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See detailZerebrale Funktionen bei hirngeschädigten Patienten. Was bedeuten Koma, "vegetative state“, "minimally conscious state“, "Locked-in-Syndrom“ und Hirntod?
Faymonville, Marie-Elisabeth ULg; Pantke, Karl-Heinz; Berré, Jacques et al

in Anaesthesist (2004), 53(12), 1195-1202

Comatose, vegetative, minimally conscious or locked-in patients represent a problem in terms of diagnosis, prognosis, treatment and everyday management at the intensive care unit. The evaluation of ... [more ▼]

Comatose, vegetative, minimally conscious or locked-in patients represent a problem in terms of diagnosis, prognosis, treatment and everyday management at the intensive care unit. The evaluation of possible cognitive functions in these patients is difficult because voluntary movements may be very small, inconsistent and easily exhausted. Functional neuroimaging cannot replace the clinical assessment of patients with altered states of consciousness. Nevertheless, it can describe objectively how deviant from normal the cerebral activity is and its regional distribution at rest and under various conditions of stimulation. The quantification of brain activity differentiates patients who sometimes only differ by a brief and incomplete blink of an eye. In the present paper, we will first try to define consciousness as it can be assessed at the patient's bedside. We then review the major clinical entities of altered states of consciousness encountered in the intensive care unit. Finally, we discuss the functional neuroanatomy of these conditions as assessed by positron emission tomography (PET) scanning. [less ▲]

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See detailEffects of Alzheimer's disease on the recognition of novel versus familiar words : Neuropsychological and clinico-metabolic data
Lekeu, Françoise ULg; Van der Linden, Martial ULg; Degueldre, Christian ULg et al

in Neuropsychology (2003), 17(1), 143-154

This study explored recognition memory performance for novel versus familiar words in Alzheimer's disease (AD) patients and normal controls (NCs), using an adaptation of E. Tulving and N. Kroll's (1995 ... [more ▼]

This study explored recognition memory performance for novel versus familiar words in Alzheimer's disease (AD) patients and normal controls (NCs), using an adaptation of E. Tulving and N. Kroll's (1995) procedure. Results showed that both groups exhibited more hits and more false alarms for familiar than for novel words. The groups did not differ in the recognition of familiar words, reflecting preserved familiarity processes in AD. However, AD patients made more false alarms than NCs in the recognition of novel words, reflecting impairment of recollection processes in AD. A positron emission tomography analysis of clinico-metabolic correlations in AD patients showed a correlation between recognition of novel words and right hippocampal activity, whereas recognition of familiar words was more related to metabolic activity in the left posterior orbitofrontal cortex. [less ▲]

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See detailBrain correlates of performance in a free/cued recall task with semantic encoding in Alzheimer disease
Lekeu, Françoise ULg; Van der Linden, Martial ULg; Chicherio, C. et al

in Alzheimer Disease and Associated Disorders (2003), 17(1), 35-45

The goal of this study was to explore in patients with Alzheimer's disease (AD) the brain correlates of free and cued recall performance using an adaptation of the procedure developed by Grober and ... [more ▼]

The goal of this study was to explore in patients with Alzheimer's disease (AD) the brain correlates of free and cued recall performance using an adaptation of the procedure developed by Grober and Buschke (1987). This procedure, which ensures semantic processing and coordinates encoding and retrieval, has been shown to be very sensitive to an early diagnosis of AD. Statistical parametric mapping (SPM 99) was used to establish clinicometabolic correlations between performance at free and cued verbal recall and resting brain metabolism in 31 patients with AD. Results showed that patient's score on free recall correlated with metabolic activity in right frontal regions (BA 10 and BA 45), suggesting that performance reflected a strategic retrieval attempt. Poor retrieval performance was tentatively attributed to a loss of functional correlation between frontal and medial temporal regions in patients with AD compared with elderly controls. Performance on cued recall was correlated to residual metabolic activity in bilateral parahippocampal regions (BA 36), suggesting that performance reflected retrieval of semantic associations, without recollection in AD. In conclusion, this study demonstrates that the diagnostic sensitivity for Alzheimer's disease of the cued recall performance in the Grober and Buschke procedure (1987) depends on the activity of parahippocampal regions, one of the earliest targets of the disease. Moreover, the results suggest that the poor performance of patients with AD during free and cued recall is related to a decreased connectivity between parahippocampal regions and frontal areas. [less ▲]

