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Biomedical subjects

J C Froment

Publications and source records attributed to J C Froment.

At least 37 records · Page 2Linked to original sources
PubMed2000

Intravenous tPA in acute ischemic stroke related to internal carotid artery dissection.

The authors describe the outcomes in 11 patients who had acute ischemic stroke related to internal carotid artery (ICA) dissection and were treated with IV tissue plasminogen activator (tPA). One symptomatic intracerebral hemorrhage occurred 36 hours after tPA was given. The mean day 90 modified Rankin Scale (m-RS) score was 2.4 (+/-1.6). No death was observed at 3 months. Four patients of 11 (36.4%) made an excellent recovery (day 90 m-RS score: 0 to 1). This study demonstrates the feasibility of IV thrombolysis with tPA (0.8 mg/kg) in ischemic stroke related to ICA dissection within the first 7 hours.

Adult↗
PubMed2000

rtPA intravenous thrombolysis in anterior choroidal artery territory stroke.

OBJECTIVE: To study the possible specific response to recombinant tissue plasminogen activator (rtPA) thrombolysis of anterior choroidal artery (AChA) stroke. BACKGROUND: Outcome and response after rtPA thrombolysis are possibly better in small-vessel infarcts, but a specific study of AChA stroke has not yet been performed. METHODS: The authors proposed an open trial of IV rtPA within 7 hours in patients age 20 and 81 years with all types of internal carotid artery territory stroke if the baseline Scandinavian Stroke Scale (SSS) score was less than 48. A dose of rtPA 0.8 mg/kg was infused over 90 minutes. Of 114 consecutive patients, 9 patients (7.9%) exhibited hypodensity in the AChA territory on day 1 brain CT. RESULTS: Seven of nine patients with AChA infarct had a primary early recovery within 6 hours after the initiation of rtPA infusion. In addition, recovery was complete in five patients and partial in two patients. No intracerebral hematoma was observed. Three patients had a "reinfarct syndrome" at 12, 25, and 48 hours respectively. However, in the two latter patients treated with IV heparin, the deficit disappeared again with the increase of heparin dose in one patient and disappeared spontaneously in the other patient. The overall outcome at day 90 was six total recoveries in nine patients (66%). Patients with a final good outcome had a slight "unstructured" hypodensity in the AChA territory on day 1 brain CT, whereas patients with a bad outcome had the classic "structured" hypodensity of AChA territory stroke. CONCLUSION: These data support a specific quick response of AChA territory stroke to IV rtPA thrombolysis, probably due to the small size of the artery and of the "clot." The high frequency of the reinfarct syndrome is a clinical fact that is difficult to explain. Efficient heparin treatment after 24 hours may control the reinfarct syndrome in some patients.

Aged↗
PubMed2000

Vasodilatory response of border zones to acetazolamide before and after endarterectomy : an echo planar imaging-dynamic susceptibility contrast-enhanced MRI study in patients with high-grade unilateral internal carotid artery stenosis.

BACKGROUND AND PURPOSE: The importance of hemodynamic changes related to a high-grade internal carotid artery (ICA) stenosis remains a matter of controversy. Areas between the vascular territories of major cerebral arteries, namely, the border zones, may be selectively vulnerable to hemodynamic alteration. The aim of this study was to search for any hemodynamic impact of carotid endarterectomy (CEA) on vasodilatory response, in particular, within the border zones, by means of multislice dynamic susceptibility contrast MRI. METHODS: Thirteen patients with a high-grade unilateral ICA stenosis (>80%) were examined. Relative regional cerebral blood volume (rrCBV) was determined separately for white matter, gray matter, and anterior and posterior border zones by the acetazolamide test. A vasomotor reactivity index was evaluated from the rrCBV values. Values from the ipsilateral hemisphere were compared with contralateral ones, before and after CEA. RESULTS: Before CEA, rrCBV values in the anterior border zones were significantly (P<0.05) higher in the ipsilateral hemisphere than in the contralateral hemisphere. A decrease in vasomotor reactivity indexes was also observed in the lesion side, but the difference from the contralateral side was not statistically significant. In posterior border zones, no differences in rrCBV or vasomotor reactivity were found between the ipsilateral and the contralateral hemispheres. After CEA, the rrCBV asymmetry in the anterior border zones cleared. CONCLUSIONS: High-grade ICA stenosis with efficient primary collateral pathways may have an early limited hemodynamic impact within border-zone areas. The favorable course of these abnormalities after surgery suggests an additional benefit of CEA at this stage.

