized on T2-weighted MRI are indicative of microangiopathy. They may be a marker of increased risk of intracerebral hemorrhage (ICH) following thrombolysis. However, data regarding this potential risk are limited. METHODS: A retrospective analysis of pretreatment T2-weighted MRI was performed in consecutive stroke patients who received intravenous tissue plasminogen activator (tPA). We aimed to assess the impact of MBs on the risk of cerebral bleeding. The frequency and location of MBs were assessed and compared with the location of ICH after thrombolysis. RESULTS: Forty-four patients were studied. MBs were present on pretreatment MRI in 8 cases (18.2%). At day 1, symptomatic ICH occurred in none of 8 patients with MBs versus 1 of 36 patients without (NS). At day 1, ICH occurred in 3 of 8 patients with MBs versus 10 of 36 patients without (NS). At day 7, symptomatic ICH occurred in 1 of 8 patients with MBs versus 2 of 36 patients without (NS). At day 7, ICH occurred in 5 of 8 patients with MBs versus 12 of 36 patients without (NS). No ICH occurred at the site of an MB. ICH occurred within the ischemic area in all patients who bled. CONCLUSIONS: Our study suggests that stroke patients with a small number of MBs on pretreatment MRI could be treated safely with thrombolysis. Larger prospective studies are needed to address the predictive value of detection of MBs with regard to the risk of tPA-induced ICH.

Acute Disease↗
PubMed2003

Early magnetic resonance imaging prediction of arterial recanalization and late infarct volume in acute carotid artery stroke.

In patients with acute ischemic stroke, early recanalization may save tissue at risk for ischemic infarction, thus resulting in smaller infarcts and better clinical outcome. The hypothesis that clinical and diffusion- and perfusion-weighted imaging (DWI, PWI) parameters may have a predictive value for early recanalization and final infarct size was assessed. Twenty-nine patients were prospectively enrolled and underwent sequential magnetic resonance imaging (1) within 6 hours from hemispheric stroke onset, before thrombolytic therapy; (2) at day 1; and (3) at day 60. Late infarct volume was assessed by T2 -weighted imaging. At each time, clinical status was assessed by the National Institutes of Health Stroke Scale (NIHSS). Twenty-eight patients had arterial occlusion at day 0 magnetic resonance angiography (MRA). They were classified into two groups according to day 1 MRA: recanalization (n = 18) versus persistent occlusion (n = 10). Any significant differences between these groups were assessed regarding (1) PWI and DWI abnormality volumes, (2) relative and absolute time-to-peak (TTP) and apparent diffusion coefficient within the lesion on DWI; and (3) day 60 lesion volume on T2 -weighted imaging. Univariate and multivariate logistic regression analysis showed that the most powerful predictive factors for recanalization were lower baseline NIHSS score and lower baseline absolute TTP within the lesion on DWI. The best predictors of late infarct size were day 0 lesion volume on DWI and day 1 recanalization. Early PWI and DWI studies and day 1 MRA provide relevant predictive information on stroke outcome.

Acute Disease↗
PubMed2003

Hypointense transcerebral veins at T2*-weighted MRI: a marker of hemorrhagic transformation risk in patients treated with intravenous tissue plasminogen activator.

Prediction of hemorrhagic transformation (HT) in patients treated by intravenous recombinant tissue-type plasminogen activator (rt-PA) is a challenging issue in acute stroke management. HT may be correlated with severe hypoperfusion. Signal changes may be observed at susceptibility-weighted magnetic resonance imaging (MRI) within large perfusion defects. A signal drop within cerebral veins at T2*-weighted gradient-echo MRI may be expected in severe ischemia, and may indicate subsequent risk of HT. The authors prospectively searched for an abnormal visibility of transcerebral veins (AVV) within the ischemic area in patients with hemispheric ischemic stroke, before they were treated with intravenous rt-PA therapy. Any correlation between AVV and baseline clinical or MRI findings, or further HT, was noted. An AVV was present in 23 of 49 patients (obvious, n = 8; moderate, n = 15), and was supported by severe hemodynamic changes at baseline MRI. The AVV was correlated with the occurrence of parenchymal hematoma type 2 at computed tomography during the first week (r = 0.44, P = 0.002). Five of six type 2 parenchymal hematomas occurred in association with obvious AVV. At multiple regression analysis, two baseline MRI factors had an independent predictive value for HT risk during the first week: the AVV and the cerebral blood volume ratio (Nagelkerke R2 = 0.48).

Adult↗
PubMed2002

Factors influencing early admission in a French stroke unit.

BACKGROUND AND PURPOSE: Intravenous tissue plasminogen activator improves outcome after ischemic stroke when given within 3 hours of symptoms onset in carefully selected patients. However, only a small proportion of acute stroke patients are currently eligible for thrombolysis, mainly because of excessive delay to hospital presentation. We sought to determine the factors associated with early admission in a French stroke unit. METHODS: We prospectively studied the admission delay of acute stroke patients in a French stroke unit during a 12-month period ending July 1999. Univariate and multivariate regression analyses were performed to evaluate the factors influencing early stroke unit admission and transport by the Emergency Medical Services (EMS) or Fire Department (FD) ambulances. RESULTS: One hundred sixty-six patients were primarily admitted to the stroke unit, with a median admission time of 4 hours 5 minutes. Twenty-nine percent presented within 3 hours of symptoms onset and 75% within 6 hours. Univariate analysis showed that early stroke unit arrival was significantly associated with the following factors: female sex, stroke severity assessed by the National Institutes of Health Stroke Scale score, lowered consciousness, sudden onset of stroke, not living alone, recognition of symptoms by bystanders, and transport by EMS or FD ambulances. Age, ethnicity, level of education, employment status, nocturnal onset, distance from place of stroke to the stroke unit, stroke lesion location, presence of brain hemorrhage, and awareness about the symptoms and risk factors of stroke had no measurable effect on early admission. A multivariate regression model demonstrated that the most significant factors associated with early stroke unit arrival were transport by EMS or FD ambulances and sudden onset of stroke. Female sex and not living alone were also significantly associated with early admission in the multivariate model. Multivariate analysis of the mode of transport showed that transport by EMS or FD ambulances was significantly more frequent among female patients, when stroke symptoms were recognized by bystanders, and when the general practitioner was not the first medical contact. CONCLUSIONS: The present study shows that hospital arrival within the first hours of stroke is feasible in a French stroke unit. As many as 75% of the patients are admitted within the first 6 hours of stroke. This is the first study demonstrating that stroke unit admission in France is fastest in patients brought to the hospital by EMS or FD ambulances. However, only 35% of stroke patients activate the emergency telephone system and are currently transported by EMS or FD ambulances. French stroke patients should be encouraged to seek immediate medical attention by using the emergency telephone system, and stroke management should be reprioritized in the French EMS as a time-dependent medical emergency, with the same level of organization and expertise currently applied to myocardial infarction.

Aged↗