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See detailBrain function in the vegetative state
Laureys, Steven ULg; Antoine, S.; Boly, Mélanie ULg et al

in Acta Neurologica Belgica (2002), 102(4), 177-185

Positron emission tomography (PET) techniques represent a useful tool to better understand the residual brain function in vegetative state patients. It has been shown that overall cerebral metabolic rates ... [more ▼]

Positron emission tomography (PET) techniques represent a useful tool to better understand the residual brain function in vegetative state patients. It has been shown that overall cerebral metabolic rates for glucose are massively reduced in this condition. However, the recovery of consciousness from vegetative state is not always associated with substantial changes in global metabolism. This finding led us to hypothesize that some vegetative patients are unconscious not just because of a global loss of neuronal function, but rather due to an altered activity in some critical brain regions and to the abolished functional connections between them. We used voxel-based Statistical Parametric Mapping (SPM) approaches to characterize the functional neuroanatomy of the vegetative state. The most dysfunctional brain regions were bilateral frontal and parieto-temporal associative cortices. Despite the metabolic impairment, external stimulation still induced a significant neuronal activation (i.e., change in blood flow) in vegetative patients as shown by both auditory click stimuli and noxious somatosensory stimuli. However this activation was limited to primary cortices and dissociated from higher-order associative cortices, thought to be necessary for conscious perception. Finally, we demonstrated that vegetative patients have impaired functional connections between distant cortical areas and between the thalami and the cortex and, more importantly, that recovery of consciousness is paralleled by a restoration of this cortico-thalamo-cortical interaction. [less ▲]

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See detailCortical processing of noxious somatosensory stimuli in the persistent vegetative state
Laureys, Steven ULg; Faymonville, Marie-Elisabeth ULg; Peigneux, Philippe ULg et al

in NeuroImage (2002), 17(2), 732-741

The persistent vegetative state (PVS) is a devastating medical condition characterized by preserved wakefulness contrasting with absent voluntary interaction with the environment. We used positron ... [more ▼]

The persistent vegetative state (PVS) is a devastating medical condition characterized by preserved wakefulness contrasting with absent voluntary interaction with the environment. We used positron emission tomography to assess the central processing of noxious somatosensory stimuli in the PVS. Changes in regional cerebral blood flow were measured during high-intensity electrical stimulation of the median nerve compared with rest in 15 nonsedated patients and in 15 healthy controls. Evoked potentials were recorded simultaneously. The stimuli were experienced as highly unpleasant to painful in controls. Brain glucose metabolism was also studied with [F-18]fluorodeoxyglucose in resting conditions. In PVS patients, overall cerebral metabolism was 40% of normal values. Nevertheless, noxious somatosensory stimulation-activated midbrain, contralateral thalamus, and primary somatosensory cortex in each and every PVS patient, even in the absence of detectable cortical evoked potentials. Secondary somatosensory, bilateral insular, posterior parietal, and anterior cingulate cortices did not show activation in any patient. Moreover, in PVS patients, the activated primary somatosensory cortex was functionally disconnected from secondary somatosensory, bilateral posterior parietal, premotor, polysensory superior temporal, and prefrontal cortices. In conclusion, somatosensory stimulation of PVS patients, at intensities that elicited pain in controls, resulted in increased neuronal activity in primary somatosensory cortex, even if resting brain metabolism was severely impaired. However, this activation of primary cortex seems to be isolated and dissociated from higher-order associative cortices. (C) 2002 Elsevier Science (USA). [less ▲]

