乳幼児の水頭症における脳血流循環障害 : :MNUの経胎盤投与で作製したrat先天性水頭症および臨床症例による検討
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Dysfunction of the central nervous system during the increased intracranial pressure IS based on the impaired cerebral hemodynamics. In hydrocephalus during infancy, socalled periventricular sponginess is formed in its early stage during the ontogenetically critical period of myelination and cortical maturity. This peculiar pathological change had been supposed to predispose the dysfunction of microcirculation of developing brain. Yet, few studies had been done on the cerebral blood flow (CBF) in hydrocephalus during infancy. This study was aimed to clarify the pathophysiology of the reduction of cerebral blood flow in hydrocephalus during infancy correlating with the experimental and clinical findings. Experimental congenital hydrocephalus was induced in Sprague-Dawly rats by transplacental administration of N-methyl N-nitrosourea (MNU). Postnatal changes of CBF was assessed by the hydrogen clearance method. Microangioarchitecture was studied both by India ink injection method and resin-cast method under the light and the scanning electron microscope. In ten children with hydrocephalus, CBF was assessed with N-isopropyl-p- [<123>^I] iodoamphetamine single photon emission CT (IMP-SPECT), and correlated with the findings on X-ray CT. Experimentally, controls showed high CBF value which further increased postnatally. On the contrary, in MNU-induced hydrocephalus, CBF value reduced progressively up to 27.5 % of that of controls in the acute stage of hydrocephalus in the first postnatal week. Later than the second postnatal week; in the chronic stage, it regained to 65 % of controls. Microangioarchitecture of the brain in hydrocephalic rats showed the reduction of arteries; perforating and cortical branches dominantly in the periventricular white matter, and the relative increase of the precapillary anastomotic channels. In clinical hydrocephalus during infancy and early childhood, IMP-SPECT revealed the poor distribution of the CBF in periventricular white matter in all, and in frontal cortex in 20 % of patients. Dynamic analysis of SPECT suggested the tissue-reversibility of those ischemic leisons. Ventricular shunting recovered the CBF distribution pattern in 70 % of patients within two weeks. In conclusion, the progressive reduction of CBF was demonstrated dominantly in the periventricular white matter in hydrocephalus during infancy. The reduction of CBF is correlated with the impaired microcircualtion such as the reduction of capillaries and the increase of the precapillary shunting. Deranged microcirculation is predisposed by the sponginess of periventricular white matter caused by hydrocephalus, which relates to the progressive destruction of the developmentally vulnerable brain tissue during the critical period of myelination and cortical maturity.
- 神戸大学の論文
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- 乳幼児の水頭症における脳血流循環障害 : :MNUの経胎盤投与で作製したrat先天性水頭症および臨床症例による検討