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J De Reuck

Publications and source records attributed to J De Reuck.

At least 19 recordsLinked to original sources
PubMed2001

Regional brain activity during different paradigms of mental rotation in healthy volunteers: a positron emission tomography study.

Positron emission tomography (PET) was used to observe changes in regional cerebral blood flow (rCBF) in 10 right-handed healthy volunteers performing two paradigms of mental rotation. In one paradigm, subjects mentally rotated a single alphanumeric stimulus to determine whether it was shown in a normal or mirror-image position. In a second paradigm, subjects mentally rotated and compared pairs of figurative stimuli to determine whether the stimuli were identical or mirror-images. In both paradigms, rCBF was compared with a control task that used identical stimuli, but required no mental rotation. Mental rotation of single alphanumeric stimuli engendered activation in the primary somatomotor area in the left precentral gyrus. Mental rotation of paired figures engendered activation in the left superior parietal lobule and the right frontal medial gyrus. A deactivated area was located in the medial part of the left superior frontal gyrus. Comparison of both paradigms revealed that the left gyrus precentralis was activated significantly during the alphanumeric condition and that the left gyrus lingualis was significantly activated during the paired figures condition. Motor processes may be an inherent part of every mental rotation but the type of motor involvement appears strongly dependent on the specific task or the specific stimuli. Similar paradigms, designed to isolate the same cognitive function, in the same subjects, using the same imaging technology and methodology, but differing only in stimulus material, lead to different areas of neural activation. Task specificity determines the most significant changes in cerebral blood flow in different mental rotation paradigms.

Adult↗
PubMed2001

Parkinsonism in patients with vascular dementia: clinical, computed- and positron emission-tomographic findings.

PURPOSE: The present study investigates the vascular nature of parkinsonian features in patients with 'probable' vascular dementia. PATIENTS AND METHODS: Forty patients with vascular dementia were studied with positron emission tomography (PET) using the steady state technique with (15)O in order to assess regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional metabolic rate for oxygen (rCMRO(2)) in different brain regions. The findings in 10 patients with (VaDP) were compared to 30 without parkinsonism (VaD). RESULTS: The clinical and computed tomographic findings in the parkinsonian patients were similar to those described in the literature as probable vascular parkinsonism. The PET results showed decreased rCBF and rCMRO(2) in the frontal and parietal cortices and in the striatum of the VaDP compared to the VaD group. The decrease of rCBF and rCMRO(2) in frontal and parietal cortices is due to the more severe mental changes in the VaDP group. In the VaDP patients rCBF and rCMRO(2) were more decreased and rOER increased in the striatum contralateral to the most affected parkinsonian side. CONCLUSION: Our PET findings show that local ischemic changes in the striatum contribute to parkinsonism in vascular dementia patients.

Aged↗
PubMed2001

Differential regional cerebral uptake of (18)F-fluoro-2-deoxy-D-glucose in Alzheimer's disease and frontotemporal dementia at initial diagnosis.

In this paper, the cerebral uptake of (18)F-fluoro-2-deoxy-D-glucose (FDG) was studied in a relatively small group of patients suffering from either clinically diagnosed Alzheimer's disease (AD) or frontotemporal dementia during the initial differential diagnostic workup. The image analysis was done visually and semiquantitatively using three different reference regions. Visual analysis confirmed earlier literature findings on the distribution of decreased FDG uptake and demonstrated prevalent asymmetric patterns in both groups. Only semiquantitative analysis using the sensorimotor cortex as a reference region confirmed the visual findings. Moreover, there were no differences in medial temporal lobe activities between both groups, and there was no correlation of medial temporal lobe activity with dementia severity. In the AD group, a correlation of parietal FDG uptake with MMSE scores was found.

Adult↗
PubMed2001

[Vascular dementia].

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Cross-Sectional Studies↗
PubMed2000

Cobalt-55 positron emission tomography in late-onset epileptic seizures after thrombo-embolic middle cerebral artery infarction.