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See detailEffects of incidental and intentional feature binding on recognition: a behavioural and PET activation study
Lekeu, Françoise ULg; Van der Linden, Martial ULg; Collette, Fabienne ULg et al

in Neuropsychologia (2002), 40(2), 131-144

Using Positron Emission Tomography (PET), we investigated cerebral regions associated with the episodic recognition of words alone and words bound to contextual colours. Two modes of colour encoding were ... [more ▼]

Using Positron Emission Tomography (PET), we investigated cerebral regions associated with the episodic recognition of words alone and words bound to contextual colours. Two modes of colour encoding were tested: incidental and intentional word-to-colour binding. Word-only recognition was associated with brain activation in a lexico-semantic left middle temporal region and in the cerebellum following an incidental colour encoding, and with brain activation in the left posterior middle frontal gyrus, right anterior cingulate and right inferior frontal gyrus following an intentional encoding. Recognition of bound features was associated with activation in left prefrontal and superior parietal regions following an incidental colour encoding, and with preferential right prefrontal cortex activation following an intentional colour encoding. Our results are in line with the hypothesis of a parietal involvement in context processing, and prefrontal areas in monitoring retrieval processes. Our results also support the hypothesis of a 'cortical asymmetry for reflective activity' (CARA). [less ▲]

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See detailNeural and cognitive bases of upper limb apraxia in corticobasal degeneration
Peigneux, Philippe ULg; Salmon, Eric ULg; Garraux, Gaëtan ULg et al

in Neurology (2001), 57(7), 1259-1268

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment ... [more ▼]

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment of apraxia and resting [(18)F]-fluorodeoxyglucose PET scanning. Two complementary measures of apraxia were computed for each modality of gesture production. First, a performance score measured error frequency during gesture execution. Second, as a more stringent test of the integrity of the praxis system, the correction score measured the patient's ability to correct his or her errors on a second attempt. For each measure type, a cut-off score for the presence of apraxia was defined with regard to healthy controls. Using each cut-off score, the regional cerebral glucose metabolism of patients with CBD with apraxia (i.e., performing below cut-off score) was compared with that of patients with CBD without apraxia. RESULTS: Mean performance scores were below normal values in all modalities. Anterior cingulate hypometabolism predominated in patients with CBD who performed below the cut-off performance score. At variance, mean correction scores were below normal values for gesture imitation only. Hypometabolism in superior parietal lobule and supplementary motor area characterized patients with CBD who were unable to correct their errors at the same rate as control subjects did. CONCLUSIONS: Distinct neural networks underlie distinct aspects of the upper limb apraxic deficits in CBD. Extending previous findings of gesture production deficits in CBD, the use of complementary measures of apraxic behavior discloses a visuoimitative upper limb apraxia in CBD, underlain by a metabolic decrease in a parietofrontal neural network. [less ▲]

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See detailVoxel-based distribution of metabolic impairment in corticobasal degeneration
Garraux, Gaëtan ULg; Salmon, Eric ULg; Peigneux, Philippe ULg et al

in Movement Disorders (2000), 15(5), 894-904

This report emphasizes the precise topographic distribution of cerebral metabolic impairment in corticobasal degeneration (CBD) and the pathophysiological differences between CBD and progressive ... [more ▼]

