Cardiac arrest - has the time of MRI come?

Three recent articles have shown the potential use of magnetic resonance imaging for the evaluation of comatose survivors of cardiac arrest. While this technique appears promising, significant additional work is required before it can be routinely used in a clinical setting

Utilisation des méthodes avancées d’imagerie dans l’étude des tumeurs cérébrales.

Service de Neuroradiologie, Groupe Hospitalier La Pitié Salpêtrière et Université Pierre et Marie CurieIl est désormais possible d’étudier en routine clinique les tumeurs cérébrales au moyen de méthodes avancées d’IRM. Celles-ci permettent d’orienter le chirurgien vers le type histologique de la tumeur, de préciser son opérabilité et d’évaluer de manière plus fiable l’efficacité des traitements. La spectroscopie et l’IRM de perfusion caractérisent les phénomènes histologiques présents dans la lésion comme la vitesse de multiplication cellulaire, la nécrose, le degré et l’état de la micro vascularisation. Le tenseur de diffusion et l’IRM fonctionnelle aident à préciser la position de la tumeur par rapport aux aires motrices, aux régions du langage et aux voies visuelles, guidant le chirurgien dans son geste opératoire. Dans le suivi thérapeutique, la réponse aux anti angiogéniques peut être étudiée grâce à l’IRM de perfusion, tandis que la spectroscopie peut être utilisée dans le suivi des patients sous chimiothérapie et dans le diagnostic différentiel entre tumeur et radionécrose. Le rôle de l’IRM dans la prise en charge des tumeurs cérébrales est amené à augmenter encore dans le futur, grâce au développement en cours de techniques comme la volumétrie automatisée ou la quantification du 2-hydroxyglutarate en spectroscopie

Clinical review: Prognostic value of magnetic resonance imaging in acute brain injury and coma

Progress in management of critically ill neurological patients has led to improved survival rates. However, severe residual neurological impairment, such as persistent coma, occurs in some survivors. This raises concerns about whether it is ethically appropriate to apply aggressive care routinely, which is also associated with burdensome long-term management costs. Adapting the management approach based on long-term neurological prognosis represents a major challenge to intensive care. Magnetic resonance imaging (MRI) can show brain lesions that are not visible by computed tomography, including early cytotoxic oedema after ischaemic stroke, diffuse axonal injury after traumatic brain injury and cortical laminar necrosis after cardiac arrest. Thus, MRI increases the accuracy of neurological diagnosis in critically ill patients. In addition, there is some evidence that MRI may have potential in terms of predicting outcome. Following a brief description of the sequences used, this review focuses on the prognostic value of MRI in patients with traumatic brain injury, anoxic/hypoxic encephalopathy and stroke. Finally, the roles played by the main anatomical structures involved in arousal and awareness are discussed and avenues for future research suggested

Evolution of structural neuroimaging biomarkers in a series of adult patients with Niemann-Pick type C under treatment

International audienceBackground: Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by a wide clinical spectrum and non-specific conventional magnetic resonance imaging (MRI) signs. As substrate reduction therapy with miglustat is now used in almost all patients, its efficacy and the course of the disease are sometimes difficult to evaluate. Neuroimaging biomarkers could prove useful in this matter. We first performed a retrospective analysis of volumetric and diffusion tensor imaging (DTI) data on 13 adult NPC patients compared to 13 controls of similar age and sex. Eleven NPC patients were then studied using the same neuroimaging modalities over a mean of 5 years. The NPC composite score was used to evaluate disease severity.ResultsNPC patients showed atrophy in basal ganglia – pallidum (p = 0.029), caudate nucleus (p = 0.022), putamen (p = 0.002) and thalamus (p < 0.001) – cerebral peduncles (p = 0.003) and corpus callosum (p = 0.006), compared to controls. NPC patients also displayed decreased fractional anisotropy (FA) in several regions of interest – corona radiata (p = 0.015), internal capsule (p = 0.007), corpus callosum (p = 0.032) and cingulate gyrus (p = 0.002) – as well as a broad increase in radial diffusivity (p < 0.001), compared to controls. Over time, 3 patients worsened clinically, including 2 patients who interrupted treatment, while 8 patients remained stable. With miglustat, no significant volumetric change was observed but FA improved after 2 years in the corpus callosum and the corona radiata of NPC patients (n = 4; p = 0.029) – although that was no longer observed at further time points.ConclusionThis is the first study conducted on a series of adult NPC patients using two neuroimaging modalities and followed under treatment. It confirmed that NPC patients displayed cerebral atrophy in several regions of interest compared to controls. Furthermore, miglustat showed an early effect on diffusion metrics in treated patients. DTI can detect brain microstructure alterations caused by neurometabolic dysfunction. Its potential as a biomarker in NPC shall be further evaluated in upcoming therapeutic trials

Event related potentials elicited by violations of auditory regularities in patients with impaired consciousness.