Acetazolamide↗
PubMed2000

Accuracy of three-dimensional gadolinium-enhanced MR angiography in the assessment of extracranial carotid artery disease.

OBJECTIVE: The purpose of this study was to assess three-dimensional (3D) gadolinium-enhanced MR angiography, used alone or in association with duplex Doppler sonography, with a fast acquisition time (8 sec) for evaluating the extracranial carotid arteries. SUBJECTS AND METHODS: In this prospective study, 48 successive patients with carotid artery stenoses were examined with 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography. Of the 44 eligible patients, conventional angiography was available in 33 and duplex sonography in 27. We used the North American Symptomatic Carotid Endarterectomy Trial technique to quantify stenosis on all angiograms, and a 250 cm/sec threshold at duplex sonography to diagnose stenoses greater than 70%. Image quality of 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography was assessed, as well as sensitivity and specificity for each technique alone and in combination with duplex sonography. Conventional angiography was the gold standard. RESULTS: Three-dimensional gadolinium-enhanced MR angiography yielded good image quality in 90% of cases. When used alone, it yielded a sensitivity and a specificity of 94% and 85%, respectively, in screening stenoses greater than 70% (70-99%). When combined with duplex Doppler sonography, it provided a 100% sensitivity and specificity for detection of stenoses between 70% and 99% and would have obviated 61% of conventional angiography. In comparison, 3D time-of-flight MR angiography used alone yielded a sensitivity of 88% and a specificity of 94%. In combination with duplex Doppler sonography, its use would have obviated conventional angiography in 74% of cases. Three-dimensional gadolinium-enhanced MR angiography provided accurate results in the diagnosis of occlusions and ulcers and can visualize distant stenoses. CONCLUSION: Used alone, 3D gadolinium-enhanced MR angiography is not accurate enough to replace conventional angiography in the evaluation of extracranial carotid arteries. In association with duplex Doppler sonography, however, it is accurate and may obviate a significant number of conventional angiographic examinations.

Adult↗
PubMed2000

[Spiral CT evaluation of the craniosynostoses].

Craniosynostoses are defined as the premature closure of one or more sutures of the cranial bones. The resulting craniofacial deformities may be associated with neurologic complications owing to the disproportion between the growing brain and the limited content of the intracranial cavity. Plain skull radiographs are often contributive to the diagnosis. However, they may not be sufficient to detect early cases and to properly evaluate the more complex cases. Computed tomography has been proved to be more efficient in the pretherapeutic evaluation. The authors present here their results in the spiral computed tomographic evaluation of primary and syndromic craniosynostosis, based on a prospective series of 26 patients. The radiologic findings are presented. They have been found here to be similar to those previously described on sequential acquisitions. Spiral computed tomography was found to provide better information than did plain radiographs in 5 cases. The value of the helical acquisition as well as tridimensional reconstructions are discussed.

Child, Preschool↗
PubMed1999

The relation of putamen and caudate nucleus 18F-Dopa uptake to motor and cognitive performances in Parkinson's disease.

