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Biomedical subjects

C Raybaud

Publications and source records attributed to C Raybaud.

At least 55 records · Page 3Linked to original sources
PubMed1993

In vivo MRI of the fetal brain.

We report MRI of the brain in 45 fetuses; the findings were confirmed by pathological examination or postnatal neuroradiological studies. MRI necessitates medication to eliminate fetal motion; curare was injected into the umbilical cord, and MRI is therefore limited to cases in which umbilical cord puncture is indicated. T1-weighted images were obtained in axial, sagittal and coronal planes; the last of these were generally as the most useful as regards morphology. We demonstrated cerebral malformations (n = 13), brain haemorrhage (n = 1), a facial angioma (n = 1), a facial mass (n = 1), hydrocephalus (n = 5), unilateral ventricular enlargement (n = 1), atrophy (n = 4), a porencephalic cyst (n = 1) and normal appearances of the brain in 18 cases. Twenty-two of the fetuses were born alive, and the clinical and/or neuroradiological examination confirmed the antenatal findings. The diagnosis was also confirmed in 8 cases in which a neuropathological examination was possible.

Agenesis of Corpus Callosum↗
PubMed1993

Prenatal diagnosis of fetal cerebral abnormalities by ultrasonography and magnetic resonance imaging.

We found magnetic resonance imaging (MRI) of the fetal brain to be effective in confirming or denying diagnosis of fetal cerebral defects when ultrasonography was inconclusive or incomplete. In this paper we describe 31 cases in which ultrasonographic evidence of fetal brain defects was verified by MRI. MRI was performed after curarization of the fetus. In 21 cases, ultrasonographic evidence was confirmed by histological study of the fetus or postnatal radiological examination. In 10 cases, ultrasonographic diagnosis was denied by MRI and healthy infants were born. In one case of cerebral toxoplasmosis, ultrasonography detected periventricular calcifications but MRI was normal. In 20 cases MRI ascertained or further documented the ultrasonographic findings. However in 4 of these 20 cases autopsy of the fetus was required to determine the exact nature of the lesion.

Adult↗
PubMed1993

Evaluation of three-dimensional MRI exploration of prolactin-secreting microadenomas.

Over an 8-month period (July 1990-to February 1991), we explored 21 women presenting with a clinical and laboratory profile of prolactin-secreting microadenoma of the pituitary gland. Magnetic resonance imaging (MRI) is undoubtedly the most efficient method to explore microadenomas, especially when carried out in the absence of any treatment. In 8 cases, MRI was performed in the absence of medical treatment and gave a positive result, i.e. always showed a focal lesion. In the remaining 13 cases the patients had been treated before the exploration, and MRI detected a microadenoma in only 4 cases. The duration of treatment and the time elapsed between its withdrawal and the MRI examination did not seem to influence the positivity or negativity of the imaging results. Among the 9 cases where MRI failed to show a focal lesion, the image was normal in 3 cases and displayed an arachnoidocele in 3 cases; the pituitary gland was convex and homogeneous in 1 case and convex and heterogenous in 3 cases, which raised the problem of the effects of bromocriptine on the MRI images. As regards signals, in 5 cases the microadenoma was hyperintense on the spin-echo sequence without contrast injection; it was undetectable on the same sequence in 2 cases. In 4 cases the lesion was contrast-enhanced after gadolinium injection. Using millimetric sections enables small-size adenomas (2.5 x 3 mm) to be visualized.

Adolescent↗
PubMed1993

MRI exploration of the intrapetrous facial nerve.

We report our experience of intrapetrous facial nerve evaluation in 33 patients examined by three-dimensional MRI (3D-FT) with intravenous gadolinium injection. The examinations were performed by a 1 Tesla magnet, using Flash and Turbo-Flash sequences which enabled us to obtain contiguous millimetric sections and to make reconstructions in all planes. Among these 33 patients, 31 had facial palsy and 2 a facial nerve lesion without clinical signs and discovered by chance. Facial palsy had started rather abruptly in 26 cases. It was either idiopathic (n = 20) or caused by herpes zoster (n = 1), injuries (n = 2), metastasis (n = 1) and tumour (n = 1); it was concomitant with a granuloma in 1 case. Five patients seen or explored late had congenital cholesteatoma (n = 2), facial nerve neurinoma (n = 2) or persistent idiopathic facial palsy (n = 1). There was no contrast enhancement in "chronic" non tumoral facial palsy. All tumours (neurinoma, neurofibroma, metastasis) were contrast-enhanced, as were the 2 cases of traumatic palsy and the case with granuloma of the labyrinth. In acute idiopathic facial palsy (n = 20), contrast enhancement was demonstrated in 11 patients; among these, recovery was complete at 2 months in 1 case and incomplete in 9 cases; 1 patient was lost sight of. In the 9 patients without contrast enhancement, recovery was complete in 7; 2 patients were lost sight of. This study shows that minute lesions of the facial nerve can be detected with millimetric MRI T1-weighted sequences and contrast enhancement. It also suggests that contrast enhancement has some prognostic value in patients with acute idiopathic facial palsy.

