History: 4 day old baby with apnea
The germinal matrix is the site of proliferating neuronal and glial precursors in the developing brain, which is located above the caudate nucleus in the floor of the lateral ventricle and caudothalamic groove. The germinal matrix contains a rich network of fragile thin-walled blood vessels. Hence the microcirculation in this particular area is extremely sensitive to hypoxia and changes in perfusion pressure. It is most frequent before 35 weeks gestation and is typically seen in very low birth-weight (<1500g) premature infants,because they lack the ability for auto regulation of cerebral blood flow. Increased arterial blood pressure in these blood vessels leads to rupture and hemorrhage into germinal matrix.
Germinal matrix hemorrhage has a grading system as follows:
- Grade I: Confined to caudothalamic groove
- Grade II: Extends into ventricle but does not expand it (see below for an example of intraventricular hemorrhage)
- Grade III: Fills and distends adjacent ventricle
- Grade IV: Parenchymal hemorrhage/edema/ischemia beyond germinal matrix