The contribution of striatal (caudate nucleus-putamen) dopaminergic deficiency to the severity of motor signs is well established in Parkinson's disease (PD), while its role in the occurrence of cognitive and mood changes remains unresolved. We therefore measured in 27 non-demented PD patients and 10 age-matched controls striatal uptake of [18F]-6-fluoro-L-Dopa (F-Dopa) with PET, and mood (Beck depression), memory (Grober-Buschke), frontal executive functions (verbal fluency and Wisconsin card sorting), and attentional processing of sensory stimuli (N2-P3 auditory event-related potentials--ERPs). Locomotor disability of patients was assessed by Hoehn and Yahr score and Unified Parkinson's Disease Rating Scale (UPDRS). ANOVA showed that memory, but neither frontal lobe functions nor ERPs, was significantly altered in PD patients, whereas indices of depression were found only in advanced PD. The F-Dopa rate constant Ki was significantly reduced in the striatum, more in putamen than caudate nucleus, and inversely correlated with disease duration. A significant inverse correlation was found between both putamen and caudate nucleus Ki and Hoehn and Yahr score, and between putamen--but not caudate nucleus Ki --and UPDRS motor score. Principal components analysis (PCA) of PD patients Ki values and mood, cognitive and ERP parameters gave a three-factor solution. Variables contributing to factor 1 were memory score and N2-P3 ERP latencies, those to factor 2 were striatal Ki values, and those to factor 3 frontal executive performances. Depression did not segregate with any variable. Our findings suggest that unlike locomotor disability, cognitive abilities and mood state of non-demented PD patients are for the most part unrelated to striatal dopaminergic depletion and may result from dysfunction of extra-striatal dopaminergic or from non-dopaminergic systems.

Adult↗
PubMed1999

Simplified projection of EEG dipole sources onto human brain anatomy.

This study was aimed at determining an easy way to project dipole modelling results onto brain anatomy. This simplified projection is based on the estimation of the mean location of the centre of the dipole sphere according to internal brain landmarks. The mean values for the centre location were calculated from ten epileptic patients. To define the axes of the dipole model frame on the patient's magnetic resonance image (MRI), markers were pasted at some electrode positions during the acquisition. An estimation was then made of the mean position of the model centre from the bicommissural line (anterior commissure-posterior commissure [AC-PC]), and a simple transformation to pass from the model cartesian coordinates to the anatomical correlates either in the subject MRI or in the Talairach atlas. These data were then tested in four additional subjects in whom no markers had been placed during the MRI acquisition. On average, the horizontal plane of the sphere model was pitched up 1.9 degrees +/- 1.8 only with respect to the AC-PC horizontal plane, which allowed the projection of dipoles directly onto the Talairach atlas, without pitch. The mean sphere centre was located 7.4 +/- 4.2 mm above the bicommissural line, and 8.2 +/- 1 mm in front of the posterior commissure. In the four additional subjects, projections on MRI and atlas indicated the same anatomical regions and showed high congruence with the physiology or the pathology. This simplified way we report herein has proved to give reliable results. We believe that this method will be useful as a first approximation to project dipole coordinated onto MRI data; moreover, when MRI is unavailable, our results show that dipole modelling results can be superimposed onto atlas slices provided that they are represented according to the AC-PC plane.

Brain↗
PubMed1999

Functional anatomy of perceptual and semantic processing for odors.

The functional anatomy of perceptual and semantic processings for odors was studied using positron emission tomography (PET). The first experiment was a pretest in which 71 normal subjects were asked to rate 185 odorants in terms of intensity, familiarity, hedonicity, and comestibility and to name the odorants. This pretest was necessary to select the most appropriate stimuli for the different cognitive tasks of the second experiment. The second one was a PET experiment in which 15 normal subjects were scanned using the water bolus method to measure regional cerebral blood flow (rCBF) during the performance in three conditions. In the first (perceptual) condition, subjects were asked to judge whether an odor was familiar or not. In the second (semantic) condition, subjects had to decide whether an odor corresponded to a comestible item or not. In the third (detection) condition, subjects had to judge whether the perceived stimulus was made of an odor or was just air. It was hypothetized that the three tasks were hierarchically organized from a superficial detection level to a deep semantic level. Odorants were presented with an air-flow olfactometer, which allowed the stimulations to be synchronized with breathing. Subtraction of activation images obtained between familiarity and control judgments revealed that familiarity judgments were mainly associated with the activity of the right orbito-frontal area, the subcallosal gyrus, the left inferior frontal gyrus, the left superior frontal gyrus, and the anterior cingulate (Brodmann's areas 11, 25, 47, 9, and 32, respectively). The comestibility minus familiarity comparison showed that comestibility judgments selectively activated the primary visual areas. In contrast, a decrease in rCBF was observed in these same visual areas for familiarity judgments and in the orbito-frontal area for comestibility judgments. These results suggest that orbito-frontal and visual regions interact in odor processing in a complementary way, depending on the task requirements.

