High-density electric source imaging (esi) in focal epilepsy: a prospective study of 150 operated patients

Purpose: EEG is mandatory in the diagnosis of the epilepsy syndrome. However, its potential as imaging tool is still under estimated. In the present study, we aim to determine the prerequisites of maximal benefit of electric source imaging (ESI) to localize the irritative zone in patients with focal epilepsy. Methods: One hundred fifty patients suffering from focal epilepsy and with minimum 1 year postoperative follow-up were studied prospectively and blinded to the underlying diagnosis. We evaluated the influence of two important factors on sensitivity and specificity of ESI: the number of electrodes (low resolution, LR-ESI: <30 versus high resolution, HR-ESI: 128-256 electrodes), and the use of individual MRI (i-MRI) versus template MRI (t-MRI) as the head model. Findings: ESI had a sensitivity of 85% and a specificity of 87% when HR-ESI with i-MRI was used. Using LR-ESI, sensitivity decreased to 68%, or even 57% when only t-MRI was available. The sensitivity of HR-ESI/i-MRI compared favorably with those of MRI (76%), PET (69%) and ictal/interictal SPECT (64%). Interpretation: This study on a large patient group shows excellent sensitivity and specificity of ESI if 128 EEG channels or more are used for ESI and if the results are coregistered to the patient's individual MRI. Localization precision is as high as or even higher than established brain imagery techniques. HR-ESI appears to be a valuable additional imaging tool, given that larger electrode arrays are easily and rapidly applied with modern EEG equipment and that structural MRI is nearly always available for these patients.

Patterns of recovery following focal hemispheric lesions : relationship between lasting deficit and damage to specialized networks

Rapport de synthèse : Objectif : Les déficits cognitifs présents dans la phase aiguë d'une lésion hémisphérique focale ont tendance à être de nature plus importante et plus générale que les déficits résiduels qui persistent dans la phase chronique de récupération. Nous avons investigué, dans le cadre de ce travail, les modèles de récupération auditive et la relation qui se dessine entre les déficits et les dommages relatifs à des réseaux spécifiques, pris comme modèle cognitif des fonctions auditives. De nombreuses études humaines dans les domaines de la neuropsychologie, de la psychophysique ainsi que des études d'activation suggèrent que les processus de reconnaissance et de localisation sonores sont effectués par l'intermédiaire de réseaux distincts tant sur le plan anatomique que fonctionnel : il s'agit des zones de traitement du «What» et du «Where », qui sont toutes deux présentes dans les deux hémisphères. Des études ont démontré que des lésions hémisphériques focales gauches ou droites, centrées sur ces réseaux, sont associées dans la phase chronique de récupération à des déficits correspondant en ce qui concerne la reconnaissance et/ou la localisation sonore. Méthode : Dans le cadre de ce travail, nous avons analysé les résultats concernant les performances auditives chez 24 patients ayant subi des lésions hémisphériques focales avec déficits secondaires dans des tâches de reconnaissance, de localisation et/ou de perception du mouvement sonore lors d'un premier testing effectué en phase aiguë (9 patients), en phase subaiguë (6 patients) ou en phase chronique précoce (9 patients). La totalité de ces patients ont bénéficié d'un second testing en phase chronique. Les observations effectuées ont servi à l'élaboration de patterns de récupération auditive. Résultats : Tous les 24 patients avaient initialement un déficit dans le domaine de la localisation et/ou de la perception du mouvement sonore. Dans la phase aiguë, ce déficit survenait sans atteinte spécifique du réseau «Where » chez presque la moitié des patients ; en revanche, cette situation n'était jamais observée chez les patients testés en phase chronique précoce. Une absence de récupération avait tendance à être associée à un dommage spécifique au réseau concerné ainsi qu'à la persistance d'un déficit au-delà de la phase aiguë. Les déficits résiduels n'étaient par ailleurs pas strictement en lien avec la taille lésionnelle ou l'étendue de l'atteinte du réseau spécifique. Conclusion : Nos résultats suggèrent que des mécanismes distincts sous-tendent la récupération et la plasticité à différentes périodes temporelles post-lésionnelles.

