G Sebag

Hôpital Universitaire Robert Debré, Lutetia Parisorum, Île-de-France, France

Are you G Sebag?

Claim your profile

Publications (135)180.5 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Cerebral vasculopathy is a serious complication of sickle cell anemia. Overt strokes are largely due to intracranial arteriopathy, detected by routine transcranial Doppler and largely prevented through chronic transfusions. As extracranial internal carotid artery arteriopathy was considered rare, it has not been routinely assessed in sickle cell anemia. Recent cases of overt strokes associated with stenosis/occlusion of the extracranial portion of the internal carotid artery prompted us to include extracranial internal carotid artery assessment to our transcranial Doppler sonography protocol. The aim of the study was to perform a cross-sectional study in children with sickle cell anemia to evaluate Doppler flow patterns of the extracranial internal carotid arteries and to assess potential associated factors. Between June 2011 and April 2012, 435 consecutive stroke-free children with sickle cell anemia (200/235 M/F, median age: 7.9 years) were assessed for extracranial internal carotid artery using a 2-MHz transcranial Doppler sonography probe via a submandibular window during routine transcranial Doppler sonography visits. The course of both extracranial internal carotid artery was assessed by color Doppler mapping, and the highest flow velocity was recorded after insonation of the entire length of the artery and analyzed. Intra- and extracranial MR angiographies were available in 104/435 subjects for comparison. Mean (SD) extracranial internal carotid artery time-averaged mean of maximum velocity was 96 (40) cm/s. Extracranial internal carotid artery tortuosities were echo-detected in 25% cases and were more frequent in boys (33% vs.18%; P < 0.001). Velocity ≥160 cm/s in at least one extracranial internal carotid artery was found in 45 out of 435 patients with sickle cell anemia (10.3%) and was highly predictive of MR angiography stenosis. Simultaneous abnormal intracranial velocity (≥200 cm/s) was recorded in 5/45 patients, while 40 patients had isolated extracranial internal carotid artery velocity ≥160 cm/s. Low hemoglobin (odds ratio: 1.9/g/dL, 95% confidence interval (CI): 1.3-2.9; P = 0.001) and tortuosities (odds ratio: 19.2, 95% CI: 7.1-52.6; P < 0.001) were significant and independent associated factors for isolated extracranial internal carotid artery velocities ≥160 cm/s. Adding extracranial internal carotid artery evaluation via the submandibular window to transcranial Doppler sonograpy allowed us to detect 10.3% patients at risk for extracranial internal carotid arteriopathy. Further studies are needed to evaluate the prognosis of these anomalies.
    Pediatric Radiology 03/2014; · 1.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To determine the reproducibility, the inter-hemispheric difference and the reference ADC values of the fetal brain according to gestational age. 101 normal fetal brain (29.4 to 38.4 weeks) were analysed with DWI. ADC was measured in frontal (FWM), occipital white matter (OWM), Centrum Semi Ovale (CSO), basal ganglia (BG), cerebellar hemisphere (CBM) and pons. ADC ratio (fronto-occipital, fronto-cerebellar and occipito-cerebellar) were calculated. Inter-observer reproducibility was assessed on 27 studies, using intra-class correlation coefficient (ICC) and Bland-Altman plot. Inter-hemispheric difference was evaluated with Bland-Altman plot. Gestation-specific reference intervals were estimated for each brain region. Inter-observer bias was near zero. Limits of agreement (LOA) were clinically acceptable (-0.17; 0.20 to -0.38; 0.31 x10-3 mm2/s) for all brain regions except for CSO and pons.Inter-hemispheric bias was near zero. Smallest LOA were for FWM (± 0.09 mm2/s) and BG (± 0.019 mm2/s). ADC values decreased, whereas ADC ratio increased with gestational age, reflecting normal maturation. Fronto-occipital, fronto-cerebellar and occipito-cerebellar ratios were consistently above 0.8, 1 and 1 respectively. The fetal brain regions with the highest reproducibility and smallest interhemispheric differences are the frontal, occipital, cerebellar white matter and basal ganglia. ADC ratio could be useful to assess differential temporo-spatial maturation. This article is protected by copyright. All rights reserved.
