In vivo MRI assessment of permanent middle cerebral artery occlusion by electrocoagulation: pitfalls of procedure

Permanent middle cerebral artery (MCA) occlusion (pMCAO) by electrocoagulation is a commonly used model but with potential traumatic lesions. Early MRI monitoring may assess pMCAO for non-specific brain damage. The surgical steps of pMCAO were evaluated for traumatic cerebral injury in 22 Swiss mice using diffusion and T2-weighted MRI (7T) performed within 1 h and 24 h after surgery. Temporal muscle cauterization without MCA occlusion produced an early T2 hyperintensity mimicking an infarct. No lesion was visible after temporal muscle incision or craniotomy. Early MRI monitoring is useful to identify non-specific brain injury that could hamper neuroprotective drugs assessment

Impact of the Thrombectomy Trials on the Management and Outcome of Large Vessel Stroke: Data From the Lyon Stroke Center

Introduction: Randomized trials (RT) have recently validated the superiority of thrombectomy over standard medical care, including intravenous thrombolysis (IVT). However, data on their impact on routine clinical care remains scarce.Methods: Using a prospective observational registry, we assessed: (1) the clinical and radiological characteristics of all consecutive patients treated with thrombectomy; (2) the outcome of all patients with M1 occlusion (treated with thrombectomy or IVT alone). Two periods were compared: before (2013–2014) and after (2015–2016) the publication of RT.Results: Endovascular procedures significantly increased between the two periods (N = 82 vs. 314, p < 0.0001). In 2015–2016, patients were older (median [IQR]: 69 [57-80]; vs. 66 [53-74]; p = 0.008), had shorter door-to-clot times (69 [47-95]; vs. 110 [83-155]; p < 0.0001) resulting in a trend toward shorter delay from symptom onset to reperfusion (232 [185-300]; vs. 250 [200-339]; p = 0.1), with higher rates of reperfusion (71 vs. 48%; p = 0.0001). Conversely, no significant differences in baseline NIHSS scores, ASPECTS, delay to IVT or intracranial hemorrhage were found. In 2015–2016, patients with M1 occlusion were treated with thrombectomy more often than in 2013–2014 (87 vs. 32%, respectively; p < 0.0001), with a significant improvement in clinical outcome (shift analysis, lower modified Rankin scale scores: OR = 1.68; 95% CI: 1.10–2.57; p = 0.017).Conclusion: Following the publication of RT, thrombectomy was rapidly implemented with significant improvements in intrahospital delay and reperfusion rates. Treatment with thrombectomy increased with better clinical outcomes in patients with M1 occlusion

Physiopathologie et imagerie de l’AVC à la phase précoce

National audienceLes accidents vasculaires cérébraux (AVC) constituent la 3ème cause de mortalité et l’une des principales causes d’invalidité. Les AVC comprennent les accidents ischémiques (80 %) et les accidents hémorragiques. Dans l'immense majorité des cas, l'accident ischémique résulte de l'occlusion d'une artère cérébrale. La gravité des lésions cérébrales dépend de la durée de l'occlusion et des possibilités de suppléance à partir des artères cérébrales adjacentes. L’ischémie cérébrale survient lorsque la perfusion cérébrale chute au-dessous d’un certain seuil. Les systèmes de protection vis à vis d’une telle chute sont :- vasculaire : l’autorégulation cérébrale permet un maintien du débit sanguin cérébral par dilatation des artérioles cérébrales- puis métabolique : lorsque la vasodilatation ne peut plus compenser la baisse de la perfusion cérébrale, le débit sanguin cérébral diminue mais la consommation d'oxygène est maintenue grâce à l'augmentation du taux d'extraction d'oxygène. Lorsque ce dernier mécanisme est dépassé, le métabolisme et la fonction cellulaires sont perturbés. La profondeur et la durée de ces perturbations conditionnent leurs conséquences. L’arrêt des pompes membranaires entraîne un transfert de sodium - et de l’eau qui lui est osmotiquement liée - du secteur extracellulaire dans la cellule. C’est l’oedème cytotoxique. Celui-ci est bien mis en évidence par l’IRM de diffusion, sensible aux mouvements libres de l’eau. L’hypoperfusion est moins sévère dans les parties plus périphériques de l’aire ischémique grâce aux suppléances collatérales et, si les neurones ne sont plus fonctionnels faute de substrat énergétique, leur atteinte est potentiellement réversible pendant plusieurs heures (pénombre ischémique) . Ces notions justifient les traitements de reperfusion (thrombolyse ou thrombectomie) dans certains AVC

Isolated atlas-duplication as a manifestation of persistent proatlas: a case report

International audienc

Spontaneous multiple cervical artery dissections after alemtuzumab

International audienceWe report a case of multiple cervical artery dissections that occurred 4 days after a first course of alemtuzumab in a woman with relapsing–remitting multiple sclerosis and discuss its potential relationship and mechanisms of action. In particular, an arterial inflammatory process, secondary to cytokine release, could potentially lead to intimal thickening, luminal irregularities, stenosis, and ultimately occlusion. Occurrence of an unexpected serious adverse event, in our case, multiple cervical artery dissections, especially in a close time window after drug administration, questions a potential causal relationship with the drug or a simple coincidence

Diffusion tensor imaging abnormalities of the trigeminal nerve root in patients with classical trigeminal neuralgia: a pre- and postoperative comparative study 4 years after microvascular decompression

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Imagerie des pathologies non traumatiques du cordon médullaire et des espaces périmédullaires

International audienc

On the Influence of Normalization Strategies for Perfusion MRI in Acute Stroke

International audienceNormalization of magnetic resonance images with a given reference is a common preprocessing task which is rarely discussed. We review and address this question for a specific neuro-imaging problem of practical huge interest. We investigate the influence of the location of region of interest used for normalization of perfusion maps obtained with perfusion magnetic resonance imaging in the framework of the study of acute stroke. We demonstrate that a slice by slice normalization based on the whole hemisphere strategy optimally reduces the variability of the predictive value of the different perfusion maps. Interestingly, this is obtained for all the tested perfusion maps both from numerical simulation of perfusion MRI and from perfusion maps of real patients through a Neyman-Pearson detection strategy. These are important results to ease the quantitative assessment of stroke lesion from perfusion MRI on cohorts of patients. The proposed methodology could easily be transposed to other medical imaging problems where normalization of images is necessary

A NOVEL AUTOENCODERS-LSTM MODEL FOR STROKE OUTCOME PREDICTION USING MULTIMODAL MRI DATA

International audiencePatient outcome prediction is critical in management of ischemic stroke. In this paper, a novel machine learning model is proposed for stroke outcome prediction using multimodal Magnetic Resonance Imaging (MRI). The proposed model consists of two serial levels of Autoencoders (AEs), where different AEs at level 1 are used for learning unimodal features from different MRI modalities and a AE at level 2 is used to combine the unimodal features into compressed multimodal features. The sequences of multimodal features of a given patient are then used by an LSTM network for predicting outcome score. The proposed AE 2-LSTM model is proved to be an effective approach for better addressing the multimodality and volumetric nature of MRI data. Experimental results show that the proposed AE 2-LSTM outperforms the existing state-of-the art models by achieving highest AUC=0.71 and lowest MAE=0.34