Cranial Ultrasound

Cranial ultrasound uses reflected sound waves to produce pictures of the brain and the inner fluid chambers (ventricles) through which cerebrospinal fluid (CSF) flows. This test is most commonly done on babies to evaluate complications of premature birth. In adults, cranial ultrasound may be done to visualize brain masses during brain surgery.

Ultrasound waves cannot pass through bones; therefore, an ultrasound to evaluate the brain cannot be done once the bones of the skull (cranium) have grown together. Cranial ultrasound can be done on babies before the bones of the skull have grown together or on adults after the skull has been surgically opened. It may be used to evaluate problems in the brain and ventricles in babies up to 18 months old.

Cranial ultrasound for babies

If an older baby is having the test, it may help to have the baby be a little hungry. The baby can be fed during the test, which will help the baby be comforted and hold still during the test.
Because ultrasound cannot penetrate bone, cranial ultrasound can be performed only on babies whose skull (cranial) bones have not yet grown together. However, duplex Doppler ultrasound can be done to evaluate blood flow and vessel spasms in the brain in children and adults.
Complications of premature birth include bleeding in the brain (intraventricular hemorrhage, or IVH) and periventricular leukomalacia (PVL). PVL is a condition in which the brain tissue around the ventricles is damaged, possibly from decreased oxygen or blood flow to the brain that may have occurred before, during, or after delivery. Both IVH and PVL increase a baby's risk of developing disabilities that may range from mild learning or gross motor delays to cerebral palsy or mental retardation.

IVH is more common in premature babies than in full-term babies. When it occurs, it most commonly develops in the first 3 to 4 days after birth. Most cases of IVH can be detected by cranial ultrasound by the first week after delivery. By contrast, PVL can take several weeks to detect. For this reason, cranial ultrasound may be repeated between 4 and 8 weeks after delivery if PVL is suspected. Several cranial ultrasound tests may be done to evaluate areas in the brain.

Cranial ultrasound may also be done to evaluate a baby's large or increasing head size, detect infection in or around the brain (such as from encephalitis or meningitis), or screen for brain problems that are present from birth (such as congenital hydrocephalus).

Magnetic resonance imaging (MRI) scanning may be done instead of cranial ultrasound to evaluate PVL or IVH in babies born prematurely.

Cranial ultrasound for adults

Cranial ultrasound may be done on an adult to help locate a brain mass. Because cranial ultrasound cannot be done once the skull bones have fused, it is only done once the skull has been surgically opened during brain surgery.