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Biomedical subjects

J C Froment

Publications and source records attributed to J C Froment.

At least 73 records · Page 4Linked to original sources
PubMed1994

Striatocapsular infarction: MRI and MR angiography.

We present a case of left striatocapsular infarction manifest clinically as a transient right hemiparesis. MRI showed a left striatocapsular infarct. Striatocapsular infarction, unlike lacunar infarction, is often associated with occlusive disease of the carotid artery. In order to screen the carotid vessels, cervical MR angiography (MRA) was performed during the same examination, demonstrating a left internal carotid artery occlusion, confirmed by contrast arteriography. MRA, a noninvasive modality, can be a useful adjunct to MRI, when diagnostic information concerning the cervical carotid artery is needed.

Adult↗
PubMed1994

Dissociation of temporal and frontal components in the human auditory N1 wave: a scalp current density and dipole model analysis.

This study reports a combined scalp current density (SCD) and dipole model analysis of the N1 wave of the auditory event-related potentials evoked by 1 kHz tone bursts delivered every second. The SCD distributions revealed: (i) a sink and a source of current reversing in polarity at the inferotemporal level of each hemiscalp, compatible with neural generators in and around the supratemporal plane of the auditory cortex, as previously reported; and (ii) bilateral current sinks over frontal areas. Consistently, dynamic dipole model analysis showed that generators in and outside the auditory cortex are necessary to account for the observed current fields between 65 and 140 msec post stimulus. The frontal currents could originate from the motor cortex, the supplementary motor area and/or the cingulate gyrus. The dissociation of an exogenous, obligatory frontal component from the sensory-specific response in the auditory N1 suggests that parallel processes served by distinct neural systems are activated during acoustic stimulation. Implications for recent models of auditory processing are discussed.

Adult↗
PubMed1994

Effects of GABAA receptors activation on brain glucose metabolism in normal subjects and temporal lobe epilepsy (TLE) patients. A positron emission tomography (PET) study. Part I: Brain glucose metabolism is increased after GABAA receptors activation.

Though gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the human central nervous system, the metabolic response to GABA system activation remains imperfectly known. We studied in vivo with positron emission tomography (PET) the variations of glucose metabolism in the human brain after stimulation of the GABAA receptors by systemic administration of the specific GABAA agonist, 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP). These investigations were performed in three normal volunteers and as part of presurgical evaluation for temporal lobe epilepsy in six patients. While clinical and electroencephalographic (EEG) monitoring showed a sedative effect and sleepiness after THIP administration, glucose metabolism was paradoxically increased in grey matter structures, which are known to have a high density of GABAA receptors. These findings suggest that the pharmacological activation of GABA pathways, although inhibitory and producing a decrease of vigilance, increases the energetic demand at least during a phase of GABA agonist action, probably at the synaptic or at the glial cell level.

Adult↗
PubMed1994

Effects of GABAA receptors activation on brain glucose metabolism in normal subjects and temporal lobe epilepsy (TLE) patients. A positron emission tomography (PET) study. Part II: The focal hypometabolism is reactive to GABAA agonist administration in TLE.

Positron emission tomography (PET) using [18F]fluorodeoxyglucose (FDG) was used to study the metabolic response of focal hypometabolism to the administration of a specific GABAA agonist (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), THIP, in six temporal lobe epilepsy (TLE) patients. After THIP injection, the increase of glucose metabolism in the hypometabolic focus was larger than the mean increase reported in the whole brain (Part I; Epilepsy Res., 19 (1994) 45-54). Within the hypometabolic focus, this increase was significantly higher in regions with the lowest basal metabolic level. This metabolic response in the hypometabolic focus, observed in the absence of any epileptic discharge during FDG accumulation and PET data acquisition, suggests that GABAA receptors are up-regulated or, at least, preserved in TLE.

Adult↗
PubMed1993

Pontine versus capsular pure motor hemiparesis.

We prospectively studied 21 patients with pure motor hemiparesis (PMH). CT showed a capsular lesion consistent with the clinical syndrome in 15 patients (71%) and was repeatedly negative in the remaining six (29%). In all six patients with repeatedly negative CT, MRI showed a pontine paramedian infarct as the notable cause of PMH. Clinical findings could not definitely distinguish between capsular and pontine PMH, but the combination of dysarthria and a history of previous transient gait abnormality or vertigo favored a pontine location. Outcome at 3 months was characterized by persistent, moderate to severe disability in 86% of patients with pontine PMH versus 46% in capsular PMH. Based on MRI and magnetic resonance angiographic findings, the presumed mechanism of pontine ischemic lesions was a lacunar process in most instances (86%).

Aged↗
PubMed1993

[Arnold-Chiari malformation in adults. Development of diagnostic conditions since the availability of MRI].

