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G Sebag

Publications and source records attributed to G Sebag.

At least 37 records · Page 2Linked to original sources
PubMed1997

Supratentorial parenchyma in the developing fetal brain: in vitro MR study with histologic comparison.

PURPOSE: To assess the in vitro MR signal of the developing brain through histologic comparisons. METHODS: Five healthy fetal specimens aged 16, 19, 22, 27, and 34 gestational weeks were studied in vitro using T1- and T2-weighted sequences in frontal and axial planes. Neuropathologic studies included sections in the same frontal plane. Comparison of histologic sections with measurements of the relative widths of the layers of different signal intensities enabled us to assign cellular correspondence to each MR layer. RESULTS: In the cerebral mantle, a layered pattern was observed on both T1- and T2-weighted images. In the basal ganglia, signal from the pallidum and thalamus was isointense with white matter from 16 to 22 weeks' gestation; then, from 27 and 34 weeks' gestation, the signal was relatively high on T1-weighted images and low on T2-weighted images. The neostriatum had a relatively low signal on T1-weighted images and a high signal on T2-weighted images from 16 to 27 weeks' gestation: then, at 34 weeks' gestation, the signal was relatively high on T1-weighted images and low on T2-weighted images. CONCLUSION: MR imaging can clearly show specific patterns of growing fetal brain in vitro.

Basal Ganglia↗
PubMed1996

[Magnetic resonance imaging of the fetus. Contribution to antenatal diagnosis].

Magnetic resonance imaging (MRI) of the fetus has been developed over the last 10 to 15 years. This new imaging technique cannot remplace ultrasonography which remains the key examination for antenatal diagnosis but can add further improvements over ultrasonographic findings, particularly in evaluating the fetal brain. MRI of the fetus has thus been focused in this area, the main studies aiming at analyzing brain malformations and at searching for ischemic or hemorrhagic lesions and possible gyration anomalies. Advances in data processing software and volume acquisition and the development of the echo-planar technique and T2-weighted sequences are currently under study. MRI of the fetus has thus progressed rapidly. It is however a long costly examination which may not be well tolerated by pregnant women. Currently, routine MRI of the fetus is not possible, because of the requirement for specialized facilities. This new technique, still in the evaluation phase, should be studied using strict protocols reserved for centers specialized in antenatal diagnosis.

Female↗
PubMed1996

[Mental prognosis of Apert syndrome].

BACKGROUND: Mental retardation, considered as common in Apert syndrome could be in part due to associated brain abnormalities. POPULATION AND METHODS: Sixty patients (32 males, 28 females) were included in the study. Patient age at the last examination was over 3 years (mean 10 years, range 3-28 years) in 38 patients. IQ was assessed from psychometric tests adapted for age. Brain anatomy was studied by MRI. Age at operation and quality of familial environment were also evaluated. RESULTS: The IQ was over 70 in 12 patients (32%), over 90 in five (13%) and the mean IQ was 62 (10-114). Thirty percent of patients had abnormalities of the corpus callosum, 43% of the cerebral ventricles and 55% of the septum pellucidum. There was no anomaly in 28% of the patients. One or more operations were performed in 53 patients, before one year of age in 37. Ten children were institutionalized or in deleterious family situation. The main factor influencing the mental prognosis was the age at operation: the final IQ was over 70 in 50% of the children operated on before one year of age versus 8% in those operated on later (P = 0.01). Only the anomalies of the septum pellucidum seemed to play a role: 50% of the patients with normal septum had an IQ > 70 compared to 18% in those with septum anomalies (P < 0.04). The quality of the familial environment also influenced the mental development: 12.5% of the patients who were institutionalized or in difficult familial situation had an IQ > 70 compared to 39% of those who live in a normal family. CONCLUSIONS: Careful investigation including MRI is necessary for detecting associated brain abnormalities. The patients must be operated on early, if possible before the age of nine months. Attention has also to be paid to quality of the sociofamilial environment.

Acrocephalosyndactylia↗
PubMed1996

[Chiari "malformation" in Crouzon syndrome].

