Diagnostic ultrasound ( PDFDrive )

1582 PART V Pediatric Sonography
A
B
C
D
FIG. 46.8 Serial Imaging in a Neonate With Perinatal Hypoxic Ischemic Injury Treated With Therapeutic Hypothermia. (A) and (B) Initial
ultrasound study shows diffuse brain edema with increased echogenicity of the cerebral white matter, accentuated corticomedullary differentiation,
and slitlike ventricles. Anterior cerebral artery Doppler shows a resistive index (RI) value of 0.61. (C) and (D) Follow-up imaging shows normalization
of the B-mode imaging indings after completion of hypothermic therapy and a normal RI value of 0.75. These indings matched the normal neurologic
examination indings.
in RI during graded anterior fontanelle compression is a strong
predictor of ICP and can help predict the need for shunt placement.
his technique has also been used successfully to evaluate
intracranial compliance in young children with craniosynostosis
before surgical repair. 57
According to the Monro-Kellie hypothesis, the volume of
brain, cerebrospinal luid (CSF), blood, and other intracranial
components is constant. 58 During graded fontanelle compression
in normal infants, CSF or blood can be readily displaced to
compensate for the small increase in volume delivered by compression
of the anterior fontanelle, causing no increase in ICP. In
infants with hydrocephalus, however, the increase in intracranial
volume with fontanelle compression is translated into a transient
increase in ICP and an acute increase in arterial pulsatility
resulting in an increased RI (Fig. 46.12). Serial examinations
using this technique can follow an individual infant’s ability to
compensate for minor changes in intracranial volume, providing
a noninvasive, indirect measure of intracranial compliance 59
(Fig. 46.13).
Karl-Heinz Deeg and his group showed that calculating the
ratios of the peak systolic low velocity, EDV, and time average
low velocity measured in the intracranial and extracranial
carotid arteries (I/E ratio) can serve as an additional helpful
method for semiquantitative estimation of ICP. Slightly increased
ICPs below 20 cm H 2 O were linked to an increase of the I/E
ratio above 1, while the RI values remained unchanged. ICP
increases above 20 cm H 2 O lowered the I/E ratio signiicantly
below normal values of 0.8, while the RI values increased. he