Intraventricular Hemorrhage: An Update

Although the incidence of intraventricular hemorrhage (IVH) has decreased in recent years, the increasing survival rates for the smallest premature infants indicate that the lesion will continue to be a major problem in neonatal intensive care facilities. We review prenatal, perinatal, and postnatal variables that have been associated with enhanced risk of IVH and address some of the methodological limitations of previously reported studies. The neuropa-thology is characterized by bleeding into the subependymal germinal matrix, with subsequent rupture into the lateral ventricle. The pathogenesis of IVH relates to intravascular, vascular, and extravascular factors. Intravas-cular factors are those that relate primarily to control of blood flow and pressure in the microcirculation of the germinal matrix. Vascular factors relate to the microcirculation of the matrix, the site of initial bleeding. A maturation-dependent alteration of vascular integrity and a vulnerability of matrix vessels to injury appear important. Extravascular factors include those relevant to mesenchy-mal and glial support for matrix vessels and to local fibrino-lytic activity in the germinal matrix. Prognosis in the setting of IVH relates to the mechanisms of brain injury, the most important of which is pcriventricular hemorrhagic infarction, often inappropriately called grade IV IVH and often associated with subsequent motor and cognitive deficits. Prevention of IVH remains the most important goal. Prenatal interventions include prevention of premature birth, transportation of premature infants to a tertiary facility in utero rather than after birth, possibly prenatal administration of phenobarbital or vitamin K, and optimal management of labor and deliver. Postnatal interventions include careful newborn resuscitation, correction or prevention of major hemodynamic disturbances, and correction of abnormalities of coagulation. Postnatal pharmacological interventions that have been studied in detail include phenobarbital, indomethacin, ethamsylate, and vitamin E. No single agent among this group has been shown consistently to lead to a decrease in incidence and severity of IVH.