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Objective: To investigate brain changes in both basal and cataplectic conditions in awake patients with narcolepsy-cataplexy.Background: Recent insights in pathophysiology have demonstrated that narcolepsy-cataplexy is caused by early loss of hypothalamus hypocretin neurons. However, the neurophysiological mechanisms underlying sleepiness and the dramatic cataplexy reaction to positive emotion remain unclear.Methods: Twenty-one patients with narcolepsy-cataplexy and 21 age- and sex-matched controls were included. Diagnosis of narcolepsy was fully confirmed by polysomnography, HLA DQB1*0602 and CSF hypocretin levels (n=9). Seven patients were free of all drugs, and 14 were treated with psychostimulant and/or anticataplectic drugs. (18)-F-fluorodeoxy glucose positron emission tomography procedures were performed at baseline in all subjects and during cataplexy attacks (n=2).Results: The authors found significant hypermetabolism in narcolepsy-cataplexy in fully awake condition in the limbic cortex specifically in the anterior and mid cingulate cortex, in the right cuneus and lingual gyrus. In contrast, no hypometabolism was found. Hypermetabolism was detected in the cerebellum and pre-postcentral gyri in treated compared with untreated patients. During cataplectic attacks, cerebral metabolism significantly increased in the bilateral pre-postcentral gyri, primary somatosensory cortex, with a marked decrease in the hypothalamus.Conclusion: Hypermetabolism was found in the executive network in narcolepsy at baseline in fully awake condition. Wake state assessment during scanning appears critical to avoid results showing altered functional neurocircuitry secondary to sleepiness and not to the underlying neurological disorder per se. Finally, cataplexy attacks were characterised by a hypometabolism in the hypothalamus associated with wide bilateral brain area hypermetabolisms. [ABSTRACT FROM AUTHOR]

Abstract. The aim of this preliminary study was to evaluate the accuracy of left and right ventricular output computed from a semi-automatic processing of tomographic radionuclide ventriculography data (TRVG) in comparison with the conventional thermodilution method. Twenty patients with various heart diseases were prospectively included in the study. Thermodilution and TRVG acquisitions were carried out on the same day for all patients. Analysis of gated blood pool slices was performed using a watershed-based segmentation algorithm. Right and left ventricular output measured by TRVG correlated well with the measurements obtained with thermodilution (r=0.94 and 0.91 with SEE=0.38 and 0.46 1/min, respectively, P<0.001). The limits of agreement for TRVG and thermodilution measurements were -0.78-1.20 1/min for the left ventricle and -0.34-1.16 1/min for the right ventricle. No significant difference was found between the results of TRVG and thermodilution with respect to left ventricular output (P=0.09). A small but significant difference was found between right ventricular output measured by TRVG and both left ventricular output measured by TRVG (mean difference=0.17 1/min, P=0.04) and thermodilution-derived cardiac output (mean difference=0.41 1/min, P=0.0001). It is concluded that the watershed-based semi-automatic segmentation of TRVG slices provides non-invasive measurements of right and left ventricular output and stroke volumes at... [ABSTRACT FROM AUTHOR]

Regional cerebral blood flow (rCBF) measurements were determined by the intravenous Xenon 133 technique in 80 patients suffering from temporal lobe epilepsy. All the patients had a normal CT scan. Three subgroups were differentiated, according to EEG and all-night polygraphic recordings: temporal lobe epilepsy with left (N = 25) or right (N = 25) EEG epileptic abnormalities and temporal lobe epilepsy with EEG abnormalities in both temporal regions with asynchronous occurrence (n = 30). In comparison with a control group (n = 20), there was (1) a marked reduction of blood flow in the temporal region corresponding to the site of the epileptic focus and (2) a reduction in blood flow in distant brain areas and the contralateral hemisphere. The rCBF decrease was highly correlated (p less than 0.001) with the disease severity (taking into account the complex partial seizure frequency and the number of secondary generalised seizures). Differences were found in the rCBF decrease between left and right temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]