Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery
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Comparative Study
Dandy-Walker malformation: prenatal diagnosis and prognosis.
The difficulty in prognosticating the clinical and intellectual outcome of fetuses presenting with a Dandy-Walker malformation (DWM) comes from the great variety of cystic, median, and retrocerebellar malformations that probably have nothing in common and the variability of the definitions given to these lesions. In addition, many of these lesions can mimic each other. A correct diagnosis cannot be made without a good quality MRI including sagittal views of the vermis and T2-weighted images. We limited the diagnosis of DWM to those malformations with all of the following features: 1) a large median posterior fossa cyst widely communicating with the fourth ventricle, 2) a small, rotated, raised cerebellar vermis, 3) an upwardly displaced tentorium, 4) an enlarged posterior fossa, 5) antero-laterally displaced but apparently normal cerebellar hemispheres, 6) a normal brain stem. If any one of the previous criteria were not met, the malformation was considered distinct from DWM. ⋯ We described two types of DWM. The most frequent is characterized by an isolated and partially agenetic vermis. This malformation is compatible with a normal life. The second type consists of a severely abnormally lobulated vermis and associated brain malformation. This malformation is always accompanied by mental retardation.
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Diastematomyelia, also termed split cord malformation, is a form of occult spinal dysraphism characterized by a cleft in the spinal cord. Prenatal diagnosis of this anomaly is possible by ultrasonography (US), and fetal MRI can be used to diagnose the type of diastematomyelia precisely. Diastematomyelia can be isolated or associated with other dysraphisms, segmental anomalies of the vertebral bodies, or visceral malformations (horseshoe or ectopic kidney, utero-ovarian malformation, and anorectal malformation). We present three cases of fetal diastematomyelia investigated using a multimodal prenatal work-up (US, MRI, 3D-CT). ⋯ The first case, detected at 20 weeks' gestation, had a lumbar meningocele. At 30 weeks' gestation, direct US visualization revealed the division of the spinal cord into two hemicords. This patient illustrates an isolated type II diastematomyelia with a favorable prognosis. The second case, detected at 22 weeks' gestation, presented with disorganization of bony process of the vertebral column with a midline echogenic bony spur, asymmetrical hemicords, and a foot malposition. Fetal MRI at 26 weeks' gestation and CT/3D reconstructed at 32 weeks' gestation confirmed a type I diastematomyelia with orthopedic malposition. The third case, detected at 22 weeks' gestation, presented with widening of the lumbar canal and scoliosis. Prenatal work-up (US, MRI) disclosed other visceral malformations (pelvic kidney), which led to the assumption of a complex polymalformative syndrome. The pregnancy was terminated. Fetopathologic examination disclosed even more visceral malformations (anal atresia and unicorn uterus).