Hydrocephalus is a condition in which excessive amounts of cerebrospinal fluid (CSF) accumulate in the brain. This can cause pressure that injures the brain tissues. Hydrocephalus is believed to affect one in 500 children, according to the National Institutes of Health (NIH). Adults over age 60 also are especially vulnerable to this condition.

Hydrocephalus is either present at birth (congenital) or develops sometime after birth as a result of injury or illness (acquired). The two major types include:

• Communicating. Occurs when CSF flow is blocked after the fluid leaves the brain cavities.
  
  
• Noncommunicating. Also known as obstructive hydrocephalus, it occurs when CSF flow in the brain is blocked at one or more of the pathways through which the CSF circulates.

Medical scientists do not fully understand what causes hydrocephalus. Many cases of congenital hydrocephalus are believed to result from a combination of genetic factors and developmental problems, such as exposure of the fetus to an environmental factor that influences brain development. Acquired hydrocephalus usually results from injury or illness.

Symptoms of hydrocephalus vary from patient to patient. A patient’s age and the progression of the disease often play a significant role in the nature of the symptoms. For example, young children are especially likely to experience a pronounced increase in skull circumference. Meanwhile, older patients may experience dementia, balance and coordination problems and personality changes.

Several techniques can be used to diagnose hydrocephalus. These include imaging tests of the brain, intracranial pressure monitoring and spinal taps. Treatment usually consists of a surgical shunt system that diverts excess CSF from the brain to areas of the body where it can be absorbed. Medications and spinal tap procedures are also available to relieve pressure caused by excess CSF.

In most cases, hydrocephalus cannot be prevented. This is especially true of congenital hydrocephalus. However, people can take certain steps to reduce the risk of acquired hydrocephalus (e.g., wearing a helmet when riding a bicycle).

The prognosis for patients with hydrocephalus varies, but prompt treatment is essential to improve the odds of a positive long-term outcome.