We reviewed retrospectively 47 patients with a Chiari malformation (CM) who had been admitted to the Clinique de Neurologie of Lyon from 1971 to 1991. The purpose of this report is to assess the possible influence on the frequency and the clinical pattern at presentation of CM since 1985 when Magnetic Resonance Imaging (MRI) became available to us. A diagnosis of CM was made for 21 patients before 1985 (group 1) and for 26 patients thereafter (group 2), i.e., a 2.5 increase of incidence of CM frequency (1.5 patients/year before 1985 vs 3.7 patients/year thereafter). This increase was even more striking for cases without syringomyelic symptoms and signs (SSS) (42.9% in group 1, vs 76.9% in group 2). The accuracy of clinical diagnosis was 68.1% for the total surveyed period (90.5% before 1985 and 50% thereafter). For cases with SS at presentation, a syringomyelic cavity was radiologically demonstrated in 80% of the cases in the pre-MRI period and 90.9% of the cases since MRI was available. On the other hand, when a syringomyelic cavity was radiologically demonstrated, there was a related clinical SS in 70% of group 1 patients and 50% of group 2 patients.

Adolescent↗
PubMed1993

Spontaneous calcific cerebral emboli from calcified aortic valve stenosis.

Calcific cerebral emboli (CE) are a rare complication of calcified aortic valve stenosis (CAS). These emboli usually result from diagnostic manoeuvres (e.g. left heart catheterization) or from therapeutic procedures (e.g. heart valve surgery). Spontaneous calcific emboli are exceptional. We present the cases of two subjects known to have CAS who presented with acute neurological disorders suggesting strokes. In both subjects CT scans of the skull and brain provided a diagnosis of spontaneous CE by showing calcium-dense dots located on vessels or within the cerebral parenchyma. Additional examinations enabled us to determine the origin (heart or carotid artery) of these emboli. The finding of spontaneous cerebral CE is a very strong argument in favour of surgical valve replacement in these patients.

Adult↗
PubMed1992

Functional neuroimaging strategy in temporal lobe epilepsy: a comparative study of 18FDG-PET and 99mTc-HMPAO-SPECT.

We performed 99mTc-hexamethylpropyleneamineoxime-single-photon emission computed tomography (SPECT) and 18F-fluorodeoxyglucose-positron emission tomography (PET) in 20 epileptic patients with well-lateralized temporal electroencephalographic focus, normal computed tomographic scan, and brain magnetic resonance imaging (MRI) either normal (n = 10) or showing nonspecific changes in the epileptogenic temporal lobe (n = 10). In patients with a normal MRI, PET exhibited focal hypometabolism in 80%, whereas SPECT showed corresponding hypoperfusion in only 20%. In patients with an abnormal MRI, PET and SPECT yielded 100% and 90% sensitivity, respectively. The metabolic and regional cerebral blood flow disturbances were topographically concordant with electroencephalographic and MRI findings in all these patients. Only patients with a large and pronounced hypometabolism on PET images exhibited hypoperfusion on SPECT. Spatial resolution appeared to be the critical factor responsible for the higher sensitivity of PET. However, this superiority of PET did not prove clinically useful in patients whose SPECT was abnormal, particularly when brain MRI showed nonspecific changes in the epileptogenic temporal lobe.

Adolescent↗
PubMed1992

MRI in Sturge-Weber syndrome.

Five children (3 girls, 2 boys, aged from 1 to 18 years) presenting with Sturge-Weber syndrome were explored by MRI with contrast injection in 2 cases. The respective positions of CT and MRI are discussed: CT is the method of choice to display leptomeningeal calcifications. MRI seems to be more accurate than CT to determine the location of the lesions and to demonstrate the enhancement of the angioma after contrast injection.

Adolescent↗
PubMed1992

Haemorrhagic complications of intracerebral cavernomas: value of MRI.

The authors report a retrospective series of 10 cases of intracerebral haematomas consecutive to cavernomas and studied with MRI. The factors that led to the MRI study were the patients' age and clinical history, the site of the haematoma, the persistence of CT images and a negative arteriography. MRI showed that the haematoma was in contact with the cavernoma in 4 cases and at a distance from it in one case. In 5 cases only the cavernoma was seen at the site of the haematoma. Three patients had multiple cavernomas. In all cases, the diagnosis of cavernoma was confirmed at surgical excision.

Adolescent↗
PubMed1991

Magnetic resonance imaging contribution to the diagnosis of spinal cord compression by a subdural arachnoid cyst.

A case of subdural arachnoid cyst of the thoracic spine was studied by magnetic resonance imaging (MRI), myelography and CT myelography. Myelography and especially CT myelography suggested the diagnosis; MRI established it, showing the communication between the cyst and the subarachnoid space. Final characterization was based on surgical findings and pathological examination.

Arachnoid Cysts↗
PubMed1991

Metabolic patterns associated with non-specific magnetic resonance imaging abnormalities in temporal lobe epilepsy.

