Quantitative analysis by renormalized entropy of invasive electroencephalograph recordings in focal epilepsy

Invasive electroencephalograph (EEG) recordings of ten patients suffering from focal epilepsy were analyzed using the method of renormalized entropy. Introduced as a complexity measure for the different regimes of a dynamical system, the feature was tested here for its spatio-temporal behavior in epileptic seizures. In all patients a decrease of renormalized entropy within the ictal phase of seizure was found. Furthermore, the strength of this decrease is monotonically related to the distance of the recording location to the focus. The results suggest that the method of renormalized entropy is a useful procedure for clinical applications like seizure detection and localization of epileptic foci.Comment: 10 pages, 5 figure

'MRI-negative PET-positive' temporal lobe epilepsy (TLE) and mesial TLE differ with quantitative MRI and PET: a case control study

Background: \u27MRI negative PET positive temporal lobe epilepsy\u27 represents a substantial minority of temporal lobe epilepsy (TLE). Clinicopathological and qualitative imaging differences from mesial temporal lobe epilepsy are reported. We aimed to compare TLE with hippocampal sclerosis (HS+ve) and non lesional TLE without HS (HS-ve) on MRI, with respect to quantitative FDG-PET and MRI measures.Methods: 30 consecutive HS-ve patients with well-lateralised EEG were compared with 30 age- and sex-matched HS+ve patients with well-lateralised EEG. Cerebral, cortical lobar and hippocampal volumetric and co-registered FDG-PET metabolic analyses were performed.Results: There was no difference in whole brain, cerebral or cerebral cortical volumes. Both groups showed marginally smaller cerebral volumes ipsilateral to epileptogenic side (HS-ve 0.99, p = 0.02, HS+ve 0.98, p &lt; 0.001). In HS+ve, the ratio of epileptogenic cerebrum to whole brain volume was less (p = 0.02); the ratio of epileptogenic cerebral cortex to whole brain in the HS+ve group approached significance (p = 0.06). Relative volume deficits were seen in HS+ve in insular and temporal lobes. Both groups showed marked ipsilateral hypometabolism (p &lt; 0.001), most marked in temporal cortex. Mean hypointensity was more marked in epileptogenic-to-contralateral hippocampus in HS+ve (ratio: 0.86 vs 0.95, p &lt; 0.001). The mean FDG-PET ratio of ipsilateral to contralateral cerebral cortex however was low in both groups (ratio: HS-ve 0.97, p &lt; 0.0001; HS+ve 0.98, p = 0.003), and more marked in HS-ve across all lobes except insula.Conclusion: Overall, HS+ve patients showed more hippocampal, but also marginally more ipsilateral cerebral and cerebrocortical atrophy, greater ipsilateral hippocampal hypometabolism but similar ipsilateral cerebral cortical hypometabolism, confirming structural and functional differences between these groups.<br /

Sur les premiers peuplements du Pacifique sud

About the first human settlements in South Pacific. South Pacific includes Australia and the Pacific Islands: Melanesia, Micronesia, Polynesia. Which human populations settled them? When, why and how? Where did they come from? Did environment influence these migrations? An exhaustive discussion of these vast questions could not be undertaken rigorously within the framework of this short article. We thus propose to discuss here very precise points that could bring a new lighting on the first settlements of South Pacific. According to the oldest archaeological sites of Australia, first arrivals of Homo sapiens in the area occurred at least 40 000 years ago, and possibly as early as 50 to 60 ka BP. From a palaeoanthropological point of view, the question of the origin of these anatomically modem H. sapiens is under debate for several years: did they come from a relatively recent 'out of Africa' migration (Out-of-Africa hypothesis) or did they evolve locally from the last Indonesian H. erectus (multiregional hypothesis)? Partisans of these two models disagree on several fundamental points, and particularly on the interpretation of certain morphometric affinities between the most recent Indonesian H. erectus and the 'robust' Australian fossil H. sapiens from Kow Swamp and Cohuna. The application of 3D geometric morphometrics (Procrustes analysis) makes it possible to approach this question under a new angle. The shapes of these two sets of fossil hominids are clearly distinct, questioning seriously the assumption of a local direct evolution. For these oldest human settlements as well as for later migrations, multidisciplinary studies (archaeology, palaeoenvironment, palacoanthropology, genetic, and linguistic) allow us to reconstruct the outlines of the first human settlements of these areas. Climate and environment interacted with these migrations of populations. The very first example is the formation of land bridges between Asian mainland and the Indonesian archipelago during Quaternary glaciations allowing the passage of humans and fauna. And periods of lower sea levels possibly also favoured dispersion from islands to islands. Winds and sea currents, directly related with climate and its variations, also intervened in the settlement of the Pacific. Natural environment, which is impoverished eastward, has been enriched by animals and plants transported by humans. In relation to their way of life as well as to available resources, peoples initially settled littoral zones (Lapita sites), then moved inland very quickly, as demonstrated by excavations carried out in the North of Grande Terre, New Caledonia. To cite this article: A.-M. Simah, C. R. Palevol 5 (2006). (c) 2006 Academie des sciences. Publie par Elsevier SAS. Tons droits reserves

PET evidence for a role of the basal ganglia in patients with ring chromosome 20 epilepsy.

BACKGROUND: Studies in animal models and epileptic patients have suggested that circuits of the basal ganglia may control epileptic seizures and that striatal dopaminergic transmission plays a key role in seizure interruption. Ring chromosome 20 (r[20]) epilepsy is a very homogenous type of epilepsy and is clinically characterized by long-lasting seizures suggesting a dysfunction in the seizure control system. The hypothesis that these long-lasting seizures are associated with a reduction of striatal dopamine was addressed in the present study in drug-resistant patients with r(20) epilepsy using PET. METHOD: The authors performed [18F]fluoro-l-DOPA PET in 14 patients with r(20) epilepsy and compared uptake constants in the putamen and the caudate with those of 10 controls. In addition, the authors examined the correlation between these constants and the percentage of cells with r(20) mosaicism. RESULTS: [18F]fluoro-l-DOPA uptake was significantly decreased bilaterally in the putamen and in the caudate nucleus of patients. This reduction was equal for both nuclei and was not correlated to the percentage of cells with r(20). CONCLUSION: Striatal dopamine is modulated in r(20) epilepsy; dysfunction of this neurotransmission may impair the mechanisms that interrupt seizures