BACKGROUND: Use of MRI makes the association Chiari malformation-cranio-facial synostosis more frequent than expected. The aim of this work was to ascertain the true incidence of Chiari malformation and to understand the reasons of the association between a bone pathology and a CNS malformation. PATIENTS AND METHODS: The anatomy of the posterior cranial fossa in Crouzon syndrome was retrospectively studied on MRI scan in 49 patients. RESULTS: A chronic tonsillar herniation, similar to a Chiari malformation, was observed in 71.4% of the cases. All the patients with Crouzon syndrome and progressive hydrocephalus had a Chiari malformation, but only 19 out of the 33 patients without associated hydrocephalus had a Chiari malformation (57.6%). Significant differences between the pattern of lambdoid suture closure were founded between both groups, with and without Chiari malformation, the lambdoid closure appearing earlier in patients with Chiari malformation. CONCLUSION: The high incidence of chronic tonsillar herniation in Crouzon syndrome seems related to the premature synostosis of the lambdoid suture.

Actuarial Analysis↗
PubMed1996

Prognosis for mental function in Apert's syndrome.

The factors involved in the mental development of patients with Apert's syndrome were studied by the authors, focusing on the age of the patient at operation, associated brain malformations, and the quality of the family environment. Overall, 32% of patients with significant follow-up review had an intelligence quotient (IQ) greater than 70. Age at operation appeared to be the main factor associated with changes in mental development: final IQ was greater than 70 in 50% of patients operated on before 1 year of age versus only 7.1% in patients operated on later in life (p = 0.01). Malformations of the corpus callosum and size of the ventricles played no role in the final IQ, whereas anomalies of the septum pellucidum had a significant effect, with the proportion of patients with an IQ over 70 increasing more than twofold in patients with a normal septum compared with patients with septal anomalies (p < 0.04). Quality of the family environment was the third factor involved in intellectual achievement: only 12.5% of institutionalized children reached a normal IQ level compared to 39.3% of children from a normal family background.

Acrocephalosyndactylia↗
PubMed1995

Hyperinsulinism in children: diagnostic value of pancreatic venous sampling correlated with clinical, pathological and surgical outcome in 25 cases.

Neonatal hypoglycemia represents an emergency of heterogeneous etiology. The occurrence of persistent hypoglycemia caused by hyperinsulinism has not been well established. Some authors claim that it may be more common than previously suggested. The diagnostic goal is to distinguish hyperinsulinemia from other causes of hypoglycemia because management strategies differ. The diagnosis of persistent hypoglycemia attributable to hyperinsulinism is made when insulin secretion is excessive or inappropriate (> 10 microIU/ml). Medical management includes frequent feeding, high hydrocarbon intake, glucagon, diazoxide, somatostatin or steroid treatment. In case of resistance to medical intervention, surgery consisting of subtotal pancreatectomy is performed to avoid neurological sequelae. However, pediatric organic hypoglycemia secondary to hyperinsulinism can be caused by either diffuse or focal pancreatic lesions. Differentiation between these two types of lesion is necessary since partial pancreatectomy can prevent diabetes. In this prospective study, pancreatic venous sampling (PVS) was evaluated for the preoperative localization of lesions in 25 children with hyperinsulinism and correlated with surgical, pathological and clinical outcome. PVS is the most accurate preoperative technique for localizing focal lesions in children. Besides being safe and effective, it has the great advantage of detecting focal secretion, thus reducing the need for extensive surgery.

Adolescent↗
PubMed1995

Hydrocephalus associated with intramedullary low-grade glioma. Illustrative cases and review of the literature.

Over the past 15 years, eight children affected by intramedullary low-grade gliomas associated with hydrocephalus were treated at l'Hôpital des Enfants Malades. In all cases the diagnosis of hydrocephalus was made prior to that of the spinal tumor. Neuroradiological examination of all patients revealed contrast enhancement of the intracranial subarachnoid spaces. In six cases this was progressive, suggesting subarachnoid spread of the tumor, which was confirmed in two cases by histological examination. The authors analyzed 38 cases of intramedullary low-grade glioma associated with hydrocephalus that were reported in the literature. Fifteen of the cases had intracranial leptomeningeal seeding. Several hypotheses have been proposed to explain this unusual association, such as 1) increase in cerebrospinal fluid (CSF) viscosity because of elevated fluid protein content; 2) obliteration of the cisterna magna due to a rostral extension of the tumor; and 3) blockage of the spinal subarachnoid pathways of CSF resorption. Two other theories seem of particular interest. Bamford and Labadie suggested that the abnormal presence of fibrinogen in the CSF and its transformation into fibrin at the level of the basal cisterns and Pacchioni's granulation may alter CSF hydrodynamics. This mechanism alone is sufficient to induce hydrocephalus of the communicating type. In addition, as suggested by Maurice-Williams and Lucey, the resulting leptomeningeal fibrosis might predispose secondary implantation of neoplastic elements in the subarachnoid spaces of the intracranial compartment.