Reversible acquired epileptic frontal syndrome and CSWS suppression in a child with congenital hemiparesis treated by hemispherotomy

Rapport de synthèse : Cette thèse a étudié en détail le cas d'un enfant souffrant d'une hémiplégie congénitale sur un infarctus prénatal étendu qui a développé une forme particulière d'épilepsie, le syndrome des pointes ondes continues du sommeil (POCS), associé à une régression mentale massive. Les caractéristiques de cette détérioration pointaient vers un dysfonctionnement de type frontal. Une chirurgie de l'épilepsie (hémisphérotomie) a, non seulement, permis la guérison de l'épilepsie mais une récupération rapide sur le plan comportemental et cognitif, suivie d'une reprise plus lente du développement, avec finalement à l'âge de 11 ans un niveau de déficience intellectuelle modérée. L'intérêt de cette étude réside dans le fait que l'enfant a pu être suivi prospectivement entre l'âge de 4.5 ans et 11 ans par des enregistrements électro-encéphalographiques (EEG) ainsi que des tests neuropsychologiques et des questionnaires de comportements sériés, permettant de comparer les périodes pré-, péri- et postopératoires, ce qui est rarement réalisable. Un enregistrement EEG de surface a même pu être effectué durant l'opération sur l'hémisphère non lésé, permettant de documenter l'arrêt des décharges épileptiformes généralisées dès la fin de l'intervention. L'hypothèse que nous avons- souhaité démontrer est que la régression comportementale et cognitive présentée par l'enfant après une période de développement précoce presque normale (retard de langage) était de nature épileptique : nous l'expliquons par la propagation de l'activité électrique anormale à partir de la lésion de l'hémisphère gauche vers les régions préservées, en particulier frontales bilatérales. L'hémisphérotomie a permis une récupération rapide en déconnectant l'hémisphère gauche lésé et épileptogène de l'hémisphère sain, qui a ainsi pu reprendre les fonctions cognitives les plus importantes. Les progrès plus lents par la suite et l'absence de rattrapage au delà d'un niveau de déficience mentale modérée sont plus difficiles à expliquer: on postule ici un effet de l'épilepsie sur le développement de réseaux neuronaux de l'hémisphère initialement non lésé, réseaux qui sont à la fois à un stade précoce de leur maturation et en cours de réorganisation suite à la lésion prénatale. La littérature sur les déficits cognitifs avant et après hemisphérotomie s'est surtout préoccupée du langage et de sa récupération possible. À notre connaissance, notre étude est la première à documenter la réversibilité d'une détérioration mentale avec les caractéristiques d'un syndrome frontal après hémisphérotomie. La chirurgie de l'épilepsie a offert ici une occasion unique de documenter le rôle de l'activité épileptique dans la régression cognitive puisqu'en interrompant brusquement la propagation de l'activité électrique anormale, on a pu comparer la dynamique du développement avant et après l'intervention. La mise en relation des multiples examens cliniques et EEG pratiqués chez un seul enfant sur plusieurs années a permis d'obtenir des informations importantes dans la compréhension des troubles cognitifs et du comportement associés aux épilepsies focales réfractaires. ABSTRACT : A boy with a right congenital hemiparesis due to a left pre-natal middle cerebral artery infarct developed focal epilepsy at 33 months and then an insidious and subsequently more rapid, massive cognitive and behavioural regression with a frontal syndrome between the ages of 4 and 5 years with continuous spike-waves during sleep (CSWS) on the EEG. Both the epilepsy and the CSWS were immediately suppressed by hemispherotomy at the age of 5 years and 4months. A behavioural-cognitive follow-up prior to hemispheratomy, an per-operative EEG and corticography and serial post-operative neuropsychological assessments were performed until the age of 11 years. The spread of the epileptic activity to the "healthy" frontal region was the cause of the reversible frontal syndrome. A later gradual long-term but incomplete cognitive recovery, with moderate mental disability was documented. T9ris outcome is probably explained by another facet of the epilepsy, namely the structural effects of prolonged epileptic dischazges in rapidly developing cerebral networks which are, at the same time undergoing the reorganization imposed by a unilateral early hemispheric lesion. Group studies on the outcome of children before and after hemispherectomy using only single IQ measures, pre- and postoperatively, may miss particular epileptic cognitive dysfunctions as they are likely to be different from case to case. Such detailed and rarely available complementary clinical and EEG data obtained in a single case at different time periods in relation to the epilepsy, including peroperative electrophysiological findings, may help to understand the different cognitive deficits and recovery profiles and the limits of full cognitive recovery.

Brain damage in methylmalonic aciduria: 2-methylcitrate induces cerebral ammonium accumulation and apoptosis in 3D organotypic brain cell cultures.

