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, so an ultrasound to evaluate the brain cannot be done after 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 about 18 months old.
Cranial ultrasound for babies
Complications of premature birth include periventricular leukomalacia (PVL) and bleeding in the brain, including intraventricular hemorrhage (IVH). 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. 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 an intellectual disability.
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. In contrast, PVL can take several weeks to detect. For this reason, cranial ultrasound may be repeated 4 to 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).
Cranial ultrasound for adults
Cranial ultrasound may be done on an adult to help locate a brain mass. Because cranial ultrasound cannot be done after the skull bones have fused, it is only done after the skull has been surgically opened during brain surgery.
Why It Is Done
In babies, cranial ultrasound usually is only done:
In adults, cranial ultrasound may be done during brain surgery to help locate a brain mass.
How To Prepare
No special preparation is required before having this test.
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 to be comforted and to hold still during the test.
How It Is Done
This test is done by a doctor who specializes in interpreting imaging tests (radiologist) or by an ultrasound technologist (sonographer) who is supervised by a radiologist. For a baby, cranial ultrasound may be done at your baby's bedside in the neonatal intensive care unit (NICU). With the baby lying on his or her back, the transducer is moved across the soft spot (fontanelle) on top of the head. You may be asked to hold your baby during the test. Pictures of the brain and inner fluid chambers (ventricles) can be seen on a video monitor.
For an adult, cranial ultrasound is done during brain surgery to help find a brain mass.
A cranial ultrasound usually takes 15 to 30 minutes.
How It Feels
There is usually no discomfort involved with having a cranial ultrasound test. Unless the gel is first warmed to body temperature, it may feel cold when it is put on the skin.
There are no known risks linked with a cranial ultrasound test.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
What To Think About
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