This report emphasizes the precise topographic distribution of cerebral metabolic impairment in corticobasal degeneration (CBD) and the pathophysiological differences between CBD and progressive supranuclear palsy (PSP). Statistical parametric mapping (SPM96) analysis of 18FDG positron emission tomography (PET) data was performed in 22 patients with CBD compared with 46 healthy subjects (HS) and 21 patients with PSP who were studied at rest. A statistical threshold of p <0.001 was fixed, further corrected for multiple or independent comparisons (p <0.05). In comparison with HS, the metabolic impairment in CBD was asymmetrically distributed in the putamen, thalamus, precentral (Brodmann's area, BA 4), lateral premotor (BA 6/44) and supplementary motor areas (SMA, BA 6), dorsolateral prefrontal (8/9/46) cortex, and the anterior part of the inferior parietal lobe (BA 40) including the intraparietal sulcus (BA 7/40). A similar hypometabolic pattern was observed for most individual analyses. When PSP was compared with CBD, metabolic impairment predominated in the midbrain, anterior cingulate (BA 24/32), and orbitofrontal regions (BA 10). The reverse contrast showed more posterior involvement in CBD (BA 6 and 5/7/40) including SMA. Our data suggest that multiple components of neural networks related to both movement execution and production of skilled movements are functionally disturbed in CBD compared with both HS and PSP. [less ▲]

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See detailStriatum forever, despite sequence learning variability : A random effect analysis of PET data
Peigneux, Philippe ULg; Maquet, Pierre ULg; Meulemans, Thierry ULg et al

in Human Brain Mapping (2000), 10(4), 179-194

This PET study is concerned with the what, where, and how of implicit sequence learning. In contrast with previous studies imaging the serial reaction time (SRT) task, the sequence of successive locations ... [more ▼]

This PET study is concerned with the what, where, and how of implicit sequence learning. In contrast with previous studies imaging the serial reaction time (SRT) task, the sequence of successive locations was determined by a probabilistic finite-state grammar. The implicit acquisition of statistical relationships between serially ordered elements (i.e., what) was studied scan by scan, aiming to evidence the brain areas (i.e., where) specifically involved in the implicit processing of this core component of sequential higher-order knowledge. As behavioural results demonstrate between- and within-subjects variability in the implicit acquisition of sequential knowledge through practice, functional PET data were modelled using a random-effect model analysis (i.e., how) to account for both sources of behavioural variability. First, two mean condition images were created per subject depending on the presence or not of implicit sequential knowledge at the time of each of the 12 scans. Next, direct comparison of these mean condition images provided the brain areas involved in sequential knowledge processing. Using this approach, we have shown that the striatum is involved in more than simple pairwise associations and that it has the capacity to process higher-order knowledge. We suggest that the striatum is not only involved in the implicit automatization of serial information through prefrontal cortex-caudate nucleus networks, but also that it plays a significant role for the selection of the most appropriate responses in the context created by both the current and previous stimuli, thus contributing to better efficiency and faster response preparation in the SRT task. Hum. Brain Mapping 10:179-194, 2000. © 2000 Wiley-Liss, Inc. [less ▲]

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See detailExperience-dependent changes in cerebral activation during human REM sleep
Maquet, Pierre ULg; Laureys, Steven ULg; Peigneux, Philippe ULg et al

in Nature Neuroscience (2000), 3(8), 831-836

The function of rapid-eye-movement (REM) sleep is stiil unknown. One prevailing hypothesis suggests that REM sleep is important in processing memory traces. Here, using positron emission tomography (PET ... [more ▼]

The function of rapid-eye-movement (REM) sleep is stiil unknown. One prevailing hypothesis suggests that REM sleep is important in processing memory traces. Here, using positron emission tomography (PET) and regional cerebral blood flow measurements, we show that waking experience influences regional brain activity during subsequent sleep. Several brain areas activated during the execution of a serial reaction time task during wakefulness were significantly more active during REM sleep in subjects previously trained on the task than in non-trained subjects. These results support the hypothesis that memory traces are processed during REM sleep in humans. [less ▲]

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See detailExploration neuropsychologique et par imagerie fonctionnelle cérébrale d'une apraxie visuo-imitative
Peigneux, Philippe ULg; Van der Linden, Martial ULg; Andres-Benito, P. et al

in Revue Neurologique (2000), 156(5), 459-472

We describe the case of a 58-years-old right-handed women suffering from an occipital-parietal lesion. The administration of a cognitively based assessment tool for limb praxis (Batterie d'Evaluation des ... [more ▼]