    Prenatal Diagnosis 12/2013; · 2.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ultrasound prenatal evaluation of pelvic cystic mass can be challenging. After having ruled out a cloaca anterior to a large hydrocolpos, it is important to differentiate between combined urogenital anomalies such as urogenital sinus and isolated genital anomalies. We reviewed the charts of 13 women referred for a third trimester pelvic MRI for cystic pelvic mass discovered in second trimester ultrasound. We evaluated MRI compared with postnatal surgical findings in order to determine clues for improving prenatal diagnoses. MRI excluded the diagnosis of cloacal malformation in nine cases with no false negative. Once a cloaca is ruled out, a different signal between the bladder and the hydrocolpos on T2 sequences is in favor of an isolated genital obstruction. In contrast, in case of urogenital sinus, the vagina is filled with a mixture of genital secretions and urine, which gives it an MRI signal similar to the bladder on T2 sequences. Third trimester fetal MRI is an essential exam for characterization of pelvic cystic mass diagnosed by ultrasound. This exam appears valuable for invalidating the diagnosis of cloacal malformation and for differentiating between isolated genital obstruction and urogenital sinus.
    Journal of pediatric urology 09/2013; · 1.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: Computed tomography can be used for three-dimensional (3D) evaluation of adolescent idiopathic scoliosis (AIS) patients, but at the expense of high radiation exposure, and with the limitation of being performed in the supine position. These drawbacks can now be avoided with low-dose stereoradiography, even in routine clinical use. The purpose of this study was to determine the 3D postoperative correction of AIS patients treated by posteromedial translation. METHODS: Forty-nine consecutive patients operated for AIS (Lenke 1-4) using posteromedial translation were included. Corrections were evaluated preoperatively, postoperatively and after at least 2 years using the EOS imaging system. 3D angles were measured in the plane of maximum deformity. RESULTS: Mean number of levels fused and operative time were 13.5 ± 1 and 215 ± 25 min, respectively. Main thoracic, proximal thoracic, and lumbar curves corrections averaged 64.4 ± 18, 31 ± 10 and 69 ± 20 %, respectively. Mean T4-T12 kyphosis increased 18.8° ± 9° in the subgroup of hypokyphotic patients. Mean apical vertebral rotation reduction was 48.3 ± 20 %. Trunk height gain averaged 27.8 ± 14 mm. There was no pseudarthrosis or significant loss of correction in any plane during follow-up. Two patients (4 %) developed asymptomatic proximal junctional kyphosis, despite having normal thoracic kyphosis. Their sagittal balance was shifted posteriorly by 36 and 47 mm, respectively, by the operation, but revision surgery was not performed. CONCLUSIONS: Low-dose stereoradiography provided 3D reconstructions of the fused and unfused spine in routine clinical use. Postoperative 3D analysis showed that posteromedial translation enhanced sagittal balance correction, without sacrificing frontal or axial correction of the deformity.
    European Spine Journal 04/2013; · 2.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: STUDY DESIGN: Radiological reproducibility study. PURPOSE: To assess intra and interobserver reliability of radiographic measurements for global sagittal balance parameters and sagittal spine curves, including cervical spine. Sagittal spine balance in adolescent idiopathic scoliosis (AIS) is a main issue and many studies have been reported, showing that coronal and sagittal deformities often involve sagittal cervical unbalance. Global sagittal balance aims to obtain a horizontal gaze and gravity line at top of hips when subject is in a static position, involving adjustment of each spine curvature in the sagittal plane. To our knowledge, no study did use a methodologically validated imaging analysis tool able to appreciate sagittal spine contours and distances in AIS and especially in the cervical region. METHODS: Lateral full-spine low-dose EOS radiographs were performed in 75 patients divided in three groups (control subjects, AIS, operated AIS). Three observers digitally analyzed twice each radiograph and 11 sagittal measures were collected for each image. Reliability was assessed calculating intraobserver Pearson's r correlation coefficient, interobserver intra-class correlation coefficient (ICC) completed with a two-by-two Bland-Altman plot analysis. RESULTS: This measurement method has shown excellent intra and interobserver reliability in all parameters, sagittal curvatures, pelvic parameters and global sagittal balance. CONCLUSIONS: This study validated a simple and efficient tool in AIS sagittal contour analysis. It defined new relevant landmarks allowing to characterize cervical segmental curvatures and cervical involvement in global balance.