Adult↗
PubMed1999

[Cortical thrombophlebitis and developmental venous anomalies].

Abnormal intracranial venous drainage called cerebral venous angioma is usually asymptomatic. Hemorrhages and seizures may however occur. The malformation may rarely be revealed by thrombosis. We report the case of a 25-year-old right-handed woman who developed cortical thrombophlebitis subsequent to developmental venous anomalies. After a course of anticoagulant therapy, outcome was good, demonstrating that anticoagulant therapy may be indicated in spite of the high risk of hemorrhage.

Adult↗
PubMed1998

Effects of thalamic hemorrhage on cortical hemodynamic parameters assessed by perfusion MR imaging: preliminary report.

Thalamic lesions may induce a diffuse hypometabolism and subsequent decrease of cortical cerebral blood flow (rCBF) and cerebral blood volume (rCBV). Up to now PET was used to assess these changes. However this latter method cannot be applied routinely to stroke patients because it is expensive and not currently available. The purpose of this preliminary study was to evaluate the effects of 'pure metabolic depression' induced by thalamic stroke on rCBV and rCBF by using a non invasive method perfusion-MRI. Two patients experienced aphasia, with motor and sensory impairment related to thalamic hemorrhage. Four weeks later, dynamic T2*-weighted echo planar imaging was used to produce perfusion-MR images during an intravenous bolus injection of gadopentetate dimeglumine. A decrease of cortical rCBV and rCBF mainly confined to sensorimotor cortex was observed in both cases ipsilateral to the lesion. Although a sequential assessment of this abnormalities is needed in a larger series of patients in order to establish relevant correlations with neurological status, this preliminary study indicates that perfusion-MRI might be a practical and promising tool in the assessment of cortical rCBV and rCBF changes.

Cerebral Cortex↗
PubMed1998

Can cerebrovascular reactivity be assessed by dynamic susceptibility contrast-enhanced MRI?

The acetazolamide (ACZ) test is performed to evaluate the decrease in cerebral perfusion pressure (CPP) by investigation of vasomotor reactivity (VMR). Our aim was to study cerebral blood flow and blood volume changes induced by the ACZ test in healthy control subjects using dynamic susceptibility contrast-enhanced gradient-echo MRI (DSC-MRI). A FLASH sequence was used to produce susceptibility-weighted images during an intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine (Gd-DTPA). After the first dynamic study, 1 g acetazolamide was given intravenously and 10 min later a second bolus of Gd-DTPA was injected. Using the indicator-dilution theory, relative cerebral blood volume and relative cerebral blood flow were estimated. In healthy subjects the ACZ test induced a significant increase in relative blood volume (from 80.5 +/- 10.7 to 113.4 +/- 11.9) and relative blood flow (from 5.73 +/- 0.96 to 7.5 +/- 0.97), symmetrically in the cerebral hemispheres. This approach might be promising in the understanding of cerebral haemodynamics in patients with vascular disorders.

Acetazolamide↗
PubMed1998

Clinical utility of flumazenil-PET versus [18F]fluorodeoxyglucose-PET and MRI in refractory partial epilepsy. A prospective study in 100 patients.