BACKGROUND: Methylmalonic aciduria is an inborn error of metabolism characterized by accumulation of methylmalonate (MMA), propionate and 2-methylcitrate (2-MCA) in body fluids. Early diagnosis and current treatment strategies aimed at limiting the production of these metabolites are only partially effective in preventing neurological damage. METHODS: To explore the metabolic consequences of methylmalonic aciduria on the brain, we used 3D organotypic brain cell cultures from rat embryos. We challenged the cultures at two different developmental stages with 1 mM MMA, propionate or 2-MCA applied 6 times every 12 h. In a dose-response experiment cultures were challenged with 0.01, 0.1, 0.33 and 1 mM 2-MCA. Immunohistochemical staining for different brain cell markers were used to assess cell viability, morphology and differentiation. Significant changes were validated by western blot analysis. Biochemical markers were analyzed in culture media. Apoptosis was studied by immunofluorescence staining and western blots for activated caspase-3. RESULTS: Among the three metabolites tested, 2-MCA consistently produced the most pronounced effects. Exposure to 2-MCA caused morphological changes in neuronal and glial cells already at 0.01 mM. At the biochemical level the most striking result was a significant ammonium increase in culture media with a concomitant glutamine decrease. Dose-response studies showed significant and parallel changes of ammonium and glutamine starting from 0.1 mM 2-MCA. An increased apoptosis rate was observed by activation of caspase-3 after exposure to at least 0.1 mM 2-MCA. CONCLUSION: Surprisingly, 2-MCA, and not MMA, seems to be the most toxic metabolite in our in vitro model leading to delayed axonal growth, apoptosis of glial cells and to unexpected ammonium increase. Morphological changes were already observed at 2-MCA concentrations as low as 0.01 mM. Increased apoptosis and ammonium accumulation started at 0.1 mM thus suggesting that ammonium accumulation is secondary to cell suffering and/or cell death. Local accumulation of ammonium in CNS, that may remain undetected in plasma and urine, may therefore play a key role in the neuropathogenesis of methylmalonic aciduria both during acute decompensations and in chronic phases. If confirmed in vivo, this finding might shift the current paradigm and result in novel therapeutic strategies.

Intratracheal suctioning in sick preterm infants: prevention of intracranial hypertension and cerebral hypoperfusion by muscle paralysis.

In a prospective nonrandomized study, using each baby as his or her own control, we compared intracranial pressure (anterior fontanel pressure as measured with the Digilab pneumotonometer), cerebral perfusion pressure, BP, heart rate, transcutaneous Po2, and transcutaneous Pco2 before, during, and after endotracheal suctioning, with and without muscle paralysis, in 28 critically ill preterm infants with respiratory distress syndrome. With suctioning, there was a small but significant increase in intracranial pressure in paralyzed patients (from 13.7 [mean] +/- 4.4 mm Hg [SD] to 15.8 +/- 5.2 mm Hg) but a significantly larger (P less than .001) increase when they were not paralyzed (from 12.5 +/- 3.6 to 28.5 +/- 8.3 mm Hg). Suctioning led to a slight increase in BP with (from 45.3 +/- 9.1 to 48.0 +/- 8.7 mm Hg) and without muscle paralysis (from 45.1 +/- 9.4 to 50.0 +/- 11.7 mm Hg); but there was no significant difference between the two groups. The cerebral perfusion pressure in paralyzed infants did not show any significant change before, during, and after suctioning (31.5 +/- 9.1 mm Hg before v 32.0 +/- 8.7 mm Hg during suctioning), but without muscle paralysis cerebral perfusion pressure decreased (P less than .001) from 32.8 +/- 9.7 to 21.3 +/- 13.1 mm Hg. Suctioning induced a slight decrease in mean heart rate and transcutaneous Po2, but pancuronium did not alter these changes. There was no statistical difference in transcutaneous Pco2 before, during, and after suctioning with and without muscle paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral perfusion pressure and risk of brain hypoxia in severe head injury: a prospective observational study

