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Child Neurology - part 4

Trong hydranencephaly, phần lớn hơn của cả hai bán cầu đại não và thể vân thể giảm xuống túi màng bao gồm các mô thần kinh đệm được bao phủ bởi màng não còn nguyên vẹn và bao gồm một khoang chứa đầy dịch não tủy rõ ràng. Thỉnh thoảng, dịch não tủy là đục và giàu protein. | In hydranencephaly the greater portions of both the cerebral hemispheres and the corpus striatum are reduced to membranous sacs composed of glial tissue covered by intact meninges and encompassing a cavity filled with clear CSF. Occasionally the CSF is opaque and protein rich. Basal portions of frontal temporal and occipital lobe are preserved together with scattered islands of cortex elsewhere. The diencephalon midbrain and brainstem are usually normal except for rudimentary descending corticobulbar and corticospinal tracts. The cerebellum can be normal hypoplastic or damaged 727 728 . In some cases the ependyma lining the covering membrane is intact the choroid plexus is preserved and the aqueduct is stenotic. Other patients have large bilateral schizencephalic clefts in which pia and ependyma are joined and they demonstrate other migration anomalies of fetal morphogenesis. In still other brains bilateral porencephalic cysts replace the parenchyma normally perfused by the middle and anterior cerebral arteries. The latter instances show pathologic evidence of a destructive lesion. Pathogenesis The pathology suggests at least four different pathogenetic mechanisms. Some authorities citing the presence of preserved ependyma and aqueductal stenosis in some cases have argued that hydranencephaly is a type of hydrocephalus that has run its course in utero. In other instances hydranencephaly can be the consequence of intrauterine infections or other gestational insults 728 729 . In other cases the condition can represent a genetically determined defect in vascular ontogenesis or can be the outcome of vascular occlusion of both internal carotid arteries or their main branches 727 730 . A proliferative vasculopathy with an autosomal recessive inheritance also has been described 731 . A few cases appear to be caused by defects in embryogenesis and subsequent cellular migration resulting in schizencephaly and cortical agenesis 314 . Clinical Manifestations Infants appear .