A cranial ultrasound makes use of sound waves. The reflected waves create images of the brain and inner fluid chambers. Cranial ultrasound is mostly conducted on babies to assess any complications stemming from premature births. For adults the test is conducted when the skull is surgically opened, this is because the sound waves cannot penetrate through bone. In the case of babies, the skull bones have not yet fused, the test can therefore be used on children up to the age of 18 months.
Premature births give rise to complications such as intraventricular hemorrhage (IVH), a condition where bleeding occurs in the brain. The lack of blood flow results in cell death and subsequent breakdown of the blood vessel walls, leading to bleeding. Another complication is periventricular leukomalacia (PVL), where brain tissue surrounding the ventricles gets damaged because of insufficient oxygen or blood flow reaching the brain, either before, during, or post delivery. IVH commonly affects premature babies more often than babies carried to full-term. It often develops within three to four days after the baby is delivered. Cranial ultrasound conducted on a newborn helps detect this condition as early as a week after birth. If PVL is suspected, repeated cranial ultrasound scans between the fourth and eight week after delivery may be required to accurately detect this condition. Children suffering from these conditions are at a high risk of developing disabilities ranging from mild learning disorders and cerebral palsy, to mental retardation. Cranial ultrasound is also used to scan for congenial brain problems such as congenial hydrocephalus. It is also used to look for any abnormal growths or infections in and around the brain.
The test needs no special preparation. However, for older babies, the child could be kept a little hungry so as to feed the child while the test is being conducted. This should help keep the child distracted and allow the mother to hold the baby still during the scan.
This test is conducted by a radiologist or a sonographer, or an ultrasound technologist. The test can be conducted at the child's bedside within the neonatal intensive care unit. The baby is made to lie face up, while the transducer is moved across the top of the head on the fontanelle, which is the soft membranous gap between the bones of the cranium. A video monitor displays images of the brain and the inner chambers or ventricles.