    European Spine Journal 03/2013; · 2.47 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: This study aims to evaluate the use of fetal brain magnetic resonance imaging (MRI) following an antenatal sonographic diagnosis of isolated cleft lip with or without cleft palate (CL/P). METHOD: This was a retrospective study of 92 fetuses antenatally diagnosed with isolated CL/P on screening ultrasound. All patients underwent expert diagnostic antenatal ultrasound, fetal brain MRI, and karyotype analysis. RESULTS: Five cases were excluded from the study as associated abnormalities were detected on expert ultrasound: corpus callosum agenesis (n = 1), retrognathism (n = 3), and ectrodactyly (n = 1). Fetal MRI diagnosed unsuspected midline cerebral abnormalities in four out of the 87 remaining cases (4.6%): vermis agenesis (n = 1), isolated arhinencephaly (n = 2), and suspicion of pituitary abnormality (n = 1). All karyotype analyses were normal. CONCLUSION: In CL/P, the incidence of associated cerebral abnormalities overlooked on ultrasound is 4.6%. Careful evaluation of midline structures by expert ultrasound in CL/P is necessary and may be sufficient. MRI can be useful if the US examination is limited or in case of family history. However, the choice to proceed to fetal MRI may vary from institution to institution. © 2013 John Wiley & Sons, Ltd.
    Prenatal Diagnosis 01/2013; · 2.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND AND PURPOSE:Waardenburg syndrome, characterized by deafness and pigmentation abnormalities, is clinically and genetically heterogeneous, consisting of 4 distinct subtypes and involving several genes. SOX10 mutations have been found both in types 2 and 4 Waardenburg syndrome and neurologic variants. The purpose of this study was to evaluate both the full spectrum and relative frequencies of inner ear malformations in these patients.MATERIALS AND METHODS:Fifteen patients with Waardenburg syndrome and different SOX10 mutations were studied retrospectively. Imaging was performed between February 2000 and March 2010 for cochlear implant work-up, diagnosis of hearing loss, and/or evaluation of neurologic impairment. Eleven patients had both CT and MR imaging examinations, 3 had MR imaging only, and 1 had CT only.RESULTS:Temporal bone abnormalities were bilateral. The most frequent pattern associated agenesis or hypoplasia of ≥1 semicircular canal, an enlarged vestibule, and a cochlea with a reduced size and occasionally an abnormal shape, but with normal partition in the 13/15 cases that could be analyzed. Three patients lacked a cochlear nerve, bilaterally in 2 patients. In addition, associated abnormalities were found when adequate MR imaging sequences were available: agenesis of the olfactory bulbs (7/8), hypoplastic or absent lacrimal glands (11/14), hypoplastic parotid glands (12/14), and white matter signal anomalies (7/13).CONCLUSIONS:In the appropriate clinical context, bilateral agenesis or hypoplasia of the semicircular canals or both, associated with an enlarged vestibule and a cochlear deformity, strongly suggests a diagnosis of Waardenburg syndrome linked to a SOX10 mutation.
    American Journal of Neuroradiology 12/2012; · 3.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Management of bone and joint infections in children associates early appropriate antibiotic therapy against Staphylococcus aureus and Kingella kingae and, if necessary, surgical drainage of abscess or septic arthritis. In 2007, the Paediatric Infectious Diseases Group of the French Society of Paediatrics (GPIP) proposed guidelines for antibiotherapy in acute and non-complicated cases, with an intravenous therapy during 4 to 7 days followed by oral therapy during 3 weeks.
    Archives de Pédiatrie 09/2011; 18(9):1016-8. · 0.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Brain iron deficiency has been supposed to be involved in the pathophysiology of ADHD. Available studies assessing iron in ADHD are based on serum ferritin, a peripheral marker of iron status. To what extent serum ferritin correlates with brain iron (BI) is unclear. The main aim of this study was to compare BI, estimated with magnetic resonance imaging (MRI) in the putamen, pallidum, caudate, and thalamus, between children with and without ADHD. The secondary aim was to assess the correlation between serum ferritin and BI levels. Thirty-six children (18 with and 18 without ADHD, the latter including nine healthy controls and nine psychiatric controls) completed MRI and blood sampling. Brain iron levels were estimated by imaging T2*. Children with ADHD showed significantly lower estimated BI in right and left thalamus compared to healthy controls. Estimated BI did not differ significantly between children with ADHD and psychiatric controls. Children with ADHD had significantly lower levels of serum ferritin than healthy as well as psychiatric controls. Serum ferritin and T2* values did not correlate significantly in most regions. Low iron in the thalamus may contribute to ADHD pathophysiology.