Adolescent↗
PubMed1995

Chronic tonsillar herniation in Crouzon's and Apert's syndromes: the role of premature synostosis of the lambdoid suture.

The incidence of chronic tonsillar herniation (CTH) was evaluated with magnetic resonance imaging in 44 patients with Crouzon's syndrome and 51 with Apert's syndrome; the incidence was 72.7% in Crouzon's syndrome and 1.9% in Apert's syndrome. All the patients with Crouzon's syndrome and progressive hydrocephalus had CTH, but of 32 individuals with Crouzon's syndrome and CTH, only 15 had progressive hydrocephalus. Five patients with Apert's syndrome were treated for progressive hydrocephalus; none had CTH. The patterns of suture closure in these two groups of patients were studied, and significant differences in coronal, sagittal, and lambdoid sutures were found between patients with Crouzon's and Apert's syndromes. In Crouzon's syndrome, significant differences in the pattern of lambdoid suture closure were found between the groups with and without CTH; in the group with CTH, the lambdoid closure appeared earlier. The authors propose that the high incidence of individuals with CTH who have Crouzon's syndrome is related to the premature synostosis of the lambdoid suture in the first 24 months of age.

Acrocephalosyndactylia↗
PubMed1995

[Preoperative X-ray computed tomographic evaluation of major aplasia of the ear in children].

PURPOSE: To describe computed tomography (CT) findings in congenital aural atresia (CAA) and to illustrate the impact of these findings in the preoperative evaluation. MATERIALS AND METHODS: Sixty-seven congenital aural atresia (bilateral: 10) in 57 children were studied using high resolution CT. Sections 1.5 mm thick were removed from the coronal and the axial plans without sedation (mean age: 9, 6 years). RESULTS AND DISCUSSION: A narrow bony external auditory canal (EAC) was present in 24% of the cases. In one of these cases, the EAC contained a cholesteatoma and was consequently a clear indication of surgery. An hyperpneumatized mastoïd (22%), a posterior position of the temporo mandibular joint (16%), and a bulging medial temporal fossa (12%) made the operation much more difficult. The tympanic cavity was small in 68% of the cases, normal in 28% and absent in 4% of the cases without any detectable ossicular chain. Ossicular chain anomalies were present in 91% of the cases. This consisted most frequently of a fusion of the malleus and the incus (76%) with or without fusion to the tympanic wall (33%). Lateral and anterior displacement of the descending portion of the facial nerve was present in 62%. Oval and round windows were normal in 86% of the cases. A soft tissue opacity (33%) in the tympanic cavity made it difficult to evaluate the stapes, the incudo stapedial articulation, and the facial nerve. Simultaneous abnormalities of inner ear were exceptional (1 case). CONCLUSION: High resolution CT is the best method in CAA evaluation and for guiding the planning of the surgical correction.

Child↗
PubMed1994

[Imaging of joints in children].

Magnetic resonance imaging (MRI) has became the technique of choice for noninvasive imaging of the joint in the child, owing to its high tissular contrast. Through injection of paramagnetic contrast media, MRI allows a precise analysis of the synovial inflammation, of the cartilage and of the joint effusion. It offers a precise evaluation of the local activity of the disease. It guides and provides monitoring of local treatment in juvenile chronic arthritis and haemophilic arthropathy. The technique is very sensitive but lacks specificity. Its use is complementary to clinical examination and standard radiography techniques, which remain the initial investigations.

Adolescent↗
PubMed1994

Stroke and cerebral infarcts in children infected with human immunodeficiency virus.