Acute Disease↗
PubMed1992

M4 protocol for cerebellar medulloblastoma: supratentorial radiotherapy may not be avoided.

The main goal of the M4 protocol was to evaluate the efficacy of treatment excluding supratentorial radiation in patients with newly diagnosed medulloblastoma. All patients underwent surgical resection and received postoperative chemotherapy. Chemotherapy was adapted to the initial staging and prognostic factors (Group A: good-risk; Group B: poor-risk). Chemotherapy was started early after surgery, and consisted of two courses of the "eight drug in one day" regimen and two courses of high dose methotrexate. Radiotherapy was delayed until 5 (Group B) to 7 (Group A) weeks after the first course of chemotherapy. Radiotherapy was administered only to the posterior fossa and the spinal axis. Only 3/16 patients (18%) are alive and disease-free with a mean follow up of 6 years. The site of progression was supratentorial in 9 out of 13 patients and three patients had spinal and/or cerebrospinal fluid relapses. Only one patient had isolated posterior fossa relapse. The mean time to relapse was 484 days. We conclude that the chemotherapy regimens used in the M4 protocol do not allow the reduction of irradiation fields in patients with cerebellar medulloblastoma. In spite of long-term side effects on neurocognitive functions, supratentorial radiotherapy should remain a major component of medulloblastoma treatment.

Adolescent↗
PubMed1992

Neurological findings and seizure outcome in children with bilateral opercular macrogyric-like changes detected by MRI.

The authors studied 10 patients aged between six and 23 years (mean age 14 years 5 months) with magnetic resonance imaging, which detected bilateral 'macrogyric-like' maldevelopment of the insulo-opercular regions. The data confirm that biopercular gyral anomaly, associated with mental retardation, pseudobulbar palsy (cortical or central) and epilepsy, represents an anatomo-clinical syndrome. Nevertheless, a wide clinical spectrum was found varying from pictures correlating with the topography and extent of the MRI-detected anomaly to conditions indicating wider cerebral involvement. Epilepsy, varying greatly in age at onset and severity, consistently influenced the prognosis for five patients with diffuse EEG abnormalities and intractable seizures with falls. Anterior callosotomy relieved such seizures in one case.

Adolescent↗
PubMed1992

Epilepsy and focal gyral anomalies detected by MRI: electroclinico-morphological correlations and follow-up.

The authors studied 10 patients (mean age 15 years 6 months) with localized developmental gyral disorder detected by MRI. There were two groups of major malformations. Seven patients (group 1) had unilateral 'macrogyric-like' insulo-opercular changes, one of whom died early in life and had extensive microgyria. The six others had mental retardation and epilepsy, three of whom had focal neurological signs. Age at onset of epilepsy varied greatly. Clinical and EEG data suggested a wider cerebral involvement than recognized on MRI. The remaining three patients (group 2) had abnormal gyri of variable topography and extension, with bulging grey matter and ventricular deformity. One had mental retardation, another had neurological signs. All had intractable complex partial seizures and focal EEG anomalies correlating with the MRI lesion site, pointing to a well-defined epileptogenic zone. No clinical or EEG evidence of significant malformation in the remaining brain tissue was observed. Ablative surgery was beneficial for one patient; focal cortical dysplasia was the pathological substrate.

Adolescent↗
PubMed1992

[MRI of the spinal epidural fat in pathology].

The authors report about their experience with the merits of the normal systematization of epidural fat with MRI. On sagittal sections, this fat has a variable appearance, but its location along the spinal canal is constant. On axial sections, its morphology is suggestive of the level of section: cervical, upper or lower thoracic, lumbar. Some changes in this fat are precious data to explain local hypertrophy (scoliosis) or to locate an intra- or extradural process.