    The World Journal of Biological Psychiatry 05/2011; 13(3):223-31. · 3.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ano-rectal trauma is common in motor vehicle accidents involving children. Inadequate initial assessment of the extent of lesions may be life threatening. We describe two cases where children were struck by buses that subsequently rolled over them in the prone position, resulting in ano-rectal and gluteal muscle wrenching. The first patient was inadequately assessed. Initial management did not include a diverting stoma, leading to life-threatening necrosis and septic shock. The second benefitted from our previous experience and recovery was uneventful. The distinctive mechanism of trauma in true gluteal muscle and anal canal wrenching is discussed. Gluteal muscle, anal canal and rectal wrenching as a result of rolling force from a motor vehicle is a very serious condition requiring immediate intestinal diversion with a stoma. Immediate repair may be attempted at the same time as stoma creation if the patient is stable. Broad-spectrum antibiotics and close wound monitoring are necessary to avoid muscle necrosis and serious complications.
    Pediatric Surgery International 03/2011; 27(10):1135-9. · 1.22 Impact Factor
  • Archives de Pédiatrie 01/2011; · 0.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Management of bone and joint infections in children associates early appropriate antibiotic therapy against Staphylococcus aureus and Kingella kingae and, if necessary, surgical drainage of abscess or septic arthritis. In 2007, the Paediatric Infectious Diseases Group of the French Society of Paediatrics (GPIP) proposed guidelines for antibiotherapy in acute and non-complicated cases, with an intravenous therapy during 4 to 7days followed by oral therapy during 3weeks.
    Archives De Pediatrie - ARCHIVES PEDIATRIE. 01/2011; 18(9):1016-1018.
  • Archives De Pediatrie - ARCHIVES PEDIATRIE. 01/2011; 18(3):311-312.
  • Archives de Pédiatrie 01/2011; 18(3):311-2, 338-41. · 0.36 Impact Factor
  • SOFCOT Société Française de Chrirugie Orthopédique et Traumatologique, Paris; 10/2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess the feasibility of magnetic resonance imaging (MRI) enhanced with ultrasmall superparamagnetic particles of iron oxide (USPIO) for assessing excitotoxic brain lesions in an experimental model of neonatal periventricular white matter (PWM) lesions. Brain lesions were induced by intracerebral injection of ibotenate in 14 newborn rats. Pre- and post-USPIO T2-weighted MRI was performed in seven of them (group A) and in five control newborns (group C). In seven newborns with induced cerebral lesions, USPIO-enhanced MRI was not performed (group B). We compared the signal intensity of the lesion to the contralateral unaffected brain (lesion-to-brain contrast, LBC) and the lesion signal-to-noise ratio (SNR) before and after USPIO injection. MR imaging was correlated with histology. USPIO injection significantly (P<0.05) decreased LBC and SNR of brain lesion but induced no changes in normal controls. The densities of macrophages and iron-laden cells were higher on the lesion side than on the contralateral side (P<0.05). Neither lesion size nor the surrounding macrophage infiltrate was significantly different between groups A and B. Post-USPIO T2-weighted MRI demonstrated negative enhancement of neonatal excitotoxic brain lesion. USPIO injection does not appear to exacerbate brain lesions.
    European Radiology 09/2010; 20(9):2204-12. · 4.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recently, in a 4-month proof-of-concept trial, beneficial metabolic effects were reported in non-diabetic children with Berardinelli-Seip congenital lipodystrophy (BSCL); this information prompted us to hypothesize that long-term leptin-replacement therapy might improve or reverse the early complications of the disease in these patients. A 28-month trial was implemented in eight patients. Efficacy assessment was based on a decrease in serum triglyceride concentrations, and/or a decrease in liver volume and/or an increase in insulin sensitivity of at least 30% respectively. The response was defined as follows: total (3/3 positive criteria), partial (1 or 2/3), or negative (0/3). Anti-leptin antibodies were measured with a radiobinding assay, and a neutralizing effect was assessed in primary cultures of embryonic neurons incubated with an apoptotic agent (N-methyl-D-aspartate) and the patient serum, with or without leptin. A negative or partial response to treatment was observed in five of eight patients even when leptin dosages were increased. A displaceable leptin binding was detectable in all patients after 2 months of treatment. At 28 months, binding was higher in the patients with a negative response than in the total responders, and it paralleled both the increase in leptin dosage and serum leptin concentrations. Co-incubation of embryonic neurons with serum from two patients with a negative response inhibited the neuroprotective effect of leptin. Under leptin therapy, patients with BSCL may develop a resistance to leptin, which could be partly of immunological origin, blunting the previously reported beneficial effects.