We describe the case of a 58-years-old right-handed women suffering from an occipital-parietal lesion. The administration of a cognitively based assessment tool for limb praxis (Batterie d'Evaluation des Praxies, B.E.P., Peigneux and Van der Linden, 1998) demonstrated bilateral visuo-imitative apraxia. Gesture production was mainly characterised by spatial, errors, and imitation of meaningful gestures was worse than their pantomime on verbal command. Moreover, the imitation of meaningless gestures and their reproduction on a manikin were worse than imitation of their matched meaningful gestures. In a cognitive perspective, adapted from the Rothi et al. (1997) and Goldenberg (1995) contributions to our understanding of limb praxis, this configuration of performance suggests deficits occurring at multiple levels. On one hand, it suggests either access difficulties or alteration of the output praxicon, i.e., the lexicon for visuo-kinesthetic engrams of meaningful gestures. On the other hand, the simultaneous deficit for meaningless gesture reproduction on the subject's own body and on a manikin favors an alteration of the structural descriptions of the human body (i.e., human body knowledge), underlying the mental transposition processes occurring between the visual analysis of a meaningless gestural configuration and its effective reproduction on oneself or on a manikin, thus contradicting the classic view of a direct pathway linking visual analysis and motor planning in meaningless gesture imitation. Finally, due to the output praxicon deficit, imitation of meaningful gestures is partly processed in the same way as meaningless gestures (also impaired in this case), leading to an interference effect between both degraded memory-based and visually-transposed traces, which account for imitation of meaningful gestures being worse than their pantomime on verbal command. We also assess regional cerebral metabolism using positron emission tomography (PET). Comparison with 41 healthy subjects (SPM96) demonstrated a statistically significant hypometabolism in the left intraparietal sulcus and superior parietal lobule, and in the right dorsal prestriate cortex. These results, together with a review of the other studies of visuo-imitative apraxia, suggest that the left intraparietal sulcus may be associated with access or integration of information from the output praxicon. The left superior parietal and the right dorsal prestriate deficits functionally impaired a bilateral dorsal network implied in the mental transformations of the body, thus suggesting that these mental transformations are underlined by knowledge of the human body, which may subsequently explain the deficit for the reproduction of meaningless and meaningful configurations. [less ▲]

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See detailNeural mechanisms of antinociceptive effects of hypnosis.
Faymonville, Marie ULg; Laureys, Steven ULg; Degueldre, Christian ULg et al

in Anesthesiology (2000), 92(5), 1257-67

BACKGROUND: The neural mechanisms underlying the modulation of pain perception by hypnosis remain obscure. In this study, we used positron emission tomography in 11 healthy volunteers to identify the ... [more ▼]

BACKGROUND: The neural mechanisms underlying the modulation of pain perception by hypnosis remain obscure. In this study, we used positron emission tomography in 11 healthy volunteers to identify the brain areas in which hypnosis modulates cerebral responses to a noxious stimulus. METHODS: The protocol used a factorial design with two factors: state (hypnotic state, resting state, mental imagery) and stimulation (warm non-noxious vs. hot noxious stimuli applied to right thenar eminence). Two cerebral blood flow scans were obtained with the 15O-water technique during each condition. After each scan, the subject was asked to rate pain sensation and unpleasantness. Statistical parametric mapping was used to determine the main effects of noxious stimulation and hypnotic state as well as state-by-stimulation interactions (i.e., brain areas that would be more or less activated in hypnosis than in control conditions, under noxious stimulation). RESULTS: Hypnosis decreased both pain sensation and the unpleasantness of noxious stimuli. Noxious stimulation caused an increase in regional cerebral blood flow in the thalamic nuclei and anterior cingulate and insular cortices. The hypnotic state induced a significant activation of a right-sided extrastriate area and the anterior cingulate cortex. The interaction analysis showed that the activity in the anterior (mid-)cingulate cortex was related to pain perception and unpleasantness differently in the hypnotic state than in control situations. CONCLUSIONS: Both intensity and unpleasantness of the noxious stimuli are reduced during the hypnotic state. In addition, hypnotic modulation of pain is mediated by the anterior cingulate cortex. [less ▲]

