Yves Samson

Prediction of Malignant Middle Cerebral Artery Infarction by Diffusion-Weighted Imaging

Background and Purpose This study was designed to analyze whether early diffusion-weighted imaging (DWI) provides reliable quantitative information for the prediction of stroke patients at risk of malignant brain infarct. Methods We selected 28 patients with a middle cerebral artery (MCA) infarct and proven MCA or carotid T occlusion on DWI and MRI angiography performed within 14 hours after onset (mean 6.5±3.5 hours, median 5.2 hours). Of these, 10 patients developed malignant MCA infarct, whereas 18 did not. For the 2 groups, we compared the National Institutes of Health Stroke Scale (NIHSS) score at admission, site of arterial occlusion, standardized visual analysis of DWI abnormalities, quantitative volume measurement of DWI abnormalities (volumeDWI), and apparent diffusion coefficient values. Univariate and multivariate discriminant analysis was used to determine the most accurate predictors of malignant MCA infarct. Results Univariate analysis showed that an admission NIHSS score >20, total versus partial MCA infarct, and volumeDWI >145 cm3 were highly significant predictors of malignant infarct. The best predictor was volumeDWI >145 cm3, which achieved 100% sensitivity and 94% specificity. Prediction was further improved by bivariate models combining volumeDWI and apparent diffusion coefficient measurements, which reached 100% sensitivity and specificity in this series of patients. Conclusions Quantitative measurement of infarct volume on DWI is an accurate method for the prediction of malignant MCA infarct in patients with persistent arterial occlusion imaged within 14 hours of onset. This may be of importance for early management of severe stroke patients.

Can diffusion weighted magnetic resonance imaging help differentiate stroke from stroke-like events in MELAS?

The precise mechanism of neurological symptoms in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is still controversial. The diffusion weighted MR findings at the acute phase of a neurological event in MELAS are described and the pathophysiology of stroke-like lesion in the light of diffusion changes is discussed. Brain MRI was performed 2 days after the sudden onset of cortical blindness in a 25 year old patient with MELAS. Fluid attenuated inversion recovery (FLAIR) images showed multifocal cortical and subcortical hyperintensities located bilaterally in the frontobasal and the temporo-occipital lobes. Diffusion weighted images showed normal to increased apparent diffusion coefficient values in the acute left temporooccipital lesion and increased values in the older stroke-like lesions. These diffusion weighted findings support the metabolic rather than the ischaemic pathophysiological hypothesis for stroke-like episodes occurring in MELAS. Normal or increased apparent diffusion coefficient values within 48 hours of a neurological deficit of abrupt onset should raise the possibility of MELAS, especially if conventional MR images show infarct-like lesions.

Differential features of carotid and vertebral artery dissections The CADISP Study

Objective: To examine whether risk factor profile, baseline features, and outcome of cervical artery dissection (CEAD) differ according to the dissection site. Methods: We analyzed 982 consecutive patients with CEAD included in the Cervical Artery Dissection and Ischemic Stroke Patients observational study (n = 619 with internal carotid artery dissection [ICAD], n = 327 with vertebral artery dissection [VAD], n = 36 with ICAD and VAD). Results: Patients with ICAD were older (p < 0.0001), more often men (p = 0.006), more frequently had a recent infection (odds ratio [OR] = 1.59 [95% confidence interval (CI) 1.09–2.31]), and tended to report less often a minor neck trauma in the previous month (OR = 0.75 [0.56–1.007]) compared to patients with VAD. Clinically, patients with ICAD more often presented with headache at admission (OR = 1.36 [1.01–1.84]) but less frequently complained of cervical pain (OR = 0.36 [0.27–0.48]) or had cerebral ischemia (OR = 0.32 [0.21–0.49]) than patients with VAD. Among patients with CEAD who sustained an ischemic stroke, the NIH Stroke Scale (NIHSS) score at admission was higher in patients with ICAD than patients with VAD (OR = 1.17 [1.12–1.22]). Aneurysmal dilatation was more common (OR = 1.80 [1.13–2.87]) and bilateral dissection less frequent (OR = 0.63 [0.42–0.95]) in patients with ICAD. Multiple concomitant dissections tended to cluster on the same artery type rather than involving both a vertebral and carotid artery. Patients with ICAD had a less favorable 3-month functional outcome (modified Rankin Scale score >2, OR = 3.99 [2.32–6.88]), but this was no longer significant after adjusting for baseline NIHSS score. Conclusion: In the largest published series of patients with CEAD, we observed significant differences between VAD and ICAD in terms of risk factors, baseline features, and functional outcome.

