Hydrocephalus is a condition characterized by excessive fluid buildup in the brain. Although hydrocephalus was once known as "water on the brain," the "water" is actually cerebrospinal fluid (CSF) -- a clear fluid surrounding the brain and spinal cord. The extra accumulation of CSF causes the spaces in the brain, called ventricles, to expand. This expansion causes potentially harmful pressure on the tissues of the brain.
Understanding the Ventricular System and CSF
The ventricular system is made up of four ventricles connected by narrow pathways. Normally, CSF flows through the ventricles, exits into cisterns (closed spaces that serve as reservoirs) at the base of the brain, bathes the surfaces of the brain and spinal cord, and then is absorbed into the bloodstream.
CSF has three important life-sustaining functions:
- To keep the brain tissue buoyant
- To act as a cushion or "shock absorber"
- To deliver nutrients to the brain and remove waste
- To flow between the cranium and spine to compensate for changes in the amount of blood within the brain.
The balance between production and absorption of CSF is critically important. Ideally, the fluid is almost completely absorbed into the bloodstream as it circulates; however, there are circumstances that, when present, will prevent or disturb the production or absorption of CSF, or that will inhibit its normal flow. When this balance is disturbed, hydrocephalus is the result.
There are several different hydrocephalus types. These include:
- Congenital hydrocephalus
- Acquired hydrocephalus
- Communicating hydrocephalus
- Non-communicating hydrocephalus
- Hydrocephalus ex-vacuo (caused by stroke or injury)
- Normal pressure hydrocephalus.
It is difficult to know how many people have hydrocephalus and how many are diagnosed with it each year. This condition is believed to affect approximately 1 in every 500 children. At present, most of these cases are diagnosed prenatally, at the time of delivery, or in early childhood.
Symptoms of Hydrocephalus
Symptoms of hydrocephalus vary with age, disease progression, and individual tolerance to CSF.
In infancy, the most obvious sign of the condition is often a rapid increase in head circumference or an unusually large head size.
In older children and adults, symptoms may include
headache followed by:
- Vomiting
- Nausea
- Papilledema (swelling of the optic disk, which is part of the optic nerve)
- Downward deviation of the eyes (called "sunsetting")
- Problems with balance
- Poor coordination
- Gait disturbance
- Urinary incontinence
- Slowing or loss of development (in children)
- Lethargy
- Drowsiness
- Irritability
- Other changes in personality or brain function, including memory loss.
In order to diagnose hydrocephalus, the doctor will ask a number of questions and perform a physical exam to look for signs and symptoms of hydrocephalus. He or she may also recommend certain tests that can be used to diagnose the condition. These tests may include:
-
Ultrasound
-
Computed tomography scan (CT scan)
-
Magnetic resonance imaging (MRI)
-
Pressure-monitoring techniques.
Hydrocephalus is most often treated with the surgical placement of a shunt system. This system diverts the flow of CSF from a site within the central nervous system to another area of the body where it can be absorbed as part of the circulatory process. A limited number of patients are treated with an alternative procedure called third ventriculostomy. In this procedure, a small hole is made in the floor of the third ventricle, allowing the CSF to bypass the obstruction.
Prognosis for Hydrocephalus
The prognosis for patients diagnosed with hydrocephalus is difficult to predict, although there is some relationship between the cause of the patient's condition and the outcome of the condition. Prognosis is further complicated by the presence of associated disorders, the timeliness of diagnosis, and the success of treatment.
The symptoms of
normal pressure hydrocephalus usually get worse over time if the condition is not treated, although some people may experience temporary improvements.
If left untreated, progressive hydrocephalus is fatal, with rare exceptions. The parents of children with hydrocephalus should be aware that hydrocephalus poses risks to both cognitive and physical development. Treatment by an interdisciplinary team of medical professionals, rehabilitation specialists, and educational experts is critical to a positive outcome. Many children diagnosed with the disorder benefit from rehabilitation therapies and educational interventions, and go on to lead normal lives with few limitations.
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