The pathogenesis of late-onset epileptic seizures after thrombo-embolic cerebral infarction is poorly understood. Our previous positron emission tomographic (PET) studies with 15O have demonstrated that post-apoplectic epilepsy is associated with more severe brain ischemia, but we were unable to determine if this was the cause or the consequence of the seizures. Using cobalt-55 (55Co) as PET tracer we can now distinguish recurrent, recent infarction in patients with a previous old infarct in the same vascular territory. In seven out of twelve patients with post-apoplectic seizures an increased uptake of 55Co was observed in the border area and in two of them also within the old infarct core. In the control group, composed of eight seizure-free patients with also an old infarct involving the cortical territory of the middle cerebral artery, no increase in 55Co uptake was observed on PET examination. The present study indicates that in a significant number of patients late-onset epilepsy is the clinical expression of recurrent strokes, occurring in the same vascular territory.

Aged↗
PubMed2000

MRI of the brain in cerebrotendinous xanthomatosis (van Bogaert-Scherer-Epstein disease).

The clinical, biochemical and magnetic resonance imaging findings of two patients with cerebrotendinous xanthomatosis are reported. This is a rare hereditary disease. Early recognition of this entity is important in view of the existing treatment possibilities. Magnetic resonance imaging findings typically include a bilateral and almost symmetrical increase of the signal intensity on the T2-weighted images in the cerebellar and periventricular cerebral white matter, the basal ganglia, the dentate nuclei and the brainstem as well as cerebellar and cerebral atrophy.

Adult↗
PubMed2000

Successful immunoglobulin treatment in a patient with neuromyotonia.

Neuromyotonia is characterized by spontaneous and continuous muscle fibre activity leading to muscle cramps, pseudomyotonia, myokymia and weakness. Electromyographic recordings show typical findings. An auto-immune mechanism has been suggested in at least a subset of patients. Various therapies have been tried with different outcome. A patient with neuromyotonia responding well to high-dose immunoglobulin treatment is presented.

Autoimmunity↗
PubMed2000

Acute single photon emission computed tomographic study of vagus nerve stimulation in refractory epilepsy.

PURPOSE: Left-sided vagus nerve stimulation (VNS) is an efficacious treatment for patients with refractory epilepsy. The precise mechanism of action remains to be elucidated. Only limited data on VNS-induced changes in regional cerebral blood flow (rCBF) are available. The aim of this study was to investigate rCBF changes during initial VNS with single-photon emission computed tomography (SPECT). METHODS: In 12 patients (8 women, 4 men) with mean age of 32 years and mean duration of epilepsy of 19 years, VNS-induced rCBF changes were studied by means of a 99mTc-ethyl cysteinate dimer activation study with a single-day split-dose protocol before and immediately after initial stimulation. Images were acquired on a triple-head camera with fan-beam collimators and were reconstructed with scatter and attenuation correction. After coregistration to a standardized template, both a semiquantitative analysis using predefined volumes-of-interest (VOIs) as well as voxel-by-voxel analysis of the intrasubject activation were performed. During follow-up, efficacy of VNS in terms of seizure-frequency reduction was studied. RESULTS: The semiquantitative analysis, with reference to the total counts in all VOIs, revealed a significant decrease of activity in the left thalamus immediately after the initial stimulation train. These results agreed with voxel-by-voxel analysis. In our study ipsilateral thalamic hypoperfusion was the most significant finding. Mean frequency of complex partial seizures was reduced from 30 per month before implantation to six per month after implantation. CONCLUSIONS: VNS induces rCBF changes immediately after initial stimulation that can be studied with SPECT. VNS-induced changes in the thalamus may play an important role in suppression of seizures. However, no significant relation between the level of hypoperfusion and subsequent clinical efficacy was found.

Adolescent↗
PubMed1999

High-performance liquid chromatographic determination of [11C]1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide in mouse plasma and tissue and in human plasma.

