Decrease in pulsatile flow in the anterior cerebral arteries in infantile hydrocephalus.

The effect of ventriculomegaly with or without elevated intracranial pressure (ICP) on pulsatile flow in the anterior cerebral artery has been studied by a noninvasive Doppler technique in 11 infants with hydrocephalus. The cause of hydrocephalus was intraventricular hemorrhage in nine infants, Arnold-Chiari malformation in one, and bacterial meningitis in one. The pulsatility index (PI) (inversely related to pulsatile flow) was calculated from the systolic and diastolic amplitudes of flow in the anterior cerebral artery. All 11 patients with elevated PI had marked ventriculomegaly, and all but two had raised ICP. Four patients with massive ventriculomegaly and elevated ICP had maximal PI (ie, 1.00). The finding of elevated PI with ventriculomegaly and normal ICP, observed in two patients, suggested that ventriculomegaly is a more critical factor than ICP in the pathogenesis of the impaired flow. Treatment of ventriculomegaly in seven patients resulted in a decrease in PI. Of the four untreated patients, three died and one was not available for further study. Compromised flow in the anterior cerebral artery may be a sensitive barometer of impending ischemic injury with evolving ventriculomegaly, particularly following intraventricular hemorrhage. The PI may be a valuable parameter for the study of the mechanism of brain injury and for determination of optimal timing of corrective intervention.