Transcranial Color-Coded Doppler Ultrasonography
Object: Hydrocephalus is a common disease process. Transcranial color-coded Doppler (TCCD) ultrasonography is an accepted noninvasive method with which to quantify intracranial blood flow in adults and children. The authors studied the applications of TCCD ultrasonography and the alterations of the flow velocity of the cerebral arteries in children with hydrocephalus.
Methods: One hundred thirty-five children were divided into three groups: Group 1 comprised 40 infants with asymptomatic hydrocephalus who had well-functioning ventriculoperitoneal (VP) shunts; Group 2 comprised 10 children with symptomatic hydrocephalus who had malfunctioning shunts that were replaced; and Group 3 was a control group of 85 healthy infants. All patients underwent sequential measurements of cerebral blood flow (CBF) velocities (systolic and diastolic velocities) and resistivity index (RI). One group of patients underwent functional tests (compression of the anterior fontanelle and CO₂ vasoreactivity) to determine hemodynamic changes in cerebral circulation. A significant statistical change in RI measurements, end diastolic CBF velocity, and percentage of change in RI was shown in patients with malfunctioning shunts, and in infants with a well-functioning VP shunt vasomotor reactivity was severely reduced.
Conclusions: Transcranial color-coded Doppler ultrasonography can be used to perform follow-up assessments of normal and malfunctioning shunts in children with hydrocephalus; the functional tests are a noninvasive tool for evaluating the cerebral compliance and the cerebral autoregulation in infants with hydrocephalus. The autoregulatory capacity may partly or completely be lost in cases of long-term shunt-treated hydrocephalus, and loss of cerebral vasoreactivity may be responsible for long-term deficits commonly observed in children, which help explain some of symptoms related to slit ventricles.

The introduction of TCD ultrasonography by Aaslid, et al., in 1982 offered a portable, noninvasive means for measuring CBF velocity in the major intracranial vessels. Therefore, applications of this new technology increased considerably and included use in infants and children with hydrocephalus. The Pourcelot RI and the Gosling PI are the two most commonly used PIs in patients with hydrocephalus. Both were initially used to study cerebral circulation in hydrocephalus in 1982.

Cerebral TCCD ultrasonography, first performed in 1989, allows direct visualization at basal cerebral arteries and demonstrates CBF easily because of the color coding.

In infants, because both the anterior fontanelle and the temporal bone window can be used to assess the cerebral circulation, the circle of Willis arteries (the ACA, MCA, ICA, and PCA) can be easily insonated.

The purpose of our study was to determine prospectively how RI and velocity measurements, obtained using TCCD ultrasonography, are affected in children with long-term asymptomatic or malfunctioning shunts. To define better the CBF hemodynamic changes in hydrocephalus, functional tests (RI changes in response to fontanelle compression and to CO₂-inhaled vasomotor reactivity) were performed.