We assessed the clinical utility of [11C]flumazenil-PET (FMZ-PET) prospectively in 100 epileptic patients undergoing a pre-surgical evaluation, and defined the specific contribution of this neuro-imaging technique with respect to those of MRI and [18F]fluorodeoxyglucose-PET (FDG-PET). All patients benefited from a long term video-EEG monitoring, whereas an intracranial EEG investigation was performed in 40 cases. Most of our patients (73%) demonstrated a FMZ-PET abnormality; this hit rate was significantly higher in temporal lobe epilepsy (94%) than in other types of epilepsy (50%) (P < 0.001). Most FMZ-PET findings coexisted with a MRI abnormality (81%), including hippocampal atrophy (35%) and focal hypometabolism on FDG-PET (89%). The area of decreased FMZ binding was often smaller than that of glucose hypometabolism (48%) or larger than that of the MRI abnormality (28%). FMZ-PET did not prove superior to FDG-PET in assessing the extent of the ictal onset zone, as defined by intracranial EEG recordings. However, it provided useful data which were complementary to those of MRI and FDG-PET in three situations: (i) in temporal lobe epilepsy associated with MRI signs of hippocampal sclerosis, FMZ-PET abnormalities delineated the site of seizure onset precisely, whenever they were coextensive with FDG-PET abnormalities; (ii) in bi-temporal epilepsy, FMZ-PET helped to confirm the bilateral origin of seizures by showing a specific pattern of decreased FMZ binding in both temporal lobes in 33% of cases; (iii) in patients with a unilateral cryptogenic frontal lobe epilepsy, FMZ-PET provided further evidence of the side and site of seizure onset in 55% of cases. Thus, FMZ-PET deserves to be included in the pre-surgical evaluation of these specific categories of epileptic patients, representing approximately half of the population considered for epilepsy surgery.

Brain↗
PubMed1998

Allodynia after lateral-medullary (Wallenberg) infarct. A PET study.

We used PET to study regional cerebral blood flow (rCBF) changes in nine patients with unilateral central pain after a lateral medullary infarct (Wallenberg's syndrome). All patients presented, on the abnormal side, a combination of hypaesthesia to noxious and thermal stimuli and allodynia to rubbing of the skin with a cold object (i.e. abnormal pain to innocuous stimulation). The rCBF responses during allodynia were compared with those obtained during stimulation of the normal side using (i) a cold non-noxious stimulus identical to that applied to the painful side, and (ii) an electrical high-frequency stimulus at painful ranges. Statistical analysis disclosed two abnormal patterns of rCBF change during allodynia. First, there is a quantitative change whereby the blood flow response was out of proportion with the actual intensity of the stimulus, i.e. the pattern of activation by innocuous rubbing of the skin was in our patients identical to that previously reported in response to painful stimuli in normal subjects. This pattern concerned primarily the contralateral thalamus in its lateral half and the primary and somatosensory areas, as well as inferior parietal [Brodmann area (BA) 39/40], anterior insular (BA 6) and medial prefrontal (BA 10) cortices. Thalamic over-activity may reflect abnormal transduction and amplification of sensory inputs after spinothalamic deafferentation. This might be responsible for both increased rCBF in multiple cortical targets and the perceived shift of stimulus intensity from innocuous to painful ranges. The second abnormality associated with allodynic sensation was qualitative. It concerned exclusively the contralateral cingulate gyrus, which did not exhibit the usual pain-related rCBF increase reported in normal subjects. This abnormal cingulate response may account for the peculiar response of lateral medullary infarct patients to allodynic pain, which is not simply perceived as an exaggerated pain sensation, but as a new, strange and extremely unpleasant feeling, not previously experienced by the patients.

Adult↗
PubMed1998

Thrombolysis with intravenous rtPA in a series of 100 cases of acute carotid territory stroke: determination of etiological, topographic, and radiological outcome factors.

