解剖学と生理学: 現在の研究
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概要

Cerebral Venous Malformation as a Cause of Neonatal Intra-Ventricular Haemorrhage and Unexplained Infant Subdural Haemorrhage

David Talbert*

An Intra-ventricular Haemorrhage (IVH) is a bleeding into the brain’s ventricular system. Most intra-ventricular haemorrhages occur in the first 72 hours after birth. They originate in a layer of tissue (Germinal Matrix), under the lining of the ventricles (Ependymal), while it is in the process of manufacturing neurons and glia. This has normally regressed by term but may still be active in premature infants. Pathological investigations have found accumulations of peri-venous plasma and blood suggesting that excessive cerebral venous pressure has disrupted vessels, initiating the intra-ventricular bleeding observed. This has led to unsuccessful searches for evidence of A-V shunts within the developing cerebrum, or loss of auto regulation in arterioles, producing excessive cerebral venous hypertension. An alternative mechanism , reported here, is of venous rather than arterial origin; that high venous pressure results from inadequate venous drainage. Forcing increasing cerebral flow through inadequate venous vasculature requires increasing cerebral venous pressure. This is particularly significant at birth when the brain is suddenly stimulated to widespread activity which requires increased blood flow. This would explain why this disorder occurs shortly after birth. However, if rising cerebral pressure is insufficient to cause damage at birth, the infant may survive with a chronically high cerebral venous pressure. Then, minor stresses such as short falls, vomiting in pyloric stenosis, violent coughing, etc., may provide sufficient extra pressure to initiate haemorrhaging. In the embryo the pattern of arteries is pre-programmed, but veins climb gas gradients and their normal patterns are quite variable. Neonatal intra-ventricular haemorrhage is typically highly asymmetrical, and a typical inappropriate venous pattern is described. Recognition of inadequate venous patterns may not benefit the infant itself, but may protect any siblings from loss of home and parents.