International audienceImproving our ability to detect conscious processing in non communicating patients remains a major goal of clinical cognitive neurosciences. In this perspective, several functional brain imaging tools are currently under development. Bedside cognitive event-related potentials (ERPs) derived from the EEG signal are a good candidate to explore consciousness in these patients because: (1) they have an optimal time resolution within the millisecond range able to monitor the stream of consciousness, (2) they are fully non-invasive and relatively cheap, (3) they can be recorded continuously on dedicated individual systems to monitor consciousness and to communicate with patients, (4) and they can be used to enrich patients' autonomy through brain-computer interfaces. We recently designed an original auditory rule extraction ERP test that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. Local violations led to an early response in auditory cortex, independent of attention or the presence of a concurrent visual task, while global violations led to a late and spatially distributed response that was only present when subjects were attentive and aware of the violations. In the present work, we report the results of this test in 65 successive recordings obtained at bedside from 49 non-communicating patients affected with various acute or chronic neurological disorders. At the individual level, we confirm the high specificity of the 'global effect': only conscious patients presented this proposed neural signature of conscious processing. Here, we also describe in details the respective neural responses elicited by violations of local and global auditory regularities, and we report two additional ERP effects related to stimuli expectancy and to task learning, and we discuss their relations to consciousness

Automated Analysis of Basal Ganglia Intensity Distribution in Multisequence MRI of the Brain - Application to Creutzfeldt-Jakob Disease

We present a method for the analysis of basal ganglia (including the thalamus) for accurate detection of human spongiform encephalopathy in multisequence MRI of the brain. One common feature of most forms of prion protein infections is the appearance of hyperintensities in the deep grey matter area of the brain in T2-weighted MR images. We employ T1, T2 and Flair-T2 MR sequences for the detection of intensity deviations in the internal nuclei. First, the MR data is registered to a probabilistic atlas and normalised in intensity. Then smoothing is applied with edge enhancement. The segmentation of hyperintensities is performed using a model of the human visual system. For more accurate results, a priori anatomical data from a segmented atlas is employed to refine the registration and remove false positives. The results are robust over the patient data and in accordance to the clinical ground truth. Our method further allows the quantification of intensity distributions in basal ganglia. The caudate nuclei are highlighted as main areas of diagnosis of sporadic Creutzfeldt-Jakob Disease (CJD), in agreement with the histological data. The algorithm permitted to classify the intensities of abnormal signals in sporadic CJD patient FLAIR images with a more significant hypersignal in caudate nuclei (10/10) and putamen (6/10) than in thalami. Using normalised measures of the intensity relations between the internal grey nuclei of patients, we robustly differentiate sporadic CJD and new-variant CJD patients, as a first attempt towards an automatic classification tool of human spongiform encephalopathies

Survival and consciousness recovery are better in the minimally conscious state than in the vegetative state

BACKGROUND The prognosis value of early clinical diagnosis of consciousness impairment is documented by an extremely limited number of studies, whereas it may convey important information to guide medical decisions. OBJECTIVE We aimed at determining if patients diagnosed at an early stage (<90 days after brain injury) as being in the minimally conscious state (MCS) have a better prognosis than patients in the vegetative state/Unresponsive Wakefulness syndrome (VS/UWS), independent of care limitations or withdrawal decisions. METHODS Patients hospitalized in ICUs of the Pitié-Salpêtrière Hospital (Paris, France) from November 2008 to January 2011 were included and evaluated behaviourally with standardized assessment and with the Coma Recovery Scale-Revised as being either in the VS/UWS or in the MCS. They were then prospectively followed until 1July 2011 to evaluate their outcome with the GOSE. We compared survival function and outcomes of these two groups. RESULTS Both survival function and outcomes, including consciousness recovery, were significantly better in the MCS group. This difference of outcome still holds when considering only patients still alive at the end of the study. CONCLUSIONS Early accurate clinical diagnosis of VS/UWS or MCS conveys a strong prognostic value of survival and of consciousness recovery

Quality indicators for patients with traumatic brain injury in European intensive care units

Background: The aim of this study is to validate a previously published consensus-based quality indicator set for the management of patients with traumatic brain injury (TBI) at intensive care units (ICUs) in Europe and to study its potential for quality measur