The underlying pathophysiology of ictal dystonia in temporal lobe epilepsy An FDG-PET study

Background: Unilateral dystonic posturing of limbs occurs frequently in medial temporal lobe epilepsy (MTLE) but its underlying anatomic basis is still unknown. Objective: To investigate the pathophysiology of dystonic posturing, we examined the relation between the occurrence of dystonia and interictal cerebral metabolic abnormalities using fluorodeoxyglucose (FDG)-PET in MTLE patients. Methods: Video recordings of 30 patients with documented MTLE were reviewed to assess the presence of ictal dystonic posturing. Interictal FDG-PET was performed in all patients. Results: Eighteen patients exhibited dystonic posturing-contralateral to the seizure focus in 16 cases, bilateral in one, and ipsilateral in one. Dystonia was statistically associated with more severe hypometabolism in the striatal and in the orbitofrontal regions ipsilateral to the seizure focus. Conclusion: Hypometabolism observed in the striatal region of patients with ictal dystonic posturing suggests that the basal ganglia are involved in the generation of ictal dystonic posturing in MTLE.

Diffusion-Weighted Magnetic Resonance Imaging in a Case of Cerebral Venous Thrombosis

BACKGROUND Diffusion-weighted imaging (DWI) is the most sensitive MR sequence in acute arterial ischemic stroke but has not yet been evaluated in venous cerebral ischemia. We describe a patient with DWI performed at the acute phase of a venous ischemic stroke. CASE DESCRIPTION A rapid cerebral MRI including DWI and fast fluid-attenuated inversion recovery (FLAIR) sequences was performed at the acute phase of a venous stroke confirmed by conventional angiography. DWI showed a slight decrease in apparent diffusion coefficient values 3 hours after onset (0.53+/-0.07x10(-3) mm2/s) and was normal 48 hours later (0.064+/-0.15x10(-3) mm2/s). Fast FLAIR sequences showed large left frontoparietal hyperintensities. The lack of a clear decrease in apparent diffusion coefficient values associated with marked FLAIR abnormalities may suggest prominent or early associated vasogenic edema. Physiopathological differences between arterial and venous ischemia may explain the different type of DWI FLAIR abnormalities during the acute phase as well as the better recovery of neurological deficit in venous stroke than in arterial ischemic stroke. CONCLUSIONS In the context of an acute stroke, the contrast between marked FLAIR and subtle DWI abnormalities on MRI may reflect the venous mechanism of cerebral ischemia.

Common variation in PHACTR1 is associated with susceptibility to cervical artery dissection

Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year). Minor cervical traumas, infection, migraine and hypertension are putative risk factors, and inverse associations with obesity and hypercholesterolemia are described. No confirmed genetic susceptibility factors have been identified using candidate gene approaches. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69–0.82; P = 4.46 × 10−10), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10−3; combined P = 1.00 × 10−11). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions.

Cervical artery dissection: trauma and other potential mechanical trigger events.

Objective: To examine the import of prior cervical trauma (PCT) in patients with cervical artery dissection (CeAD). Methods: In this observational study, the presence of and the type of PCT were systematically ascertained in CeAD patients using 2 different populations for comparisons: 1) age- and sex-matched patients with ischemic stroke attributable to a cause other than CeAD (non–CeAD-IS), and 2) healthy subjects participating in the Cervical Artery Dissection and Ischemic Stroke Patients Study. The presence of PCT within 1 month was assessed using a standardized questionnaire. Crude odds ratios (ORs) with 95% confidence intervals (CIs) and ORs adjusted for age, sex, and center were calculated. Results: We analyzed 1,897 participants (n = 966 with CeAD, n = 651 with non–CeAD-IS, n = 280 healthy subjects). CeAD patients had PCT in 40.5% (38.2%–44.5%) of cases, with 88% (344 of 392) classified as mild. PCT was more common in CeAD patients than in non–CeAD-IS patients (ORcrude 5.6 [95% CI 4.20–7.37], p < 0.001; ORadjusted 7.6 [95% CI 5.60–10.20], p < 0.001) or healthy subjects (ORcrude 2.8 [95% CI 2.03–3.68], p < 0.001; ORadjusted 3.7 [95% CI 2.40–5.56], p < 0.001). CeAD patients with PCT were younger and presented more often with neck pain and less often with stroke than CeAD patients without PCT. PCT was not associated with functional 3-month outcome after adjustment for age, sex, and stroke severity. Conclusion: PCT seems to be an important environmental determinant of CeAD, but was not an independent outcome predictor. Because of the characteristics of most PCTs, the term mechanical trigger event rather than trauma may be more appropriate.