Adipose Tissue↗
PubMed1992

[Ewing's tumor: current knowledge and ignorance].

The diagnosis of Ewing's malignant tumor in the young still raises major problems, either from a clinical point of view because of its rarity, its pluri-potentiality and various symptoms, or on imaging because of its numerous pitfalls. Accordingly the disease is often misdiagnosed as osteomyelitis. Only a high quality biopsy can determine histological diagnosis of undifferentiated small round cell tumor. The chromosomic study shows a specific (11;22)(q24;q12) translocation, and immunocytochemistry and molecular biology show the tumor's neuroectodermal origin. For 20 years, therapy tended toward first line tumor chemoreduction, followed, when appropriate, by complete resection and orthopedic reconstruction of the bone. Radiotherapy, which is responsible for long-term sequelae is now increasingly restricted to inaccessible or incompletely excised tumors. More intensive chemotherapy is being examined in patients with poor prognosis factors such as a negative response to induction chemotherapy, a significant mass or metastases. As a result of new strategies, disease-free survival rate is now between 60-70%. The management of this disease is highly multidisciplinary and patients will now be included in multicentric controlled therapeutic trials. Long term follow-up has to be carried out following completion of treatment.

Adolescent↗
PubMed1992

[Drash syndrome].

The authors report one case of Drash syndrome: association of Wilms' tumor, nephropathy and genital abnormalities. The definition, prognosis and origin of this triad are discussed.

Cadaver↗
PubMed1992

[Evaluation of nuclear magnetic resonance imaging in tridimensional acquisition in the investigation of prolactin microadenoma].

Twenty one patients with suspected prolactin-secreting microadenoma were evaluated with MRI. MRI is the most sensitive means for detecting focal microadenomas. In these patients who were clinically and endocrinologically considered to harbor a microadenoma, MR detected a focal pituitary signal abnormality in 100% when the patients had not previously taken bromocriptine therapy. On the other hand MR demonstrated a focal abnormality in only 30% of cases when the patients had been on dopamine agonist therapy: the MRI findings in the group of bromocriptine treated patients are not affected by neither the duration and dosage of the therapy or the delay between MR examination and the bromocriptine therapy discontinuation. Among the 9 cases in which MRI did not demonstrate a focal abnormality, MRI was strictly normal in 3 cases only; MR showed a localized expansion of the subarachnoid space in two cases; the pituitary gland was large and round, and had a homogeneous signal in one case; the pituitary gland had a heterogeneous signal in 3 cases. In our study the microadenoma had a high signal intensity on the precontrast T1 weighted sequence in 5 cases. The focal abnormality was not seen on the precontrast MR images in 2 cases. The microadenoma enhanced in 3 cases on the postcontrast three dimensional MR images. This MR technique allows thin section slices (1 mm) and therefore the detection of small focal abnormality of the pituitary gland (2.5 x 3 mm). Thus three points have to the emphasized: a) MRI always detected a microadenoma when the patients had never received a bromocriptine therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Ataxic hemiparesis and simultaneous supra- and subtentorial hematomas].

In a chronically hypertensive woman with a rapidly developing right ataxic hemiparesis syndrome, computed tomography and magnetic resonance imaging (MRI) revealed two small unrelated hemorrhages: one in the posterior limb of the left internal capsule, the other in the right cerebellar hemisphere. In this patient, the ataxic hemiparesis syndrome might have resulted either from the association of the two lesions or from the capsular hemorrhage alone. The rarity of simultaneous hypertensive hematomas and the value of MRI in the diagnosis are underlined.

Aged↗
PubMed1991

MRI study of brain myelination.

Brain development in infants is characterized by growth and myelination. Myelin is a cell membrane devoid of MRI signal; the MRI images obtained at different stages of myelination result from changes in brain tissue water content, from the multiplication of glial cells which precedes myelination (the so-called myelination gliosis), and from the accumulation of lipid myelin precursors contained in cells. T1-weighted sequences are used for the "premyelination" process and T2-weighted sequences for myelination proper. The development of myelination in the white matter is sequential, precisely determined, identical in all individuals, and it has been well studied by histologists. In vivo, myelination in infants is shown at MRI as the same precise sequence but with some changes in time towards the end. The myelination process takes place at different times and different speeds in different brain regions, and for any given structure the speed of myelination varies in relation to time.

Age Factors↗