Chapter 22: IVH, PVL, and Hydrocephalus

I. Intensive care

1. Intraventricular hemorrhage

   1. Definition

      Intraventricular hemorrhages (IVH) are bleeds in the subependymal germinal matrix and ventricular system of the brain.

   2. Incidence

      Rates of IVH in very preterm or very low birthweight (VLBW) infants (<32 weeks' gestation or <1500 g) vary between 20% and 25%, with about 6% to 7% suffering from severe IVH (grade 3 or 4).

   3. Pathophysiology

      1. The germinal matrix, which is lining the lateral ventricles, is the site of glial and neuronal precursor cells and involutes by 34 gestational weeks. The rich microvasculature of this temporary structure is poorly supported by connective tissue and extremely fragile.

      2. In addition, cerebral circulation in the preterm infant is often pressure passive, ie, cerebral blood flow varies with systemic blood pressure, due to immature cerebrovascular autoregulatory mechanisms. Any disturbance in cerebral blood flow or an increase in cerebral venous pressure can lead to rupture of the capillary network with bleeding in the germinal matrix and possible extension into the ventricular system.

      3. Venous infarction in the periventricular white matter area (periventricular hemorrhagic infarction [PVHI]) may follow secondary to impaired drainage and thrombosis of the medullary veins due to compression of distal terminal veins by an intraventricular hematoma.

      4. Inflammatory cytokines and reactive oxygen species are also important mediators in the mechanisms of microvascular disruption, cerebral blood flow dysregulation, and periventricular reperfusion injury.

      5. Finally, obstruction of cerebrospinal fluid (CSF) flow can lead to progressive ventricular dilation (see the Hydrocephalus section) with pressure-induced infarction of adjacent white matter and subsequent atrophy.

   4. Risk factors

      1. The risk of IVH and level of severity increase with lower gestational age and lower birthweight.

      2. Risk factors are related to conditions that can lead to either fluctuating, increased or decreased cerebral blood flow or increased cerebral venous pressure.

      3. They are also associated with systemic inflammation.

      4. Antepartum conditions include

         • Absence of antenatal steroids administration

         • Maternal hemorrhage

         • Chorioamnionitis or maternal infections

      5. Peripartum conditions are

         • Requirement for neonatal transport

         • Vaginal delivery

         • Vigorous resuscitation

      6. Postnatal conditions include

         • Severe respiratory distress syndrome, asynchronous ventilator breathing pattern, hypoxemia, hypercarbia, hypocarbia, pneumothorax, pulmonary hemorrhage, patent ductus arteriosus, acidoses requiring sodium bicarbonate, hypotension requiring inotropes, hypertension, sepsis, and seizures.

      7. Furthermore, candidate genes that may modulate the risk for IVH due to their involvement in the processes of inflammation, hemostasis, or vascular stability are currently being investigated.

   5. Clinical presentation

      1. Signs and symptoms

         • 90% of IVH occur within the first 72 hours of life with progression over the following week. The majority of infants will be asymptomatic and diagnosed following screening cranial ultrasound.

         • Signs and symptoms may be subtle and include changes in level of consciousness, cardiorespiratory pattern (apnea, bradycardia, hypotension), movement quantity and quality, muscle tone, and eye position/movement. In severe cases, stupor and coma, a sudden drop in blood pressure, nonreactive pupils, decerebrate posturing, flaccidity, and seizures may be present. Distension of the anterior fontanelle or cranial sutures may also be observed.

         • Any unexplained decrease in hematocrit or failure to increase the hematocrit following blood transfusion should also raise the ...