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See detailThe role of lateral occipitotemporal junction and area MT/V5 in the visual analysis of upper-limb postures
Peigneux, Philippe ULg; Salmon, Eric ULg; Van der Linden, Martial ULg et al

in Neuroimage (2000), 11(6), 644-655

Humans, like numerous other species, strongly rely on the observation of gestures of other individuals in their everyday life. It is hypothesized that the visual processing of human gestures is sustained ... [more ▼]

Humans, like numerous other species, strongly rely on the observation of gestures of other individuals in their everyday life. It is hypothesized that the visual processing of human gestures is sustained by a specific functional architecture, even at an early prelexical cognitive stage, different from that required for the processing of other visual entities. In the present PET study, the neural basis of visual gesture analysis was investigated with functional neuroimaging of brain activity during naming and orientation tasks performed on pictures of either static gestures (upper-limb postures) or tridimensional objects. To prevent automatic object-related cerebral activation during the visual processing of postures, only intransitive postures were selected, i.e., symbolic or meaningless postures which do not imply the handling of objects. Conversely, only intransitive objects which cannot be handled were selected to prevent gesture-related activation during their visual processing. Results clearly demonstrate a significant functional segregation between the processing of static intransitive postures and the processing of intransitive tridimensional objects. Visual processing of objects elicited mainly occipital and fusiform gyrus activity, while visual processing of postures strongly activated the lateral occipitotemporal junction, encroaching upon area MT/V5, involved in motion analysis. These findings suggest that the lateral occipitotemporal junction, working in association with area MT/V5, plays a prominent role in the high-level perceptual analysis of gesture, namely the construction of its visual representation, available for subsequent recognition or imitation. (C) 2000 Academic Press. [less ▲]

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See detailRestoration of thalamocortical connectivity after recovery from persistent vegetative state
Laureys, Steven ULg; Faymonville, Marie-Elisabeth ULg; Luxen, André ULg et al

in Lancet (2000), 355(9217), 1790-1791

Moreover, the performance on these factors is correlated to different anterior and posterior

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See detailMedial temporal lobe metabolic impairment in dementia associated with motor neuron disease
Garraux, Gaëtan ULg; Salmon, Eric ULg; Degueldre, Christian ULg et al

in Journal of the Neurological Sciences (1999), 168(2), 145-150

In the course of their disease certain patients with frontotemporal dementia (FTD) develop clinical features compatible with a motor neuron disease (FTD-MND). Previous reports have suggested that the ... [more ▼]

In the course of their disease certain patients with frontotemporal dementia (FTD) develop clinical features compatible with a motor neuron disease (FTD-MND). Previous reports have suggested that the functional pattern is similar in FTD and FTD-MND. However, some neuropathological studies suggest greater involvement of medial temporal regions in FTD-MND than in FTD. Using statistical parametric mapping (SPM96), we compared the metabolic patterns obtained at rest with positron emission tomography in 10 FTD patients and three FTD-MND patients with those obtained from 46 healthy subjects (HS). Mean age, duration of illness and dementia stage did not differ statistically between the FTD and FTD-MND groups. In comparison with HS, both groups showed frontal and anterior temporal hypometabolism at P<0.001. When the FTD-MND group was compared to the FTD group, significant hypometabolism was only observed in bilateral amygdala, bilateral hippocampus, and bilateral enthorinal and parahippocampal regions (Brodmann's areas, BA 28/36) at P<0.005. We found no significant differences in regional glucose uptake when FTD patients were contrasted to FTD-MND patients. Our results suggest statistically comparable frontal and lateral temporal hypometabolism in both conditions but greater impairment of medial temporal lobe activity in FTD-MND. Our results and a review of the literature support the hypothesis that there is a functional continuum between classical motor neuron disease (cMND), FTD-MND, and FTD. [less ▲]

