Neonatal germinal matrix hemorrhage/intraventricular hemorrhage (GMH/IVH) is the most common form of intracranial hemorrhage in preterm infants, and an important cause of long-term morbidities among survivors of neonatal intensive care. In its least severe form, the hemorrhage may be restricted to the germinal matrix area or subependymal zone. However, it frequently extends beyond the germinal matrix into the cerebral ventricles, following rupture of the germinal matrix hemorrhage into the ventricular space.
Germinal matrix hemorrhage/intraventricular hemorrhage occurs most frequently among preterm infants. Its incidence decreases as gestational age and birth weight increase. Because of improvement in perinatal and neonatal care, the incidence of GMH/IVH has decreased over the past several decades. However, this decline is of a lesser extent than that in neonatal mortality. Approximately 3 decades ago, GMH/IVH was noted in 45% of very low–birth-weight (VLBW) infants and in greater than 60% of those with birth weight of 750 grams or less. By the early 1990s, the incidence of GMH/IVH decreased to 30% of VLBW infants, and to 40% among the extremely low–birth-weight (ELBW) survivors, and by the mid 1990s had decreased further to 24%. Since that time, however, the incidence has remained static, remaining about 25% among all VLBW infants based upon data from the Vermont Oxford Network database (Fig. 61-1A). The more severe hemorrhages, grades III and IV, occur in 12% to 17% of ELBW infants and in as high as 20% of those with birth weight of 750 grams or less (Fig. 61-1B). These severe hemorrhages occur in 17% to 28% of those born at 22 to 26 weeks’ gestation and in 9% to 14% of those 27 to 32 weeks’ gestation.
A: The incidence of all grades of IVH, and individual IVH grades, in the Vermont Oxford Network database from 2011 to 2015, stratified by year. B: The incidence of all grades of IVH, and individual IVH grades, in the Vermont Oxford Network database from 2011 to 2015, stratified by birth weight. GMH, germinal matrix hemorrhage; IVH, intraventricular hemorrhage.
PATHOGENESIS AND RISK FACTORS
The pathogenesis of GMH/IVH is complex and involves multiple risk factors and disorders, with biochemical, inflammatory, and hemodynamic alterations and predisposing to the development of hemorrhage. Ultimately, the mechanisms for predisposition to hemorrhage, and the relationship among GMH/IVH and white matter and neuronal injury may be linked to the generation of free radicals, reactive oxygen and nitrogen species, and gene-environment interactions.
Hemorrhage originates in the germinal matrix which is a prominent structure in the preterm brain during the second and early third trimesters that subsequently undergoes involution as gestation reaches term. The germinal matrix structure contains neuronal precursor cells prior to 20 weeks ...