Hydrocephalus
What is it?
Hydrocephalus is a condition in which an excessive amount of cerebrospinal fluid (CSF) accumulates in the brain. The pressure created by the excess fluid causes the normal spaces in the brain, called ventricles, to become enlarged. Another type of hydrocephalus, called normal pressure hydrocephalus, is characterized by enlarged ventricles, but no increase in CSF
pressure.
Who gets it?
Hydrocephalus can be congenital, meaning it is a condition that is present at birth. Hydrocephalus can also occur at any time after birth. This is called acquired hydrocephalus. Normal pressure hydrocephalus occurs mainly in the
elderly.
What causes it?
You may have heard hydrocephalus referred to as "water on the brain."
The fluid that builds up and causes hydrocephalus is not water, but cerebrospinal fluid (CSF). CSF is the clear fluid surrounding the brain and spinal cord and is produced in the ventricles of the brain. However, CSF normally drains to an area just inside the skull called the subarchnoid space, and is then absorbed into the bloodstream. If the fluid cannot drain, the ventricles become enlarged and put pressure on the brain tissue. Congenital hydrocephalus can be caused by either heredity or environmental influences. Children born with a birth defect called a neural tube defect (the neural tube that forms the spinal cord does not close completely) may develop hydrocephalus because the CSF accumulates on the brain. Environmental influences include infections acquired by the mother during pregnancy, such as syphilis, herpes, meningitis, encephalitis, or mumps.
Acquired hydrocephalus occurs any time after birth, and may be caused by injury, infection, or disease. Two types of hydrocephalus cause elevated pressures within the brain. When the build-up of fluid is caused by a blockage of the passages that connect the ventricles, preventing CSF from draining, it is called noncommunicating hydrocephalus. When fluid builds up because the tissue that absorbs CSF is damaged and fluid absorption cannot keep up with production, it is called communicating
CSF.
What are the symptoms?
The symptoms of hydrocephalus vary according to the child's age and how far the disease has progressed. The increased pressure in the brain squeezes the soft tissues, causing damage and distorting them. At first, an infant might become increasingly irritable. Because a very young infant's skull bones have not yet fused together, the first visible sign might be a bulge in the area between the skull bones called the soft spot, or fontanel. The build up of fluid keeps the soft spot from fusing together, which results in a gradual increase in head size. Without treatment, the infant will become increasingly lethargic. In older children, symptoms might include headache; nausea and vomiting; lethargy and drowsiness; vision problems caused by swelling of the optic disk (papilledema); a downward deviation of the eyes (sunsetting); balance, coordination, and gait problems; urinary incontinence; developmental delays; changes in personality; learning difficulties; and memory loss. Hydrocephalus is a cause of mental
retardation.
How is it diagnosed?
Hydrocephalus is diagnosed through a neurological evaluation and by using imaging techniques such as x-ray, computed tomography scan (CT), magnetic resonance imaging (MRI), ultrasound, or pressure-monitoring techniques. The doctor will look for any obstructions, and for changes in the brain tissue. A lumbar puncture, also know as a spinal tap, may be used to withdraw some cerebrospinal fluid (CSF) to check for bacterial infections that could be the
cause.
What is the treatment?
To treat hydrocephalus, doctors need to provide an alternate drainage path for the CSF. To do this, a device called a shunt is surgically implanted in the ventricles of the brain. A shunt is a flexible tube that runs from the brain, under the skin, to the abdominal cavity, where it is simply absorbed by the body. The shunt contains a one-way valve that lets fluid leave the brain when pressure becomes to high, but prevents the fluid from reversing and flowing back to the brain. Because shunts can sometimes become blocked or fail, the child's family must monitor the child and notify the doctor immediately if they notice any signs of hydrocephalus. Drugs can sometimes be used to slow the production of CSF and temporarily reduce pressure in the brain until a shunt can be inserted. These drugs include cetazolamide, furosemide, glycerol, digoxin, and isosorbide. In somecases of non-communicating hydrocephalus, where there is a blockage of the passages that connect the ventricles, doctors can make a direct connection between one of the ventricles and the drainage site inside the skull (the subarchnoid space), so the fluid can drain without a shunt. An alternative procedure called third ventriculostomy is used with a small number of patients. With this procedure, a small hole is made in the floor of the third ventricle. The CSF can bypass the obstruction by flowing through this hole. The success of treatment for hydrocephalus depends upon the cause, how quickly the condition is diagnosed, and whether there are any associated disorders. Early rehabilitative therapies and educational interventions help to ensure that a child with hydrocephalus has the best chance to live life with the fewest
limitations.
Self-care tips
In many cases, hydrocephalus cannot be predicted or prevented. However, some cases of hydrocephalus can be avoided by preventing or treating the infectious diseases that cause this condition.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
|