INTRODUCTION Higher and lower cerebral perfusion pressure (CPP) thresholds have been proposed to improve brain tissue oxygen pressure (PtiO2) and outcome. We study the distribution of hypoxic PtiO2 samples at different CPP thresholds, using prospective multimodality monitoring in patients with severe traumatic brain injury. METHODS This is a prospective observational study of 22 severely head injured patients admitted to a neurosurgical critical care unit from whom multimodality data was collected during standard management directed at improving intracranial pressure, CPP and PtiO2. Local PtiO2 was continuously measured in uninjured areas and snapshot samples were collected hourly and analyzed in relation to simultaneous CPP. Other variables that influence tissue oxygen availability, mainly arterial oxygen saturation, end tidal carbon dioxide, body temperature and effective hemoglobin, were also monitored to keep them stable in order to avoid non-ischemic hypoxia. RESULTS Our main results indicate that half of PtiO2 samples were at risk of hypoxia (defined by a PtiO2 equal to or less than 15 mmHg) when CPP was below 60 mmHg, and that this percentage decreased to 25% and 10% when CPP was between 60 and 70 mmHg and above 70 mmHg, respectively (p < 0.01). CONCLUSION Our study indicates that the risk of brain tissue hypoxia in severely head injured patients could be really high when CPP is below the normally recommended threshold of 60 mmHg, is still elevated when CPP is slightly over it, but decreases at CPP values above it.

Synthesis and transport of creatine in the CNS: importance for cerebral functions.

J. Neurochem. (2010) 10.1111/j.1471-4159.2010.06935.x Abstract Apart of its well known function of 'energetic buffer' through the creatine/phosphocreatine/creatine kinase system allowing the regeneration of ATP, creatine has been recently suggested as a potential neuromodulator of even true neurotransmitter. Moreover, the recent discovery of primary creatine deficiency syndromes, due to deficiencies in l-arginine : glycine amidinotransferase or guanidinoacetate methyltransferase (the two enzymes allowing creatine synthesis) or in the creatine transporter, has shed new light on creatine synthesis, metabolism and transport, in particular in CNS which appears as the main tissue affected by these creatine deficiencies. Recent data suggest that creatine can cross blood-brain barrier but only with a poor efficiency, and that the brain must ensure parts of its needs in creatine by its own endogenous synthesis. Finally, the recent years have demonstrated the interest to use creatine as a neuroprotective agent in a growing number of neurodegenerative diseases, including Parkinson's and Huntington's diseases. This article aims at reviewing the latest data on creatine metabolism and transport in the brain, in relation to creatine deficiencies and to the potential use of creatine as neuroprotective molecule. Emphasis is also given to the importance of creatine for cerebral function.

Cerebral perfusion in sepsis.

This article is one of ten reviews selected from the Yearbook of Intensive Care and Emergency Medicine 2010 (Springer Verlag) and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/yearbook. Further information about the Yearbook of Intensive Care and Emergency Medicine is available from http://www.springer.com/series/2855.

Atypical Vascular Involvement in a Case of Behçet's Disease.

Introduction. Behçet's disease (BD) is a form of vasculitis of unknown etiology which is rare in our environment. It is characterized by a variety of clinical manifestations and usually affects young adults. Recurrent oral and genital ulcers are a characteristic and extremely frequent symptom, but mortality is linked with more significant symptoms such as aortic pseudoaneurysm, pulmonary pseudoaneurysm, and cerebral venous thrombosis. Patient and Method. We present a case of a young male with atypical BD and severe polyvascular involvement (previous cerebral venous thrombosis and current peripheral venous thrombosis, acute ischemia, and peripheral arterial pseudoaneurysm) who required urgent surgical intervention due to a symptomatic external iliac pseudoaneurysm. Result. The pseudoaneurysm was successfully treated, we performed an iliofemoral bypass, and we treated it with steroids and immunosuppressive therapy. Conclusions. These rare clinical manifestations highlight the importance of considering BD in young patients, even in usual cases of vascular intervention, whether arterial or venous in nature.

Microdiàlisis cerebral aplicada a l'estudi del metabolisme energètic i a la resposta neuroinflamatòria dels pacients amb traumatisme cranioencefàlic