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See detailMethodological Issues in a Cost-of-Dementia Study in Belgium: The National Dementia Economic Study (Nades)
Kurz, Xavier; Broers, Mattie; Scuvée-Moreau, Jacqueline ULg et al

in Acta Neurologica Belgica (1999), 99(3), 167-75

The NAtional Dementia Economic Study (NADES) is an on-going prospective, one-year cohort study developed in Belgium to assess the socio-economic consequences of dementia in a group of patients and their ... [more ▼]

The NAtional Dementia Economic Study (NADES) is an on-going prospective, one-year cohort study developed in Belgium to assess the socio-economic consequences of dementia in a group of patients and their caregivers (n = 400). Comparison is made with a group of subjects with cognitive impairment and no dementia (n = 100) and a group of subjects without any cognitive impairment (n = 100). Recruitment of subjects is based on screening of warning signs of dementia by general practitioners, followed by a Cambridge Mental Disorders of the Elderly Examination (CAMDEX) performed at home. This paper presents an overview of the study protocol and the rationale for basic design options, such as the choice of study population, screening strategy, and methods used for the case validation. It also presents preliminary results on the prevalence of dementia in general practice, the sensitivity and specificity of the warning signs as a screening test of dementia, and the validity of a computerised case ascertainment algorithm based on DSM-III-R criteria. [less ▲]

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See detailEarly thalamic and cortical hypometabolism in adult-onset dementia due to metachromatic leukodystrophy
Salmon, Eric ULg; Van der Linden, Martial ULg; Maertens De Noordhout, Alain ULg et al

in Acta Neurologica Belgica (1999), 99(3), 185-188

A case of early-onset adult dementia with family history of dementia is reported, characterised by neuropsychological deficits, suggesting frontal involvement, with mild non specific white matter ... [more ▼]

A case of early-onset adult dementia with family history of dementia is reported, characterised by neuropsychological deficits, suggesting frontal involvement, with mild non specific white matter abnormalities on CT scan. Familial Alzheimer's disease was suspected but the neuropathological diagnosis on brain biopsy was metachromatic leukodystrophy. 18FDG-PET revealed a very peculiar pattern of metabolic impairment in thalamic areas, in medial and frontopolar regions, and in occipital lobes. Neuropsychological follow-up showed relatively stable difficulties of long-term memory and signs of frontal lobe dysfunction, similar to those observed in subcortical dementias. MRI subsequently showed periventricular leukoencephalopathy. The brain metabolic pattern observed in that case of metachromatic leukodystrophy was quite different from that reported in other types of dementia. [less ▲]

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See detailComparison of impaired subcortico-frontal metabolic networks in normal aging, subcortico-frontal dementia, and cortical frontal demential
Garraux, Gaëtan ULg; Salmon, Eric ULg; Degueldre, Christian ULg et al

in Neuroimage (1999), 10(2), 149-162

Normal aging, progressive supranuclear palsy (PSP), and frontotemporal dementia (FTD) are characterized by different degrees of decline in frontal lobe functions. We used (18)FDG-PET and statistical ... [more ▼]