    European Journal of Endocrinology 03/2010; 162(6):1083-91. · 3.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Radiological investigation is frequently undertaken to assess the aetiology of sensorineural hearing loss (SNHL). To establish the CT measurements of the normal cochlea in children and to determine radiological criteria correlated with SNHL. A retrospective study of temporal bone CT performed in 159 children, age range from 3 days to 16 years between February 1999 and July 2004. A control group (n = 88) comprised children without SNHL; the SNHL group comprised 71 children. The width of the second turn of the cochlea (CW), the cochlear height (CH), and the width of the bony canal for the cochlear nerve (WCN) were measured on a reference plane containing the modiolus, the posterior semicircular canal, the footplate, and the stapes arch. Width of the canal measurements <or=1.7 mm or >or=2.5 mm supported the diagnosis of SNHL with a specificity of 97% and 91%, respectively. Cochlear width was found to be significantly smaller in the SNHL group (5.61 +/- 0.51 mm) than in the control group (5.75 +/- 0.31 mm, P < 0.02), a size <5.4 mm being highly suggestive of SNHL with a specificity of 90%. No significant variations of all measurements were found with age. Appropriate measurements of WCN and CW are highly correlated with SNHL.
    Pediatric Radiology 12/2009; 40(3):275-83. · 1.57 Impact Factor
  • Pediatric Radiology 07/2009; 39 Suppl 3:414-21. · 1.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To provide normal magnetic resonance imaging (MRI) reference biometric data of the fetal brain, to evaluate reproducibility and gender effect, to compare the two cerebral hemispheres and to compare MRI with ultrasonographic biometry, in a large cohort. Normal cerebral fetal MRI examinations were collected prospectively and several parameters were measured: the supratentorial space (bone and cerebral fronto-occipital and biparietal (BPD) diameters), the length of the corpus callosum (LCC), the surface area, height and anteroposterior diameter of the vermis, the transverse cerebellar diameter (TCD) and the anteroposterior diameter of the pons. We evaluated the interobserver reproducibility of measurements and the possible gender effect on measurements of bone BPD, TCD and LCC. We compared right and left hemispheres, right and left atria and ultrasound and MRI measurements. The study included 589 fetuses, ranging from 26 to 40 weeks. Normal values (from 3(rd) to 97(th) percentile) are provided for each parameter. Interobserver agreement was excellent, with an intraclass correlation coefficient (ICC) > 0.75 for many parameters. The gender effect was evaluated in 372 cases and did not reveal any clinically meaningful difference. Comparison between the right and left cerebral hemispheres and between the right and left atria did not reveal any meaningful differences. Ultrasound and MRI measurements of BPD and TCD were compared in 94 cases and 48 cases, respectively, and the agreement was excellent (ICC = 0.85). We present new reproducible reference charts for cerebral MRI biometry at 26-40 weeks' gestation, from a large cohort of fetuses.
    Ultrasound in Obstetrics and Gynecology 02/2009; 33(2):173-81. · 3.56 Impact Factor

Publication Stats

1k Citations
180.50 Total Impact Points

Institutions

  • 1996–2011
    • Hôpital Universitaire Robert Debré
      • Service d’Imagerie Pédiatrique
      Lutetia Parisorum, Île-de-France, France
  • 2008
    • Assistance Publique – Hôpitaux de Paris
      Lutetia Parisorum, Île-de-France, France
  • 2006
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
  • 2004–2006
    • Université de Technologie de Compiègne
      Compiègne, Picardie, France
  • 1995–1996
    • Université René Descartes - Paris 5
      Lutetia Parisorum, Île-de-France, France