La tècnica de la microdiàlisis cerebral (MDC) és un instrument que proporciona informació rellevant en la monitorització del metabolisme cerebral en els pacients neurocrítics. El lactat i l’índex lactat-piruvat (ILP) són dos marcadors utilitzats per a la detecció de la hipòxia cerebral en pacients que han patit un traumatisme cranioencefàlic (TCE). Aquests dos marcadors poden estar anormalment elevats en circumstàncies que no cursen amb hipòxia tissular. Per una altra banda la recent aparició dels catèters de MDC amb porus de major mida denominats d’”alta resolució”, permet ampliar el rang de molècules que es poden detectar en el dialitzat. Objectius: 1) descriure les característiques del metabolisme energètic cerebral que s’observa en la fase aguda dels pacients que han patit un TCE en base als dos indicadors del metabolisme anaeròbic: lactat i ILP, i 2) determinar la recuperació relativa (RR) de les molècules implicades en la resposta neuroinflamatòria: de IL-1β, IL- 6, IL-8 i IL-10. Material i mètodes: Es van seleccionar 46 pacients d’una cohort de pacients amb TCE moderat o greu ingressats a la Unitat de Cures Intensives de l’Hospital Universitari de la Vall d’Hebron i monitoritzats amb MDC. Es van analitzar els nivells de lactat i ILP i es va correlacionar amb els nivells de PtiO2. Es van realitzar experiments in vitro per estudiar la recuperació de les membranes de 100 KDa per tal de poder interpretar posteriorment els nivells reals de les molècules estudiades en l’espai extracel•lular del teixit cerebral. Resultats: La concordança entre el lactat i l’índex LP per a determinar episodis de disfunció metabòlica va ser dèbil (índex de kappa = 0,36, IC 95%: 0,34-0,39). Més del 80% dels casos en què el lactat i l’índex LP es trobaven incrementats, els valors de la PtiO2 es van trobar dins els rangs de normalitat (PtiO2&15mmHg). La recuperació de les citoquines a través de la membrana de microdiàlisis va ser menor de l’esperat tenint en compte la mida dels porus de la membrana. Conclusions: el lactat i l’índex LP elevats va ser una troballa freqüent després d’un TCE i no es va relacionar, en la majoria de casos, amb episodis d’hipòxia tissular. Per un altra part la mida del porus de la membrana no és l’únic paràmetre indicador de la RR de macromolècules.

Lésions cérébrales du prématuré et techniques d'imagerie à visée pronostique du développement neurocognitif [Cerebral brain injury in preterm infants and the role of neuroimaging in predicting neurodevelopmental outcomes].

Due to advances in neonatal intensive care over the last decades, the pattern of brain injury seen in very preterm infants has evolved in more subtle lesions that are still essential to diagnose in regard to neurodevelopmental outcome. While cranial ultrasound is still used at the bedside, magnetic resonance imaging (MRI) is becoming increasingly used in this population for the assessment of brain maturation and white and grey matter lesions. Therefore, MRI provides a better prognostic value for the neurodevelopmental outcome of these preterms. Furthermore, the development of new MRI techniques, such as diffusion tensor imaging, resting state functional connectivity and magnetic resonance spectroscopy, may further increase the prognostic value, helping to counsel parents and allocate early intervention services.

Preconditioning with Triiodothyronine Improves the Clinical Signs and Acute Tubular Necrosis Induced by Ischemia/Reperfusion in Rats.

BACKGROUND Renal ischemia/reperfusion (I/R) injury is manifested by acute renal failure (ARF) and acute tubular necrosis (ATN). The aim of this study was to evaluate the effectiveness of preconditioning with 3, 3, 5 triiodothyronine (T3) to prevent I/R renal injury. METHODOLOGY/PRINCIPAL FINDINGS THE RATS WERE DIVIDED INTO FOUR GROUPS: sham-operated, placebo-treated (SO-P), sham-operated T3- treated (SO- T3), I/R-injured placebo-treated (IR-P), and I/R-injured T3-treated (IR- T3) groups. At 24 h before ischemia, the animals received a single dose of T3 (100 μg/kg). Renal function and plasma, urinary, and tissue variables were studied at 4, 24, and 48 h of reperfusion, including biochemical, oxidative stress, and inflammation variables, PARP-1 immunohistochemical expression, and ATN morphology. In comparison to the SO groups, the IR-P groups had higher plasma urea and creatinine levels and greater proteinuria (at all reperfusion times) and also showed: increased oxidative stress-related plasma, urinary, and tissue variables; higher plasma levels of IL6 (proinflammatory cytokine); increased glomerular and tubular nuclear PARP-1 expression; and a greater degree of ATN. The IR-T3 group showed a marked reduction in all of these variables, especially at 48 h of reperfusion. No significant differences were observed between SO-P and SO-T3 groups. CONCLUSIONS This study demonstrates that preconditioning rats with a single dose of T3 improves the clinical signs and ATN of renal I/R injury. These beneficial effects are accompanied by reductions in oxidative stress, inflammation, and renal PARP-1 expression, indicating that this sequence of factors plays an important role in the ATN induced by I/R injury.