This test is most commonly done on babies. It checks for problems from premature birth. It may be used to check problems in the brain and ventricles in babies up to about 18 months old.
Ultrasound waves can't pass through bones. So an ultrasound to check the brain can't 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 it can be done on adults after the skull has been opened with surgery. In adults, the test may be done to see brain masses during brain surgery.
Cranial ultrasound for babies
The test looks for possible problems of premature birth, such as:
- Periventricular leukomalacia (PVL). PVL is a condition in which the brain tissue around the ventricles is damaged. This may be caused by a lack of oxygen or blood flow to the brain that may have occurred before, during, or after birth.
- Bleeding in the brain. This includes intraventricular hemorrhage (IVH).
IVH is more common in premature babies than in full-term babies. When it occurs, it most often happens in the first 3 to 4 days after birth. Most cases of IVH can be found with cranial ultrasound by the first week after birth. But PVL can take several weeks to detect. If PVL is suspected, cranial ultrasound may be repeated 4 to 8 weeks after the birth. Several of these tests may be done to check areas in the brain.
Cranial ultrasound may also be done to check a baby's large or increasing head size. The test can also check for infection in or around the brain (such as from encephalitis or meningitis). Or it may check 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 find a brain mass. Because the test can't be done after the skull bones have fused, it is only done after the skull has been opened during brain surgery.
Why It Is Done
In babies, cranial ultrasound usually is done:
- As part of routine tests in premature babies. The test is used to find bleeding in the brain, such as intraventricular hemorrhage (IVH).
- To look for any problems or to look for periventricular leukomalacia (PVL).
- To screen for brain problems that may be present from birth. For example, it may look for congenital hydrocephalus.
- To check a head that may be growing too large.
- To look for infection or abnormal growths in or around the brain.
In adults, the test may be done during brain surgery to help find a brain mass.
How To Prepare
You don't need to do anything special to prepare for this test.
If an older baby is having the test, it may help if the baby is a little hungry. You can feed your baby during the test. This may help calm your baby so he or she will hold still during the test.
How It Is Done
This test is done by a doctor who is an expert in imaging tests (radiologist). Or it may be done by an ultrasound technologist (sonographer) who works along with a radiologist. For a baby, the test may be done at the baby's bedside in the neonatal intensive care unit (NICU).
Your baby will lie on his or her back. The transducer is moved across the soft spot on top of the head. This spot is called the fontanelle. 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 screen.
For an adult, the test is done during brain surgery to help find a brain mass.
The test usually takes 15 to 30 minutes.
How It Feels
The test usually doesn't cause discomfort. The gel used for the test may feel cold on the skin unless it is warmed first.
The size and shape of the brain look normal.
The size of the brain's inner fluid chambers (ventricles) is normal.
Brain tissue looks normal. There are no signs of bleeding, suspicious areas (lesions), abnormal growths, or infection.
Bleeding in the brain may be present. This may be a sign of intraventricular hemorrhage (IVH). The test may be repeated to keep track of the bleeding or to look for problems caused by the bleeding.
Suspicious areas or lesions around the brain's ventricles may be seen. This may be a sign of periventricular leukomalacia (PVL).
The brain and ventricles may be enlarged from the buildup of too much cerebrospinal fluid (CSF). This may be a sign of hydrocephalus.
Abnormal growths may be present. This may be a sign of a tumor or cyst.
What Affects the Test
You or your baby may not be able to have the test, or the results may not be helpful, if:
- The baby does not stay still during the test.
- There is an open wound or recent surgical wound in the area being viewed.
What To Think About
- Ultrasound can't go through bone, so cranial ultrasound can be done only on babies whose skull (cranial) bones have not yet grown together. But duplex Doppler ultrasound can be done to check blood flow in the brain in children and adults. To learn more, see the topic Doppler Ultrasound.
- Periventricular leukomalacia (PVL) usually can't be found until several weeks after birth. For this reason, cranial ultrasound is generally done 4 to 8 weeks after birth. Cranial ultrasound may find suspicious areas in the brain that may or may not be PVL. Because of this, ultrasound testing may be repeated over several weeks. Babies with PVL or intraventricular hemorrhage (IVH) may develop normally. Or they may have disabilities. These include cerebral palsy and intellectual disability.
- MRI scanning may be done instead of cranial ultrasound to evaluate PVL or IVH in premature babies. To learn more, see the topic Magnetic Resonance Imaging (MRI) of the Head.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Sloan MA, et al. (2004). Assessment: Transcranial Doppler ultrasonography. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology, 62(9): 1468–1481. Also available online: http://neurology.org/content/62/9/1468.full.