Normal aging, progressive supranuclear palsy (PSP), and frontotemporal dementia (FTD) are characterized by different degrees of decline in frontal lobe functions. We used (18)FDG-PET and statistical parametric mapping (SPM96) to compare relative subcorticofrontal metabolic impairment at rest in 21 healthy elderly subjects (HES), 20 PSP patients, and 6 FTD patients. When HES were compared to 22 healthy young subjects, widespread decrease in metabolism was observed in bilateral medial prefrontal areas including anterior cingulate cortices, in dorsolateral prefrontal areas, in left lateral premotor area, in Broca's area, and in left insula. In PSP compared to the 43 healthy subjects (HS), we observed subcorticofrontal metabolic impairment including both motor and cognitive neural networks. Impairment of functional connections between midbrain tegmentum and cerebellar, temporal and pallidal regions was demonstrated in PSP as compared to HS. When comparing FTD to HS, glucose uptake was primarily reduced in dorsolateral and ventrolateral prefrontal cortices and in frontopolar and anterior cingulate regions. There was also bilateral anterior temporal, right inferior parietal, and bilateral striatal hypometabolism. Finally, FTD showed more severe striatofrontal metabolic impairment than PSP, while mesencephalothalamic involvement was only observed in PSP. Our data suggest that subcorticofrontal metabolic impairment is distributed in distinct subcorticocortical networks in normal aging, PSP, and FTD. Subcorticofrontal dementia in PSP is related to hypometabolism in discrete frontal areas, which are probably disconnected from certain subcortical structures. The concept of subcortical dementia is reinforced by our data, which show disrupted functional connections between mesencephalon and cerebellar cortex, inferior and medial temporal regions, and pallidum. [less ▲]

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See detailImpaired effective cortical connectivity in vegetative state : Preliminary investigation using PET
Laureys, Steven ULg; Goldman, Serge; Phillips, Christophe ULg et al

in Neuroimage (1999), 9(4), 377-382

Vegetative state (VS) is a condition of abolished awareness with persistence of arousal. Awareness is part of consciousness, which itself is thought to represent an emergent property of cerebral neural ... [more ▼]

Vegetative state (VS) is a condition of abolished awareness with persistence of arousal. Awareness is part of consciousness, which itself is thought to represent an emergent property of cerebral neural networks. Our hypothesis was that part of the neural correlate underlying VS is an altered connectivity, especially between the associative cortices. We assessed regional cerebral glucose metabolism (rCMRGlu) and effective cortical connectivity in four patients in VS by means of statistical parametric mapping and [F-18]fluorodeoxyglucose-positron emission tomography. Our data showed a common pattern of impaired rCMRGlu in the prefrontal, premotor, and parietotemporal association areas and posterior cingulate cortex/precuneus in VS. In a next step, we demonstrated that in VS patients various prefrontal and premotor areas have in common that they are less tightly connected with the posterior cingulate cortex than in normal controls. These results provide a strong argument for an alteration of cortical connectivity in VS patients. (C) 1999 Academic Press. [less ▲]

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See detailFunctional neuroanatomy of hypnotic state
Maquet, Pierre ULg; Faymonville, Marie-Elisabeth ULg; Degueldre, Christian ULg et al

in Biological Psychiatry (1999), 45(3), 327-333

BACKGROUND: The aim of the present study was to describe the distribution of regional cerebral blood flow during the hypnotic state (HS) in humans, using positron-emission tomography (PET) and statistical ... [more ▼]

BACKGROUND: The aim of the present study was to describe the distribution of regional cerebral blood flow during the hypnotic state (HS) in humans, using positron-emission tomography (PET) and statistical parametric mapping. METHODS: The hypnotic state relied on revivification of pleasant autobiographical memories and was compared to imaging autobiographical material in "normal alertness." A group of 9 subjects under polygraphic monitoring received six H215O infusions and was scanned in the following order: alert-HS-HS-HS with color hallucination-HS with color hallucination-alert. PET data were analyzed using statistical parametric mapping (SPM95). RESULTS: The group analysis showed that hypnotic state is related to the activation of a widespread, mainly left-sided, set of cortical areas involving occipital, parietal, precentral, premotor, and ventrolateral prefrontal cortices and a few right-sided regions: occipital and anterior cingulate cortices. CONCLUSIONS: The pattern of activation during hypnotic state differs from those induced in normal subjects by the simple evocation of autobiographical memories. It shares many similarities with mental imagery, from which it differs by the relative deactivation of precuneus. [less ▲]

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