The high-performance liquid chromatographic determination of 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide ([11C]PK 11195) is described. The method was successfully applied for plasma and tissue analysis after i.v. injection of [11C]PK 11195 in mice and for plasma analysis after administration of [11C]PK 11195 to humans. Separation is effected on a RP-C18 column, using a mixture of acetonitrile-water-triethylamine (65:35:0.5, v/v). Quantitative measurements of radioactivity are performed on a one-channel gamma-ray spectrometer equipped with a 2 x 2 in. NaI(Tl) detector. For humans rapid metabolisation of [11C]PK 11195 was observed. At 5, 20 and 35 min post injection 5%, 22% and 32%, respectively, of the plasma activity consisted of at least two more polar metabolites. Despite the extensive metabolisation rate in mice (up to 42% at 10 min post injection of [11C]PK 11195), no 11C-labelled metabolites could be detected in the extracts of brain and heart.

Animals↗
PubMed1999

55Cobalt (Co) as a PET-tracer in stroke, compared with blood flow, oxygen metabolism, blood volume and gadolinium-MRI.

Several studies have shown the feasibility of divalent cobalt (Co)-isotopes (55Co and 57Co) in imaging of neuronal damage in stroke, multiple sclerosis, cerebral tumors and traumatic brain injury. Little is known how regional Co uptake relates to other pathophysiological changes after stroke. Therefore, we compared 55Co-PET with functional parameters such as regional cerebral blood flow (rCBF) using C(15)O(2), regional oxygen metabolism (rCMRO(2)) using 15O(2), regional cerebral blood volume (rCBV) and post-gadolinium (Gd) T(1)w-MRI to assess the permeability of the blood-brain-barrier (BBB). Sixteen patients (10 female; six male) aged 43 to 84 (mean 69) years with first ever stroke, as shown by CT or MRI, were examined with 55Co-PET and C(15)O(2)-, 15O(2)- and C(15)O-PET in one single session, in a period varying from 0 to 30 days after stroke-onset. Regions of infarction on C(15)O(2)- and 15O(2)-PET (defined by rCMRO(2)<65% or rCBF<45% of the contralateral value) were subsequently superimposed on the 55Co-PET scan. Clinical status was established using the Orgogozo stroke scale, which was assessed both at day 1 and at discharge (at least 6 weeks after day 1). Accumulation of 55Co was seen in eight out of 16 patients, occurring in areas showing a diminished oxygen metabolism, was only partially related to blood flow, and was located mainly outside the extent of the infarction or luxury perfusion as seen on post-Gd T(1)w-MRI. Statistical analysis showed a negative correlation between the Orgogozo score at discharge and the uptake of radioactive cobalt.

Adult↗
PubMed1999

Accuracy of single-sequence MRI for investigation of the fluid-filled spaces in the inner ear and cerebellopontine angle.

We prospectively studied 163 patients referred for MRI of the temporal bone. A presumed diagnosis was made using only one of three sequences: a single thick (12 mm) slice fast T2-sequence, 3D fourier transform constructive interference in steady state (3DFT-CISS) sequence and a gadolinium-enhanced T1-weighted sequence. The visibility of the cochlea, vestibule and superior, lateral and posterior semicircular canals of normal temporal bones was assessed on the T2-weighted images: they were almost always visible (98-100%), with exception of the superior semicircular canal, seen in only 35% of cases. The images were interpreted as abnormal in 34 patients (21%). Using only the fast T2-weighted, 3DFT-CISS and gadolinium-enhanced T1-weighted sequences a presumed false positive diagnosis was made in 5, 1 and 0 cases and a false negative diagnosis in 2, 2 and 4 cases respectively. The overall reliability of the thick-section fast T2-weighted images is limited. This study suggests that a combination of gadolinium-enhanced T1-weighted and 3DFT-CISS images can be considered the gold standard for temporal bone MRI and neither sequence performed separately is as accurate as both together.

Adolescent↗
PubMed1999

Vagus nerve stimulation for medically refractory epilepsy; efficacy and cost-benefit analysis.

