Hydrocephalus (hy-dro-SEF-a-lus) is a condition that occurs when there is too much fluid inside the skull. The excess fluid inside the skull often creates pressure on the brain and may result in mental and physical handicaps.
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Why Is the Baby's Head So Big?
When Liz saw her baby brother in the hospital nursery, she was upset by his appearance. His head seemed huge. The doctor explained that John had hydrocephalus, or too much fluid within his skull. Because he was a newborn, the bones in his head had not yet grown together, allowing his head to expand with the pressure caused by the extra fluid. The doctor warned Liz's family that John's brain might have been squeezed and damaged by the excess fluid, but that it was too soon to tell for sure.
What Is Hydrocephalus?
Hydrocephalus refers to fluid buildup in and around the brain. The term comes from two Greek words: "hydro" meaning "water," and "cephalie" meaning "brain." Hydrocephalus often is called "water on the brain," but the brain and spinal cord are actually bathed in cerebrospinal fluid (CSF). CSF is a mixture of water, protein, sugar, and minerals that is made by the tissues lining the inside of the brain to cushion and protect it.
The brain contains four cavities, or spaces, called ventricles (VEN-trikuls). CSF normally flows through the ventricles, through tiny openings at the base of the brain, over the brain's surface, and around the spinal cord. Normally, the pressure exerted on the brain by CSF is kept fairly constant because excess CSF is reabsorbed into the bloodstream.
People develop hydrocephalus when the flow of CSF is blocked (obstructive hydrocephalus) or when it cannot be reabsorbed (communicating hydrocephalus). In both cases, CSF accumulates and the extra pressure squeezes the brain and disrupts blood flow to the brain. Without the oxygen and sugar that blood carries, the brain cannot function properly. Over time, blood vessels and nerve cells are damaged, resulting in problems with learning, thinking, and moving. The severity of hydrocephalus varies from person to person.
What Causes Hydrocephalus?
The cause of hydrocephalus often is unknown, but in many cases a cause can be found. Congenital hydrocephalus means that a person is born with the condition, and it affects about 1 in 1,000 babies. It may occur because the brain did not develop properly or because the fetus developed a viral or protozoan infection, such as rubella (German measles), herpes, cytomegalovirus, or toxoplasmosis. Spina bifida is a congenital disorder in which there is an opening in the spinal cord and spinal column, and at least 80 percent of babies with spina bifida also develop some degree of hydrocephalus.
In infants, children, and adults, brain tumors can cause hydro-cephalus by blocking the flow of CSF. Hydrocephalus also can be caused by meningitis, an infection of the linings of the brain and spinal cord, and by bleeding in the brain because of a stroke * or a head injury. Infants born very prematurely frequently experience bleeding in the ventricles of the brain, which often leads to hydrocephalus. Hydrocephalus is less common in adults.
How Is Hydrocephalus Treated?
Babies suspected of having hydrocephalus are watched closely. John's head kept getting bigger and ultimately his doctor used a CT scan * and an MRI * to examine his brain.
Some forms of hydrocephalus require no treatment, but most, like John's, require surgery. The surgeon placed a device called a shunt in John's brain to drain the excess CSF. Shunts are thin flexible tubes that are placed through the skull and drain some of the excess CSF into the bloodstream or the abdomen to be reabsorbed by the body. This procedure relieves pressure on the brain, but it does not cure the brain damage that has occurred already.
* stroke may occur when a blood vessel bringing oxygen and nutrients to the brain bursts or becomes clogged by a blood clot or other particle. As a result, nerve cells in the affected area and the specific body parts they control do not properly function.
* CT scans or CAT scans are the short names for computerized axial tomography, which uses computers and x-rays to view cross sections inside the body.
* MRI means magnetic resonance imaging, which uses magnets to view inside the body.
Most babies born with hydrocephalus live if they receive treatment, but 60 percent of those babies have mental and physical handicaps. Liz's baby brother John was lucky. He was among the 40 percent of children born with hydrocephalus whose mental and physical abilities are unaffected.
Toporek, Chuck, and Kellie Robinson. Hydrocephalus: A Guide for Parents, Families, and Friends. O'Reilly and Associates, 1999.
The U.S. National Institute of Neurological Disorders and Stroke posts a
fact sheet about childhood hydrocephalus at its website.
Hydrocephalus Association, 870 Market Street, Suite 955, San Francisco,
Association for Spina Bifida and Hydrocephalus, 42 Park Road,
Peterborough, PEI 2UQ, England.