Showing papers by "François Mauguière published in 1996"

A controlled positron emission tomography study of obsessive and neutral auditory stimulation in obsessive-compulsive disorder with checking rituals

Abstract: Ten nondepressed patients with obsessive-compulsive disorder (OCD) who were characterized by predominant checking rituals were compared with 10 age- and sex-matched control subjects. Hemispheric and regional cerebral blood flow levels (rCBF) were measured with positron emission tomography (H2 15O) across four conditions: rest, auditory stimulation with idiosyncratic normal or abnormal obsession, auditory stimulation with neutral verbal stimuli, and rest. Order of neutral and obsessive stimulation was randomized. Higher subjective responses to obsessive than to neutral stimulation were found in both groups; subjective response was higher in OCD patients when obsessive stimulation was presented first. A four-way analysis of variance (group x stimulation order x hemisphere x condition [neutral or obsessive stimulation]) was performed on stimulation minus rest normalized rCBF values. Control subjects had significantly higher rCBF in the thalamus and putamen. A trend toward higher rCBF in OCD patients was found in the superior temporal regions. When neutral stimulation was presented first, rCBF was significantly higher in the caudate region of control subjects. Obsessive stimulation was associated with higher rCBF than neutral stimulation in orbitofrontal regions in both groups of subjects. Under obsessive stimulation, superior temporal and orbitofrontal activities were correlated in OCD patients but not in control subjects. Our study suggests specific abnormalities of information processing in the basal ganglia and temporal structures of compulsive checkers.

Source propagation of interictal spikes in temporal lobe epilepsy. Correlations between spike dipole modelling and [18F]fluorodeoxyglucose PET data.

Abstract: Source localization methods were applied to interictal spikes from scalp EEGs and correlated with metabolic (PET scan) data in eight patients suffering from drug-resistant temporal lobe epilepsy (TLE). Dipolar sources, [18F]fluorodeoxy-glucose (18FDG)-PET data and anatomical images (MRI) were projected into the same three-dimensional coordinates system. Averaged spikes were adequately modelled by two or three dipolar sources with different onset time of activation but overlapping activity (mean residual variance 3.4±2.1%). Although, in all patients, spike modelling demonstrated dipolar sources in both mesial and lateral temporal cortex, dipole propagation was consistent with the early involvement of only one of these two areas (mesio-temporal, five patients; lateral and polar neocortex, three patients). Six patients showed a unilateral interictal decrease in glucose uptake, as measured with 18FDG-PET, in the temporal lobe ipsilateral to the EEG spike focus. Temporal hypometabolism was bilateral in one patient and absent in the remaining case. When projected onto PET-scan slices, the dipolar sources of these patients were always included within the hypometabolic area. However, within the hypometabolic zone, the decrease in glucose uptake was not found to be more pronounced in regions containing dipoles. Therefore the spatio-temporal spread of neuronal hyperactivity underlying interictal spiking suggests the presence of preferential epileptogenic networks inside the hypometabolic temporal lobe. Fusion of bioelectric, metabolic and anatomical data proves to be a convenient way of summarizing multimodal information from non-invasive investigations in TLE patients entering an epilepsy surgery programme, and suggests that both interictal spike dipole modelling and 18FDG-PET data might be useful, as a complement to ictal electro-clinical data, in the presurgical evaluation of such patients.

Neural generators of tibial nerve P30 somatosensory evoked potential studied in patients with a focal lesion of the cervicomedullary junction.

Abstract: The tibial nerve P30 potential was studied in 6 patients with focal lesions located in the vicinity of the cervicomedullary junction. P30 potential was unaffected while cortical P39 was abnormal in the patients with a supramedullary lesion affecting the somatosensory pathway just above its decussation. Conversely, P30 was abnormal in the presence of a lesion situated caudally to the cervicomedullary junction affecting the lower limb sensory fibers just below their decussation. Median nerve P14 behaved similarly to the P30 potential in these cases. These clinical observations suggest that P30 potential, as P14 of median nerve somatosensory evoked potentials, is generated in the lower brain stern probably before the decussation of the sensory fibers; nucleus gracilis and medial lemniscus fibers in the lower brain stem are probably the anatomical structures generating P30 potential. This suggests that P30 potential may be used to study intraspinal and intracranial conduction times separately in the afferent somatosensory pathways. © 1996 John Wiley & Sons, Inc.

Exploration par les potentiels évoqués moteurs (PEM) des tumeurs intrarachidiennes : corrélations avec les données des potentiels évoqués somesthésiques (PES)

Abstract: MEPs to transcutaneous magnetic stimulation have been recorded in 43 patients with an intraspinal tumor documented by MRI. The tumor was extramedullary in 18 patients and intramedullary In 25. MEPs were abnormal in 62.8% of patients. There were no significant differences in the rate of MEP abnormalities according to the lesion site or the histological findings, except for meningiomas which showed abnormal MEPs in all eight patients included in this series. The percentage of patients with abnormal MEPs was 9.3% despite the absence of any clinical symptom of central motor pathway dysfunction. Infraclinical MEPs abnormalities were observed in 24% of explored limbs. Median and tibial nerves somatosensory evoked potentials (SEPs) were recorded in 41 patients and showed abnormalities of central conduction or of segmental spinal responses in 65.9% of the cases. When combining data from MEP and SEPs, abnormalities were observed in 70.7% of patients (29/41). Five patients (12.2%) had abnormal MEPs, but normal SEPs, and four other patients (9.8%) had abnormal SEPs, but normal MEPs. This finding suggests that both MEPs and SEPs should be recorded for presurgical evaluation of-intraspinal tumor.

Optimisation des images hippocampiques de captation glucidique par tomogrpahie d'émission de positons dans l'épilepsie du lobe temporal

Abstract: Au cours de l'epilepsie du lobe temporal (ELT), une origine hippocampique est frequemment evoquee. Pour ameliorer la resolution des structures hippocampiques lors de l'etude du metabolisme cerebral a l'aide du [ 18 F]-fluoro-2-D-desoxyglucose (FDG) en tomographie d'emission de positons (TEP), nous avons explore les effets de l'acquisition des coupes TEP selon des plans paralleles a l'axe longitudinal de l'hippocampe (HIP). Nous avons etudie successivement 16 patients porteurs d'ELT et trois sujets volontaires normaux en imagerie par resonance magnetique (IRM) et par TEP. En utilisant l'information anatomique fournie par l'etude IRM, l'examen TEP a ete realise selon deux orientations de coupes : l'une parallele a la ligne orbito-meatale (plan OM) et l'autre parallele au plan des hippocampes. Les images TEP obtenues dans le plan HIP se sont revelees plus riches, a la fois sous les aspects qualitatifs et quantitatifs, que celles obtenues dans le plan OM pour etudier le metabolisme glucidique dans les structures temporales. L'orientation hippocampique est donc utile pour les acquisitions FDG en TEP, lorsque le siege des crises peut se situer dans les structures mesio-temporales.