Association of Vascular Risk Factors With Cervical Artery Dissection and Ischemic Stroke in Young Adults

Background— Little is known about the risk factors for cervical artery dissection (CEAD), a major cause of ischemic stroke (IS) in young adults. Hypertension, diabetes mellitus, smoking, hypercholesterolemia, and obesity are important risk factors for IS. However, their specific role in CEAD is poorly investigated. Our aim was to compare the prevalence of vascular risk factors in CEAD patients versus referents and patients who suffered an IS of a cause other than CEAD (non-CEAD IS) in the multicenter Cervical Artery Dissection and Ischemic Stroke Patients (CADISP) study. Methods and Results— The study sample comprised 690 CEAD patients (mean age, 44.2±9.9 years; 43.9% women), 556 patients with a non-CEAD IS (44.7±10.5 years; 39.9% women), and 1170 referents (45.9±8.1 years; 44.1% women). We compared the prevalence of hypertension, diabetes mellitus, hypercholesterolemia, smoking, and obesity (body mass index ≥30 kg/m2) or overweightness (body mass index ≥25 kg/m2 and <30 kg/m2) between the 3 groups using a multinomial logistic regression adjusted for country of inclusion, age, and gender. Compared with referents, CEAD patients had a lower prevalence of hypercholesterolemia (odds ratio 0.55; 95% confidence interval, 0.42 to 0.71; P<0.0001), obesity (odds ratio 0.37; 95% confidence interval, 0.26 to 0.52; P<0.0001), and overweightness (odds ratio 0.70; 95% confidence interval, 0.57 to 0.88; P=0.002) but were more frequently hypertensive (odds ratio 1.67; 95% confidence interval, 1.32 to 2.1; P<0.0001). All vascular risk factors were less frequent in CEAD patients compared with young patients with a non-CEAD IS. The latter were more frequently hypertensive, diabetic, and current smokers compared with referents. Conclusion— These results, from the largest series to date, suggest that hypertension, although less prevalent than in patients with a non-CEAD IS, could be a risk factor of CEAD, whereas hypercholesterolemia, obesity, and overweightness are inversely associated with CEAD.

Inflammation et accident ischémique cérébral aigu. Données actuelles et perspectives

Resume Introduction La reaction inflammatoire joue un role important dans l’accident ischemique cerebral (AIC). De nombreuses etudes experimentales et cliniques soulignent les effets deleteres, mais parfois aussi benefiques de l’inflammation. Nous decrirons les principaux aspects de cette reponse inflammatoire, ainsi que leurs applications therapeutiques. Etat des connaissances/perspectives Les resultats des etudes descriptives et therapeutiques des marqueurs somatiques a la phase aigue de l’AIC (proteine C-reactive et temperature) sont heterogenes. Les principales cibles etudiees sont les molecules d’adhesion cellulaire — CAM (integrines, selectines et la superfamille des immunoglobulines), la reponse leucocytaire et cytokinique, la microglie et la barriere hemato-encephalique. Les arguments experimentaux, suffisamment nombreux, en particulier sur le caractere deletere de l’adhesion leucocytaire, ont permis d’entreprendre des essais cliniques. Ces etudes, utilisant des molecules anti-inflammatoires (anti-adhesion leucocytaire, antipyretique), ont toutes ete negatives, peut-etre parce que la cinetique de reaction inflammatoire n’est pas suffisamment prise en compte. Des travaux recents suggerent que l’insuline et les statines pourraient modifier la reaction inflammatoire a la phase aigue de l’AIC. Conclusion L’inflammation est aujourd’hui un des axes majeurs de la recherche therapeutique sur la progression de l’infarctus au cours des premieres heures de l’AIC. La comprehension de la physiopathologie de la reponse inflammatoire et de sa cinetique, devra permettre d’ameliorer le protocole des etudes cliniques futures.

Thrombolysis in Cervical Artery Dissection - Data from the Cervical Artery Dissection and Ischaemic Stroke Patients (CADISP) database

Objective:  To examine whether thrombolysis for stroke attributable to cervical artery dissection (CeADStroke) affects outcome and major haemorrhage rates.