INTRODUCTION: Vagus nerve stimulation is a novel treatment for patients with medically refractory epilepsy, who are not candidates for conventional epilepsy surgery, or who have had such surgery without optimal outcome. To date only studies with relatively short follow-up are available. In these studies efficacy increased with time and reached a maximum after a period of 6 to 12 months. Implantation of a vagus nerve stimulator requires an important financial investment but a cost-benefit analysis has not been published. PATIENTS AND METHODS: Our own experience with VNS in Gent comprises 15 patients with mean age of 29 years (range: 17-44 years) and mean duration of epilepsy of 18 years (range: 4-32 years). All patients underwent a comprehensive presurgical evaluation and were found not to be suitable candidates for resective epilepsy surgery. Mean post-implantation follow-up is 24 months (range: 7-43 months). In patients with follow-up of at least one year, efficacy of treatment in terms of seizure control and seizure severity was assessed one year before and after the implantation of a vagus nerve stimulator. Epilepsy-related direct medical costs (ERDMC) before and after the implantation were also compared. RESULTS: A mean reduction of seizure frequency from 14 seizures/month (range: 2-40/month) to 8 seizures/month (range: 0-30/month) was achieved (Wilcoxon signed rank test n = 14; p = 0.0016). Five patients showed a marked seizure reduction of > or = 50%; 6 became free of complex partial seizures, 3 of whom became entirely seizure free for more than 12 months; 2 patients had a worthwhile reduction of seizure frequency between 30-50%; in 2 patients seizure frequency reduction has remained practically unchanged. Seizure freedom or > or = 50% seizure reduction was achieved within the first 4 months after implantation in 6/11 patients. Before the implantation, the mean yearly epilepsy-related direct medical costs per patient were estimated to be 8830 US$ (n = 13; range: 1879-31,129 US$; sd = 7667); the average number of hospital admission days per year was 21 (range: 4-100; sd = 25.7). In the 12 months after implantation, ERDMC had decreased to 4215 US$ (range: 615-11,794 US$; sd = 3558) (Wilcoxon signed rank test n = 13; p = 0.018) and the average number of admission days to 8 (range: 0-35) (Wilcoxon signed rank test n = 13; p = 0.023). CONCLUSION: VNS is an effective treatment of refractory epilepsy and remains effective during long-term follow-up. Cost-benefit analysis suggests that the cost of VNS is saved within two years following implantation.

Adolescent↗
PubMed1999

Cobalt-55 positron emission tomography in recurrent ischaemic stroke.

The present study investigates if Cobalt-55 (55Co) positron emission tomography (PET) allows us to distinguish and detect recent, recurrent strokes in patients who had already suffered a previous infarct in the same vascular territory. Fourteen patients with recurrent strokes underwent a 55Co PET scan of the brain. Recently infarcted areas, less than 2 months old, had a high 55Co uptake ratio, whereas infarcts of 6 months to 1 year had an uptake ratio comparable to normal brain tissue. In infarcts older than 2 years the 55Co uptake ratio was decreased compared to the control values. The evolution in 55Co uptake ratios with time can be explained by the dynamics of the inflammatory response within the infarct core. 55Co PET allows to demonstrate stroke recurrence and suggests that single photon emission tomography, using 57Co as the tracer, could be a more easy alternative to be used in routine neurological practice.

Adult↗
PubMed1999

Long-term results of vagus nerve stimulation in refractory epilepsy.

Vagus nerve stimulation (VNS) is an adjunctive antiepileptic treatment for patients with refractory epilepsy. Limited information on long-term treatment with VNS is available. The purpose of this paper is to present our experience with VNS with a follow-up of up to 4 years. Twenty-five patients (13 females and 12 males) with refractory partial epilepsy were treated with VNS. The first 15 patients with a mean age of 30 years and a mean duration of epilepsy of 17.5 years have sufficient follow-up for analysis. Mean post-implantation follow-up was 29 months and mean stimulation output 2.25 mA. There was a mean seizure frequency reduction from 14 complex partial seizures (CPS) per month before implantation to 8 CPS per month after implantation (P = 0.0016; Wilcoxon signed-rank rest (WSRT)). The mean maximum CPS-free interval changed from 9 to 312 days (P = 0.0007; WSRT). Six patients were free of CPS for at least one year. In one patient, one antiepileptic drug (AED) was tapered; in 10 patients, AEDs remained unchanged; in four, one adjunctive AED was administered. Side effects occurred in six patients, three of whom required a temporary reduction of output current. Nine patients reported no side effects at all. Treatment with VNS remains effective in the long-term. In this series 4 / 15 (27%) patients with highly refractory epilepsy experienced entirely seizure-free intervals of 12 months or more.

