Biomedical subjects
Publications and source records attributed to Pascale Sonigo.
INTRODUCTION: Fetal CT is helpful in the diagnosis of bony anomalies, particularly with 3D reconstructions. DISCUSSION: Because of the potential risks of irradiation, CT should not be performed before 32 weeks' gestation and should be restricted to a carefully selected group of patients.
INTRODUCTION: Prenatal investigations make it possible to follow up malformative intracranial cysts from their detection in utero through the postnatal period. By including those that will remain silent postnatally, precious information can be provided about their real natural history. DIAGNOSIS: Contrary to common belief, the vast majority of these lesions, if not associated with other fetal anomalies, are benign in nature, remain clinically silent, do not evolve or even frequently regress spontaneously. They are compatible with a strictly normal life, whether requiring postnatal treatment or not. TREATMENT: Surgery is rarely needed for the treatment of an evolving hydrocephalus or an expanding cyst. PROGNOSIS: Clinical outcome is not correlated with cyst volume or location. Prognosis, therefore, does not rely upon brain deformation or translation but rather more upon brain integrity. To establish a correct prognosis all efforts must therefore aim to precisely analyze the brain anatomy. In this respect, fetal MRI is mandatory. Although chromosomal anomalies are rarely associated with isolated intracranial cysts, karyotype study is necessary. CONCLUSION: The accuracy of diagnosis and prognosis depends mainly upon our ability to correctly interpret images, which in turn depends on the resolution of prenatal imaging and on experience. Median retrocerebellar fluid collections remain the most difficult to prognosticate, retrocerebellar cysts often being difficult to differentiate from mega cisterna magna and Dandy-Walker complex. In our hands, prenatal prognostication was correct in approximately 90% of the cases.
INTRODUCTION: Fetal brain evaluation implies a perfect knowledge of the timing and characteristics of the developing nervous system during gestation. DISCUSSION: The first half of gestation corresponds to the neurulation, differentiation of primary cerebral vesicles, and neuronogenesis. The second half is characterized by the tremendous growth of the cerebral hemispheres and the settlement of gyral formation, while the ventricular system undergoes gradual narrowing. Gyral formation follows an invariable temporospatial schedule and is a good marker of fetal maturation. At the histological level, the fetal cortex displays transient developmental features, a superficial granular layer, and cells of Cajal-Retzius, which disappear at term. Neuroblasts formation has usually ceased by the 16th week of gestation, while neuronal migration continues until the extinction of the germinal layer. At this time, the remnant of the germinal layer constitutes, between the thalami and the caudate nucleus, an eminence of tightly packed cells, called the ganglionic eminence or germinal zone. They disappear by the age of 1 year.
INTRODUCTION: For the purposes of prenatal counselling and prognostication, it is essential to keep in mind the key diagnostic criteria allowing recognition of the diverse forms of spinal dysraphism. DIAGNOSIS: It is most crucial not to confuse lipomas and myelomeningoceles, the former carrying a usually favourable prognosis, while the latter a high risk of serious neurological deficits. In our experience, these two conditions can be clearly distinguished on prenatal ultrasound and by fetal biology. Lipomas are skin-covered, which explains the normality of the amniotic fluid and probably that of the intracranial content (no Chiari, no hydrocephalus). These features are distinct from those observed in the case of myelomeningoceles. The distinction between a lipoma and a meningocele is more difficult. The prenatal ultrasound presentation of many lipomas actually resembles that of a meningocele. In a few cases, the diagnosis of lipoma can, however, be suspected by the presence of an abnormally thick skin covering and intradural echoic structures that evoke a low-lying cord. CONCLUSIONS: However, the consequences of confusing a lipoma and most of the other types of occult dysraphism are minimal. Most of these lesions carry a favourable outcome.
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