OBJECTIVE: To study the causes of stroke and cerebral infarcts in children infected with the human immunodeficiency virus (HIV)-type 1. DESIGN: Case series. PATIENTS: Four of 380 HIV-infected children followed up in a 10-year period in our department who had a stroke with evidence of cerebral infarcts on radiological imaging. RESULTS: The four patients were severely immunodepressed, but their clinical status and outcome were different. Aneurysmal dilation of major cerebral arteries and thrombosis of these arteries or of small cortical vessels were discovered in two patients. Both patients had a history of frequent infections and had suffered repeated neurological events that resulted in severe clinical deterioration or death. An infectious causative agent was strongly suspected but was not detected. The other two patients had a more favorable outcome. An isolated cerebrovascular thrombosis was found in one patient, while in the other, HIV-1-related focal necrosis was suggested by the lack of permanent cerebrovascular abnormalities or thrombosis and by signs of necrosis in biopsy specimens of the brain. CONCLUSION: Stroke and cerebral infarcts in HIV-1 infected children have different causes and different prognoses.

Adolescent↗
PubMed1994

Gadolinium-DOTA enhanced MRI of painful osseous crises in children with sickle cell anemia.

In order to evaluate the role of gadolinium-DOTA enhanced MRI in the management of painful osseous crises in children with sickle cell anemia (SCA), nine children with SCA underwent MRI, bone scans and ultrasonographic studies during 11 osseous crises. Imaging findings were compared with the final diagnosis: three acute osteomyelitis (AO) and 16 acute infarcts (AI). MRI could not differentiate AO from AI. The appearance of severe AI was very misleading and was similar to the usual appearance of AO, including soft tissue changes, periosteal reaction and patterns of enhancement. Gadolinium-DOTA enhanced MRI was useful for determining the anatomic site and extent of AO or AI and for distinguishing between necrotic material, fluid collection and vascularized inflammatory tissue. It can also help to guide the aspiration of intraosseous, subperiosteal and soft tissue fluid collections.

Acute Disease↗
PubMed1993

Serious childhood angiomas: unsuccessful alpha-2b interferon treatment. A report of four cases.

Over a 4-year period, we managed four children with alarming haemangiomas (two cases of Kasabach-Merritt syndrome and two life-threatening haemangiomas). Systemic steroid therapy was ineffective. Other treatments (radiotherapy, anti-platelet drugs) were also ineffective in the Kasabach-Merritt patients. On the basis of recent reports on the effects of interferon on endothelial cells, we used alpha-2 interferon therapy, but obtained no response.

Arm↗
PubMed1992

[Kasabach-Merritt syndrome in children].

Kasabach-Merritt syndrome is a combination of thrombocytopenia, intravascular coagulation, and a rapid increase in the size of an angioma. Anemia and disseminated intravascular coagulation may develop. This infrequent syndrome is severe and may be life-threatening. Pathophysiologic mechanisms underlying the condition are incompletely understood and, consequently, many different treatments are used, including systemic corticosteroids, compression, embolization, antifibrinolytic agents, platelet aggregation inhibitors, irradiation, and others. From findings in eight personal cases, the authors review clinical and biological features, pathophysiologic hypotheses and therapeutic strategies.

Aspirin↗
PubMed1991

[Epidural chordoma without bone involvement. A propos of a case in a child. Review of the literature].

The authors report the case of a chordoma developed exclusively in the epidural space at the L1-L2 level in a 6 year old child. The tumor was easily removed in toto. No post-operative radiotherapy was given. The diagnosis of chordoma was based on the histological characteristics of the lesion and the results of immunohistological studies which were both typical of this lesion. This observation is exceptional because of the young age of the patient, the lumbar level of the tumor and, even more, the absence of any bone involvement. The 8 previously published cases of chordoma developed along the craniospinal axis but without bone involvement are reviewed and analysed: all were subdural; 7 were intracranial (6 prepontic, 1 suprasellar): only one was intraspinal. These lesions raise the problem of their diagnosis, of their treatment and of their embryogenesis. They could develop from ectopic notochordal remnants: the "ecchondrosis physaliphura".

Child↗