Hydrocephalus is a build up of fluid inside the skull, leading to brain swelling. Hydrocephalus means "water on the brain."

Hydrocephalus is due to a problem with the flow of cerebrospinal fluid (CSF), the liquid that surrounds the brain and spinal cord.

CSF moves through pathways of the brain called ventricles. It also flows around the outside of the brain and through the spinal canal. Higher-than-normal amounts of CSF can occur in the brain if the flow or absorption of CSF is blocked, or if too much CSF is produced. The build up of fluid puts pressure on the brain, pushing the brain up against the skull and damaging or destroying brain tissues.

Myelomeningocele, a disorder involving incomplete closure of the spinal column, is strongly associated with hydrocephalus.

In young children, hydrocephalus may also be associated with the following conditions:

• Infections caught before birth
• Infections that affect the central nervous system (such as meningitis or encephalitis )
• Injury before, during, or after childbirth, including subarachnoid hemorrhage
• Congenital defects
• Tumors of the central nervous system

In older children, risks for hydrocephalus include:

• History of congenital or developmental defects
• Lesions or tumors of the brain or spinal cord
• Central nervous system infections
• Bleeding anywhere in the brain
• Injury

Hydrocephalus most often occurs in children, but may also occur in adults and the elderly.

The symptoms depend on the cause of the blockage, the person's age, and how much brain tissue has been damaged by the swelling.

In infants with hydrocephalus, CSF fluid builds up in the central nervous system, causing the fontanelle (soft spot) to bulge and the head to expand. Early symptoms may also include:

• Separated sutures
• Vomiting

Symptoms of continued hydrocephalus may include:

• Irritability, poor temper control
• Muscle spasticity (spasm)

Symptoms that occur later in the disease may include:

• Brief, shrill, high-pitched cry
• Decreased mental function
• Delayed development
• Difficulty feeding
• Excessive sleepiness
• Loss of bladder control (urinary incontinence)
• Slow growth (child 0-5 years)
• Slow or restricted movement

Symptoms in older babies and children may include:

• Changes in facial appearance and eye spacing
• Confusion or psychosis
• Crossed eyes
• Headache
• Loss of coordination
• Poor gait (walking pattern)
• Uncontrolled eye movements
• Vision changes
• Vomiting

When a health care provider taps fingertips on the skull, there may be abnormal sounds that indicated thinning and separation of skull bones. Scalp veins may appear stretched or enlarged.

Part or the entire head may be larger than normal. Enlargement is most commonly seen in the front part of the head. Head circumference measurements, repeated over time, may show that the head is getting bigger.

The eyes may look "sunken in." The white part of the eye may appear above the colored part of the eye, given the eyes a "setting-sun" appearance. Reflexes may be abnormal.

A head CT scan is one of the best tests for identifying hydrocephalus. Other tests that may be done include:

• Arteriography
• Brain scan using radioisotopes
• Cranial ultrasound (an ultrasound of the brain)
• Lumbar puncture and examination of the cerebrospinal fluid (rarely done)
• Skull x-rays

The goal of treatment is to reduce or prevent brain damage by improving the flow of CSF.

The blockage may be surgically removed, if possible. If the blockage cannot be removed, a shunt may be placed within the brain to allow CSF to flow around the blocked area. The shunt tubing travels to another part of the body, such as the abdomen, where the extra CSF can be absorbed.

Antibiotics are given if there are signs of infection. Severe infections may require the shunt to be removed.

Another option is endoscopic third ventriculostomy (ETV), which relieves pressure without replacing the shunt.

Removing or burning away (cauterizing) the parts of the brain that produce CSF may reduce CSF production.

Follow-up examinations generally continue throughout the child's life. These are done to check the child's developmental level and to treat any intellectual, neurological, or physical problems.

Visiting nurses, social services, support groups, and local agencies can provide emotional support and assist with the care of a child with hydrocephalus who has significant brain damage.

Untreated hydrocephalus has a 50-60% death rate, with the survivors having varying degrees of intellectual, physical, and neurological disabilities.

The outlook for treated hydrocephalus depends on the cause. Hydrocephalus that is caused by disorders not associated with infection has the best outlook. Persons with hydrocephalus caused by tumors usually do very poorly.

Most children with hydrocephalus that survive for 1 year will have a fairly normal life span. Approximately a third will have normal intellectual function, but neurological difficulties may persist.

Shunt placement may lead to blockage. Symptoms of such a blockage include headache and vomiting. Surgeons may be able to help the shunt open without having to replace it.

There may be other problems with the shunt, such as kinking, tube separation, or infection in the area of the shunt.

Other complications may include:

• Complications of surgery
• Infections such as meningitis or encephalitis
• Intellectual impairment
• Nerve damage (decrease in movement, sensation, function)
• Physical disabilities

Seek immediate medical care if your child has any symptoms of this disorder. Go to the emergency room or call 911 if emergency symptoms occur, which include:

• Breathing problems
• Extreme drowsiness or sleepiness
• Feeding difficulties
• Fever
• High-pitched cry
• No pulse (heart beat)
• Seizures
• Severe headache
• Stiff neck
• Vomiting

You should also call your health care provider if the child has been diagnosed with hydrocephalus and the condition gets worse and you are unable to care for him or her at home.

Protect the head of an infant or child from injury. Prompt treatment of infections and other disorders associated with hydrocephalus may reduce the risk of developing the disorder.

Kinsman SL, Johnston MV. Congenital anomalies of the central nervous system. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 592.

Golden JA, Bönnemann CG. Developmental structural disorders. In: Goetz, CG, eds. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 28.