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Biomedical subjects

H L Lagrèze

Publications and source records attributed to H L Lagrèze.

11 recordsLinked to original sources
PubMed1998

Chronic progressive leukoencephalopathy in adult celiac disease.

Progressive leukoencephalopathy developed in a patient with adult celiac disease. Neurologic abnormalities appeared 4 years after the gastrointestinal manifestations despite a gluten-free diet and replacement of vitamins. Brain MRI showed marked confluent white matter abnormalities, and stereotactic brain biopsy revealed chronic leukoencephalopathy. Treatment with I.V. steroids and immunoglobulins did not stop disease progression. Celiac disease should be considered in the differential diagnosis of the leukoencephalopathies.

Biopsy↗
PubMed1994

Specific recognition of arteriovenous malformations using Xenon-133 RCBF technique.

With respect to the methodology of the atraumatic Xenon-133 technique the problem whether or not the proposed and introduced arterial artifact (AA) truely represents radiation from intravascular volume and to what extent it affects regional cerebral blood flow (rCBF) calculation is unresolved. We performed rCBF measurements in 22 patients with angiomas to clarify this issue in those patients known to have pathologically enlarged intracranial vessels. P4--the parameter suggested to represent the AA--as well as the conventional blood flow parameter for gray matter (F1) were compared to those of 50 volunteers using four criteria of abnormality: 1. intrahemispheric distribution, 2. interhemispheric differences of homologous detector pairs, 3. differences of mean hemispheric values, 4. visual evaluation of CBF maps. 19 of the 22 patients with angioma fulfilled at least two of the four criteria of abnormality, in comparison to 1 of 50 volunteers. P4's sensitivity for detecting angiomas proved to be higher (86%) than the perfusion parameters of gray matter. Focal increase of P4 proved to be highly specific for the presence of arteriovenous malformation (AVM, specifity 98%). A true arterial artifact exists in most instances in the presence of an AVM. Disregarding AA in the algorithm for calculation rCBF leads to an artificial overestimation of tissue flow in the region of the AVM.

Adult↗
PubMed1993

Functional cortical interaction patterns in visual perception and visuospatial problem solving.

To explore the integration of functional neuronal interactions in human higher cortical functions, we applied multivariate mathematical techniques to regional cerebral blood flow (rCBF) increases induced by mental activity. rCBF was measured using the intravenous xenon-133 clearance technique with 32 bihemispheric detectors in 84 normal volunteers at rest and during both a visuoperceptual accuracy task and a visuospatial problem solving task. Both paradigms activated rCBF in bilateral premotor, motor and postcentral regions. Bilateral prefrontal activation occurred during problem solving but not during the perceptual accuracy task. Partial correlations coefficients and factor analysis identified significant interactions between numerous cortex regions in both tasks. There were highly ordered and integrated patterns of functional interaction patterns between cortex areas subserving elementary subfunctions of complex behavior. Cortical interaction analysis by such techniques is a useful tool to describe the functional anatomy of large-scale neurocognitive networks in the intact human brain. Imaging functional interactions between active cortex areas are complementary to other experimental neurophysiologic methods to explore brain-behavior relationships in health and disease.

Adolescent↗
PubMed1993

Data analysis in behavioral cerebral blood flow activation studies using xenon-133 clearance.

BACKGROUND AND PURPOSE: Three mainstream strategies exist to detect the responses of regional cerebral blood flow to functional activation. We tested the significance of changes in raw regional cerebral blood flow data, regional cerebral blood flow data normalized by division by global cerebral blood flow (dependent model of the regional-to-global cerebral blood flow relation), and regional cerebral blood flow data treating global cerebral blood flow as a covariate (independent model). Both latter models attempt to enhance regional sensitivity by removing global effects. We examined the sensitivity and pitfalls of these three strategies in behavioral activation studies. METHODS: These three strategies of data analysis were applied to changes in regional cerebral blood flow induced by a visuospatial problem-solving task in 38 healthy subjects as measured by the intravenous xenon-133 method with 32 stationary detectors. RESULTS: Mental activation increased blood flow in all regions of interest. Raw data were most sensitive and reliable to detect responses to mental stimulation. Both the independent and dependent models to remove global effects were less sensitive and falsely indicated deactivation in regions that were clearly stimulated. CONCLUSIONS: In behavioral activation paradigms, safe data analysis should be restricted to using raw regional cerebral blood flow increases without normalization or separation of global from regional effects. Studies using complex stimulation tasks should be scrutinized for global cerebral blood flow effects confounding regional responses.