Adolescent↗
PubMed1999

The clinical safety of high-dose piracetam--its use in the treatment of acute stroke.

Recent post-marketing surveillance reports have confirmed the benign safety profile and lack of organ toxicity shown by piracetam during its 25 years of clinical usage. Tolerance has proved equally good with the more recent use of larger doses (up to 24 g/day) for the long-term control of cortical myoclonus and when given intravenously to patients with acute stroke. This paper provides a brief review of these findings and records the safety of piracetam as found in the Piracetam in Acute Stroke Study (PASS), a randomized multicenter placebo-controlled study in 927 patients with acute ischemic stroke. Patients receive one intravenous bolus injection of placebo or 12 g piracetam, piracetam 12 g daily for 4 weeks and maintenance treatment for 8 weeks. The major results have been reported (De Deyn et al., Stroke 28 [1997] 2347-2352). Safety was assessed taking into account adverse events including abnormal laboratory test results and mortality. Death within 12 weeks occurred more frequently in the piracetam group but the difference from placebo was not significant. Of many potential risk, prognostic and treatment-related factors examined by logistic regression, 6 contributed significantly to death of which the most important were initial severity of stroke and age. Neither treatment nor any treatment-related factor contributed significantly to death. Adverse events were similar in frequency, type and severity in piracetam and placebo groups. Events of cerebral, non-cerebral and uncertain origin likewise occurred with similar frequency. Few patients discontinued because of adverse events. There was no difference between treatments in the frequency of events associated with bleeding, including hemorrhagic transformation of infarction. An important finding was that, of 31 patients with primary hemorrhagic stroke enrolled, 3 piracetam-treated patients died compared with 6 on placebo. The results suggest that piracetam in high dosage may be given to patients with acute stroke without significant adverse effects.

Acute Disease↗
PubMed1999

Acetazolamide vasoreactivity in vascular dementia: a positron emission tomographic study.

The present study investigates the vasoreactivity of the brain in patients with large infarcts and dementia (multi-infarct dementia; MID) and in patients with microangiopathy, lacunes, white matter changes and dementia (lacunar dementia; LD) using positron emission tomography (PET) and 13NH3 as regional cerebral blood flow (rCBF) tracer. In the control group, an increase in rCBF ranging from 32 to 43% was found in all brain regions after intravenous acetazolamide administration. In both the MID group and the group with multiple infarcts without dementia, moderate loss of vasoreactivity was observed in the frontal, temporal and parietal cortex compared to the control values. Vasoreactivity was severely impaired in all cerebral regions of the LD group and restricted to the thalamus in the group with lacunes and white matter changes without dementia (lacunar stroke; LS). This suggests that global loss of vasoreactivity is not a determining factor in the occurrence of MID, but might be important in LD. The present study shows that loss of the vascular reserve leading to exhausted metabolic reserve of the whole brain is one of the possible mechanisms for the occurrence of vascular dementia.

Acetazolamide↗
PubMed1999

White matter changes in stroke patients. Relationship with stroke subtype and outcome.

White matter changes (WMC), detected by imaging techniques, are frequent in stroke patients. The aim of the study was to determine how WMC relate to stroke subtypes and to stroke outcome. We made a systematic Medline search for articles appearing with two of the following key words: either 'WMC or white matter lesions or leukoencephalopathy or leukoaraiosis' and 'stroke or cerebral infarct or cerebral hemorrhage or cerebrovascular disease or transient ischemic attack (TIA)'. WMC, as defined radiologically, are present in up to 44% of patients with stroke or TIA and in 50% of patients with vascular dementia. WMC are more frequent in patients with lacunar infarcts, deep intracerebral hemorrhages, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and cerebral amyloid angiopathy. After an acute ischemic stroke, WMC are associated with a higher risk of death or dependency, recurrent stroke of any type, cerebral bleeding under anticoagulation, myocardial infarction, and poststroke dementia. WMC in stroke patients are often associated with small-vessel disease and lead to a higher risk of death, and poor cardiac and neurological outcome. However, several questions remain open and need further investigations.

Age Factors↗