What is hydrocephalus?
Hydrocephalus is a condition in which there is excessive fluid in and around the brain. It occurs from a lack of absorption, blockage of flow, or overproduction of the cerebral spinal fluid (CSF) that's made inside the ventricles (fluid-filled areas) of the brain and disperses from the ventricles around the brain and spinal cord. This may result in a buildup of fluid that can cause the pressure inside of the head to increase. In a child, this causes the bones of the skull to expand and separate to a larger-than-normal appearance.
What causes hydrocephalus?
Hydrocephalus occurs in approximately one out of 500 births. The following are the primary reasons why hydrocephalus occurs:
Blockage of the CSF flow inside of the head
Problems absorbing CSF
Overproduction of CSF (rare)
Hydrocephalus can occur either as a condition present at birth (congenital), or it can be acquired later in life. When hydrocephalus is not related to a known genetic cause, it's thought that many factors, both genetic and environmental, contribute to the condition. In a small percentage of babies, a single gene defect on the X chromosome, or another chromosome, is responsible for the condition. If a child has been born with hydrocephalus not known to be caused by a single gene defect, the chance of it occurring in another child is 1 to 5 percent.
Causes of acquired hydrocephalus may include:
Bleeding inside the head
Abnormal blood vessel formation inside of the head
What are the symptoms of hydrocephalus?
The following are the most common symptoms of hydrocephalus in babies. However, each baby may experience symptoms differently. Symptoms may include:
A full or bulging fontanel (soft spot located on the top of the head)
Increasing head circumference (size)
Bulging eyes and an inability of the baby to look upward with the head facing forward
Prominent scalp veins
Sleepiness or less alert than usual
The symptoms of hydrocephalus may resemble other conditions or medical problems. Always consult your baby's physician for a diagnosis.
How is hydrocephalus diagnosed?
Hydrocephalus may be diagnosed before birth by prenatal ultrasound, a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. In many cases, hydrocephalus doesn't develop until the third trimester of the pregnancy and, therefore, may not be seen on ultrasounds performed earlier in pregnancy.
The diagnosis of congenital hydrocephalus may be made at birth and after diagnostic testing. During the examination, the physician obtains a complete prenatal and birth history of the baby. He or she may also ask if there's a family history of hydrocephalus or other medical problems. The physician will also ask about developmental milestones in older babies since hydrocephalus can be associated with developmental delay. Developmental delays may require further medical follow-up for underlying problems.
The baby's head may appear larger than normal. A measurement of the circumference of the baby's head is taken and compared to a scale that can identify normal and abnormal ranges.
Diagnostic tests that may be performed to confirm the diagnosis of hydrocephalus include:
Ultrasound. This diagnostic procedure uses sound waves to create an image of an internal portion of the body and can be used to determine the size of the ventricles in the womb and in neonates.
Magnetic resonance imaging (MRI). This diagnostic procedure uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within the body.
Computed tomography (CT) scan. This diagnostic imaging procedure uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.