Behavior↗
PubMed1988

Abnormalities of interictal cerebral perfusion in classic but not common migraine.

Regional cerebral blood flow (rCBF) was measured as gray matter blood flow using the 133Xe inhalation technique in 50 pain-free headache patients: Eight patients having classic migraine with normal computed tomograms were matched to patients having common migraine and to normal controls. Interictal rCBF was determined at least 6 days after the last migraine attack and more than 24 hours before the next one. There were no between-group differences for age, PCO2, mean hemispheric blood flow, interindividual and intraindividual variabilities, hyperfrontality, or rCBF symmetry. However, when subjects were classified as to overall abnormal perfusion, a significant number (n = 4, p less than 0.04) of patients with classic migraine had rCBF abnormalities, whereas only one such patient was seen in the group with common migraine. Patients with classic migraine had abnormal mean hemispheric blood flows or disturbed intrahemispheric rCBF patterns. Oligemic and hyperemic regions topographically corresponded to the clinical symptoms in one patient. We conclude that during migraine attacks and interictally there is an instability of rCBF control in patients with classic but not common migraine.

Cerebrovascular Circulation↗
PubMed1988

Delayed immune response in chorea-amyotrophy with spherocytosis.

Progressive CSF lymphocytic pleocytosis and intrathecal IgG-synthesis occurred late in familial amyotrophy, neuropathy, chorea, and dementia with spherocytosis. Immunoblotting showed a serum and CSF antibody apparently directed against glial fibrillary acidic protein. A secondary autoimmune response was probably triggered during the evolution of the neurodegenerative process.

Chorea↗
PubMed1987

Isolated supraclinoid occlusive disease of the internal carotid artery.

Isolated supraclinoid occlusive disease of the internal carotid artery is a rare cause of cerebral ischemia. The authors of the only review of this subject concluded that it is caused predominantly by factors other than atherosclerosis. We examined 6 patients with isolated supraclinoid occlusive lesions. Five of them had one or more risk factors for atherosclerosis. Thus, the isolated stenosis of that part of the internal carotid artery does not seem to represent a particular pathologic entity.

Adult↗
PubMed1987

Quantitative positron emission tomography and single photon emission computed tomography measurements of human cerebral blood flow.

Current methods using emission tomography to quantitate human regional cerebral blood flow (rCBF) are reviewed. The sensitivity and spatial resolution of single photon emission tomography are too low to correlate reliably rCBF with known anatomic landmarks in the brain. However, even if the superior imaging qualities of positron emission tomography are employed, the radiotracers of rCBF frequently do not fully meet the requirements of the models of tracer kinetics that are employed. Therefore, the methodology of reported rCBF studies using emission tomography to measure quantitatively human rCBF needs to be carefully evaluated.

Brain↗
PubMed1986

Effect of flunarizine on regional cerebral blood flow in common and complicated migraine. Pilot study.

Alterations of regional cerebral blood flow (rCBF) are at least epiphenomena of common and complicated migraine, but may lead to serious clinical complications. Since flunarizine seems to be effective in migraine prevention it may exert a beneficial influence on rCBF in migraine as well. rCBF was assessed using the 133Xe inhalation method in 5 patients with common and 8 patients with complicated migraine. Measurements were done interictally prior and after therapy with 15 mg flunarizine p.o. daily over a period of 4 weeks. Major abnormalities of grey matter flow were observed even interictally. Significant improvement of rCBF in initially hypoemic regions may be attributed to flunarizine therapy. These preliminary data suggest that calcium entry blockers may prevent the ischemic complications of migraine.

Brain↗
PubMedDate not supplied

Contralateral flow reduction in unilateral stroke: evidence for transhemispheric diaschisis.

Using clinical presentation, angiography, computed tomography, and nuclear magnetic resonance imaging, 7 patients were identified who had strictly unilateral hemispheric infarction and unilateral cerebrovascular disease. In 6, cerebral blood flow measured by fluorine-18-fluoromethane inhalation and positron emission tomography was reduced in the contralateral hemisphere (p less than 0.05). Multiple regression analysis demonstrated a high correlation between contralateral flow reduction and the degree of flow impairment in the infarcted area (r = 0.941, p = 0.0014) but not with age, risk factor profile, blood pressure, PCO2, hematocrit, or duration of stroke. We conclude that transhemispheric diaschisis best explains the contralateral flow reduction seen in supratentorial ischemic stroke.

Brain↗