@1 year ago with 311 notes
#medical #embryology #neurology
Germinal matrix hemorrhage (GMH) in premature newborns.
The germinal matrix is a thick cellular layer of immature cells (neuronal and glial precursors) under the ependymal lining of the ventricles. It give rise to the neurons of the cerebral cortex during embryologic development.
The germinal matrix is exceptionally vascular with a network of thin fragile capillaries highly susceptible to injury by hypoxia. In early gestation, the germinal matrix lines the wall of the entire ventricular system, lying just beneath the ependyma, the thin membranous lining of the ventricular system.
After 12 weeks gestation, the germinal matrix begins to regress.
By 24 weeks, only the germinal matrix over the caudate nucleus persists.
By full term at 40 weeks, the germinal matrix no longer exists.
Thus hemorrhage of the germinal matrix is a disease of premature infants. It originates in the residual germinal matrix that overlies the caudate nucleus in the frontal horns of the lateral ventricles.
The normal germinal matrix is not visualized by US.
The hemorrhage starts usually between the thalamus and the caudate nucleus, adjacent to the foramina of Monro, and is frequently bilateral.
If it is large, it ruptures into the ventricles, flooding the lateral, third, and fourth ventricles (intraventricular hemorrhage - IVH). Blood then exits through the foramina of Luschka, causing subarachnoid hemorrhage. Thick clots along the ventral aspect of the brain stem may block the foramina of Luschka.
grade I : confined to the germinal matrix
grade II : intraventricular hemorrhage without ventricular dilatatation
grade III : intraventricular hemorrhage with ventricular dilatation
gade IV : GMH with intraventricular rupture and hemorrhage into the surrounding white matter