Intraventricular Hemorrhage and Posthemorrhage Hydrocephalus

KEY POINTS

• 1.

  Very-low-birthweight infants are at risk of spontaneous germinal matrix–intraventricular hemorrhages (GM-IVHs).

• 2.

  GM-IVHs usually originate within the subependymal germinal matrix lining the ventricles and progress outwards into the ventricles. IVH occurs most frequently during the first 72 hours after birth.

• 3.

  A subset of infants with IVH develop periventricular hemorrhagic infarction, posthemorrhagic ventricular dilatation, and posthemorrhagic hydrocephalus (PHH).

• 4.

  Posthemorrhagic ventricular dilatation is noted in 30% to 50% of infants with IVH of grade III or IV and can damage the surrounding white matter due to increased pressure. One-third of these infants recover, but others require intervention.

• 5.

  The definitive treatment of PHH is usually the placement of a ventriculoperitoneal shunt, where the catheter has a proximal end in the ventricular system of the brain that is connected to a valve underneath the skin to control cerebrospinal fluid flow. Several other treatment modalities are being investigated.

Introduction

Premature infants with a birth weight <1500 g (very low birth weight infants) are at risk of spontaneous germinal matrix–intraventricular hemorrhages (GM-IVHs). These hemorrhages usually originate within the subependymal germinal matrix lining the ventricles, ^, a highly vascularized region rich in neuronal-glial precursor cells in the periventricular regions in the developing brain, and can progress outward. The etiology of IVH is multifactorial, but as currently understood, it can be ascribed primarily to frequent, accentuated fluctuations in the cerebral blood flow and the fragile vasculature of the germinal matrix. A subset of infants with IVH develop periventricular hemorrhagic infarction and posthemorrhagic ventricular dilatation (PHVD). ^, The ventricular dilatation may reflect hydrocephalus ex vacuo from encephalomalacia in some and symptomatic progressive posthemorrhagic hydrocephalus (PHH) with increased intracranial pressure in others. ^, Despite all the improvement in the frequency of neonatal morbidities and mortality in the past 2 decades, the incidence if IVH has not changed. GM-IVH is associated with increased mortality and abnormal neurodevelopmental outcomes in the form of posthemorrhagic hydrocephalus, cerebral palsy, epilepsy, severe cognitive impairment, and visual and hearing impairment.

In this chapter, we review the pathophysiology of IVH and PHVD, outline the medical and surgical management, and discuss interventions for prevention of IVH. In addition to data from our own unpublished quality-improvement/outcome-monitoring studies, this chapter includes information from an extensive literature review of the PubMed, EMBASE, and Scopus databases. To avoid bias in identifying studies, keywords were short-listed a priori from anecdotal experience and PubMed's Medical Subject Heading (MeSH) thesaurus.

Incidence and Timing of GM-IVH

GM-IVH is seen most frequently in premature infants, and both the incidence and severity of hemorrhage are inversely related to birth weight and gestational age. The incidence of IVH is highest is extremely low birth weight infants, although this varies by center and ranges between 5% to 52% of grades 3 to 4 and 5% to 19% of grade 2, respectively. Overall, the incidence of some of form of IVH in very low birth weight infants ranges from 20% to 25%. IVH occurs most frequently during the first 72 days after birth; nearly 50% of all IVHs occur within the first 24 hours, 25% on the 2nd day, and 15% on the 3rd day.

Neuropathology

Normal Cerebrospinal Fluid Pathways

Cerebrospinal fluid (CSF) is normally produced in the ependyma and choroid plexus. It flows from the lateral ventricles and passes through the foramina of Monro and then into the third ventricle. From there, it travels down the aqueduct of Sylvius and into the fourth ventricle. It then leaves the ventricular system through the foramina of Luschka and Magendie, entering the subarachnoid space of the basal cisterns. The flow continues up over the cerebral convexities to the arachnoid granulations, where it is resorbed into the venous system by a pressure-dependent mechanism. These details are shown in Fig. 52.1 .