BACKGROUND AND PURPOSE: Although new, large, double-blind, randomized studies are needed to establish the efficiency of intravenous thrombolysis, open trials of sufficient size may also provide novel data concerning specific outcomes after thrombolysis. METHODS: An open study of intravenous rtPA in 100 patients with internal carotid artery (ICA) territory strokes between 20 and 81 years of age, with a baseline Scandinavian Stroke Scale (SSS) score of <48 at entry was conducted. Inclusion time was within 7 hours after stroke onset. rtPA (0.8 mg/kg) was infused for 90 minutes, with an initial 10% bolus. Heparin was given according to 3 consecutive protocols. The SSS evaluation was done on days 0, 1, 7, 30, and 90. CT scan was performed before treatment, on days 1 and 7. Etiological investigations included echocardiography and carotid Doppler sonography and/or angiography. Outcome at 1 year was documented by SSS score, the modified Rankin Scale (mRS) score, and a 10-point invalidity scale. Multivariate logistic regression was used to identify predictors of poor versus good outcome. RESULTS: At day 90, 45 patients (45%) had a good result, defined as complete regression or slight neurological sequelae (mRS score of 0-1), 18 patients had a moderate outcome (mRS 2-3), and 31 patients had serious neurological sequelae (mRS 4-5). Six patients died, 2 with intracerebral hematoma after immediate heparin. Five of 11 patients (45.5%) treated between 6 and 7 hours had a good result. The overall intracerebral hematoma rate was 7%. Higher values of fibrin degradation products at 2 hours were observed in the subgroup with intracerebral hematomas. Significant predictors of poor outcome on multivariate logistic regression analysis were baseline SSS score of <15 (odds ratio [OR], 3.38; 95% confidence interval [CI], 1.07 to 10. 74; P=0.04), indistinction between white and gray matter on CT scan (OR, 6.59; 95% CI, 2.19 to 19.79; P=0.0008), and proximal internal carotid thrombosis (OR, 3.29; 95% CI, 0.99 to 10.95; P=0.05). CONCLUSIONS: Our study confirms the safety of intravenous rtPA at a dose of 0.8 mg/kg and suggests efficacy for this drug even within 7 hours. Outcome and hematoma rates were at least as favorable as for trials of therapy with a 3-hour time window. Subgroups with a poor prognosis include low baseline neurological score, baseline CT changes, and proximal ICA thrombosis. However, approximately 30% of patients with each of these characteristics show a good outcome, so their inclusion in future routine rtPA protocols is still justified.

Adult↗
PubMed1997

Neurofilament architecture of superior and mesial premotor cortex in the human brain.

Monoclonal antibody (SMI-32) to neurofilament protein was used in an immunochemical study of the premotor cortex of two human brains in comparison with other architectonic techniques such as Nissi, myelin, cytochrome-oxidase and acetylcholinesterase staining in order to distinguish cortical subdivisions. SMI-32 immunoreactivity technique provides 'neurofilament architecture' patterns specific to area 4, caudal area 6 (area 6c) and rostral area 6 (area 6r). Particularly, the distinction between the two subdivisions of area 6, which is difficult to appreciate with the usual cytochemical or enzyme architectonic techniques, appears very apparent with this technique. Hence, it was possible to localize the topographic boundaries of area 6a alpha and 6a beta of the Vogts on the dorso-lateral convexity and the supplementary motor area and the presupplementary motor area on the mexial wall of the hemisphere.

Adult↗
PubMed1997

Matching of digitised brain atlas to magnetic resonance images.

A method has been developed to match a standard digitised brain atlas onto MR images for identification of cerebral structures in anatomical images. This method uses, first, a three-dimensional crude registration based on the proportional system of Talairach. Then, a two-dimensional refined registration is performed using a deformation function based on a set of homologous landmarks on both images (MR and atlas). Displacements vectors are computed between each corresponding landmark. These vectors are interpolated by thin-plate splines, generating an unwarping function defined on the whole image. This function can then be applied on any structure of the atlas. An evaluation of the matching procedure has been performed. First, the influence of the choice of the landmarks has been evaluated for the fine registration method. The latter has been then compared to the crude registration method considered as a classical reference method. These results show the advantages of the fine registration approach.

Algorithms↗