We investigated the cerebral metabolic patterns associated with non-specific hyperintense T2-weighted image on Magnetic Resonance Imaging (MRI) in Temporal Lobe Epilepsy (TLE). Nineteen patients suffering from TLE with a normal CT scan underwent Positron Emission Tomography (PET) using 18F-fluorodeoxyglucose; 8 had hyperintense T2-weighted image on MRI in the epileptogenic temporal lobe and 11 had a normal MRI. Interictally, PET exhibited focal hypometabolism in all the patients with hyperintense T2-weighted image and in 8 of the 11 whose MRI was normal. The hypometabolic area was significantly more extensive in patients with hyperintense T2-weighted image in whom it always encompasses the site of the MRI abnormality. Moreover, these patients had higher metabolic asymmetry index in the temporal and parietal lobes than patients with a normal MRI. One patient with mesial temporal hyperintense T2-weighted image underwent an ictal PET, which showed that the focal hypermetabolism fitted remarkably with the site and size of the abnormal MR signal. Thus, non-specific hyperintense T2-weighted images are associated with particular interictal and ictal metabolic patterns which might suggest that these MRI abnormalities reflect an epileptogenic lesion.

Adolescent↗
PubMed1990

[Contribution of magnetic resonance imaging in 100 cases of refractory partial epilepsy with normal CT scans].

One hundred epileptic patients were included in this study according to the following criteria: intractable partial epilepsy, normal CT scan and focal EEG abnormalities. Eighty-nine patients were suffering from complex partial seizures of temporal or frontal origin, 55 and 34 cases respectively. Eleven patients presented with only simple partial seizures. MRI was abnormal in 31 patients. The abnormalities were: focal T2 increased signal intensity (13 cases) most often temporal (10 cases), cryptic arteriovenous malformation (4 cases), focal T1 and T2 signal abnormality (4 cases), focal atrophy (2 cases) and multiple abnormal T2 signals scattered in the white matter (8 cases). The site of MRI abnormalities was consistent with electroclinical data in 22 patients, of whom 20 had a temporal lobe epilepsy. Thus MRI proved to be more often abnormal in temporal than in frontal lobe epilepsy (36 p. 100 and 5.9 p. 100 respectively) when the CT scan is normal. However MRI data, particularly focal T2 hypersignals should be confronted to electroclinical and metabolic findings whenever functional surgery is considered.

Adolescent↗
PubMed1990

[Cerebellar imitation synkineses].

Two patients with autosomal dominant pure cortical cerebellar atrophy, belonging to the same family, exhibited imitation synkineses of hands and feet when the contralateral extremity was moved. The phenomenon was observed particularly when alternate movements of one hand were performed, but it also existed when flexion-extension movements of one foot took place. The induced synkinetic movements were mainly observed on the right side in one patient and exclusively observed on the right side in the other one. At electromyography, the imitation synkinesis took place about 200 milliseconds after the first inducing movement, but tended to be simultaneous with the following ones. Imitation synkinesis appeared to be shared by other cerebellar conditions: 8 cases of sporadic pure cerebellar atrophy and 2 cases of post-surgical injury of the anterior lobe vermis. In the 2 genetic cases, there was no pyramidal sign nor sensitive disturbance, the somesthesic evoked potentials being normal. Thus, the imitation synkinesis was considered as having a cerebellar origin. The cerebellar imitation synkinesis might be provoked by the lack of a physiologic cerebellar inhibition located in the paleo- and/or neo-cerebellum. The predominance of imitation synkineses on the right side suggests that cerebellar inhibition is stronger for the dominant side, in order to liberate it from archaic synkineses.

Aged↗
PubMed1990

[Cervicodorsal subdural hematoma caused by coumarinic rodenticide poisoning].

A 59-year old man developed subacute tetraparesis following severe sudden neck pain. MRI showed a subdural cervical hematoma. Prothrombin complex activity was low. An unusual coagulopathy after rodenticides exposure was found. Diphenacoum, an effective antagonist of vitamin K1, was present in the patients plasma. Specific medical management led to a complete recovery. Follow-up MRI seventy days later confirmed the complete disappearance of the hematoma.

4-Hydroxycoumarins↗
PubMed1989

Magnetic resonance imaging in refractory focal epilepsy with normal CT scans.

One hundred patients suffering from focal epilepsy with complex partial seizures refractory to medical treatment and showing no abnormality at CT were explored by MRI with an 0.5 Tesla magnet. MRI detected an abnormality in 25 patients with, in 17 of them, good correlation between MRI and clinical as well as electroencephalographic findings. Abnormal morphology and signal was found in 5 patients, with positive CT results on reexamination of previous CT images or on new CT scans in 4 of them. There was a diffuse temporal lobe high-intensity signal in 3 cases and a localized high-intensity signal in 9 cases (temporal lobe 4, occipital lobe 3, frontal lobe 1, fronto-parietal and parietal lobes 1). Thus, in 13% of the cases MRI demonstrated a lesion that had not been detected at CT, and the location of the lesion was concordant with clinical and electroencephalographic data.

Adolescent↗