What is hydrocephalus?

Hydrocephalus is a condition in which there is excessive fluid in and around the brain. It occurs from a lack of absorption, blockage of flow, or overproduction of the cerebral spinal fluid (CSF) that's made inside the ventricles. The ventricles are fluid-filled areas of the brain. The CSF disperses from the ventricles around the brain and spinal cord. Too much CSF may result in a buildup of fluid that can cause the pressure inside of the head to increase. In a child, this causes the bones of the skull to expand and separate to a larger-than-normal appearance.

What causes hydrocephalus?


Illustration of hydrocephalus
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Hydrocephalus occurs in approximately one out of 500 births. The following are the primary reasons why hydrocephalus occurs:

  • Blockage of the CSF flow inside of the head

  • Problems absorbing CSF

  • Overproduction of CSF (rare)

Hydrocephalus can occur either as a condition present at birth (congenital), or it can be acquired later in life. In some babies the condition is genetic, such as in babies with congenital aqueductal stenosis. Other conditions, such as neural tube defects (like spina bifida), are also associated with hydrocephalus. Other causes include premature birth, infections, tumors, or bleeding inside the brain. 

Causes of acquired hydrocephalus may include:

  • Tumor

  • Infection

  • Prematurity

  • Bleeding inside the head

  • Birth injury

  • Abnormal blood vessel formation inside of the head

  • Trauma

What are the symptoms of hydrocephalus?

The following are the most common symptoms of hydrocephalus in babies. However, each baby may experience symptoms differently. Symptoms may include:

  • A full or bulging fontanel (soft spot located on the top of the head)

  • Increasing head circumference (size)

  • Seizures

  • Bulging eyes and an inability of the baby to look upward with the head facing forward

  • Prominent scalp veins

  • Increased irritability

  • High-pitched cry

  • Poor feeding

  • Projectile vomiting

  • Sleepiness or less alert than usual

  • Developmental delays

The symptoms of hydrocephalus may resemble other conditions or medical problems. Always consult your baby's doctor for a diagnosis.

How is hydrocephalus diagnosed?

Hydrocephalus may be diagnosed before birth by prenatal ultrasound, a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. In many cases, hydrocephalus doesn't develop until the third trimester of the pregnancy and, therefore, may not be seen on ultrasounds performed earlier in pregnancy.

The diagnosis of congenital hydrocephalus may be made at birth and after diagnostic testing. During the examination, the doctor obtains a complete prenatal and birth history of the baby. He or she may also ask if there's a family history of hydrocephalus or other medical problems. The doctor will also ask about developmental milestones in older babies since hydrocephalus can be associated with developmental delay. Developmental delays may require further medical follow-up for underlying problems.

The baby's head may appear larger than normal. A measurement of the circumference of the baby's head is taken and compared to a graph that can identify normal and abnormal ranges for a baby's age.

Diagnostic tests that may be performed to confirm the diagnosis of hydrocephalus include:

  • Ultrasound. This diagnostic procedure uses sound waves to create an image of an internal portion of the body and can be used to determine the size of the ventricles in the womb and in neonates.

  • Magnetic resonance imaging (MRI). This diagnostic procedure uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within the body.

  • Computed tomography (CT) scan. This diagnostic imaging procedure uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.

What is the treatment for hydrocephalus?

Specific treatment for hydrocephalus will be determined by your baby's doctor based on:

  • Your baby's gestational age, overall health, and medical history

  • The extent of the condition

  • The type or cause of condition

  • Your baby's tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the condition

  • Your opinion or preference

The goal of treatment is to reduce the pressure in the baby's head and to properly drain the cerebral spinal fluid (CSF). Occasionally, medications or procedures to draw off the extra CSF may be used.

Surgery may be needed for some cases of hydrocephalus. Surgery usually involves placing a mechanical shunting device into the baby's head to help drain the extra CSF from the brain and redirect the extra fluid to another part of the body to be absorbed. A common type of shunt is the ventriculoperitoneal shunt. This directs the fluid into the abdominal cavity.


Illustration demonstrating ventriculoperitoneal shunt placement
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The shunt consists of three parts:

  1. A tube that's placed inside the ventricular space

  2. A reservoir and valve to control the flow of CSF

  3. Tubing that's directed under the skin to the abdomen, or less commonly to the heart or lung area

The shunt redirects the CSF out of the head through the tubing to a location elsewhere in the body where it can absorbed. The shunt usually runs behind the ear and the tubing is tunneled under the skin to the area of the abdomen, heart, or lung. Your baby's doctor will determine the drainage location based on your baby's condition, age, and other factors. The abdomen is generally the first choice.

Potential complications from the shunts or surgery can include:

  • Infection

  • Shunt malfunction that results in underdrainage or overdrainage of the CSF

  • Bleeding

These symptoms require prompt medical evaluation. Following surgery, you'll receive instructions on how to care for your baby at home and information about signs or symptoms requiring immediate medical attention.

Life-long considerations

Hydrocephalus can affect the brain and a baby's development. The extent of the problem is dependent on the severity of the hydrocephalus, and the presence of brain or other organ system problems.

The key to treating hydrocephalus is early detection, proper treatment, and prevention of infection. A baby with hydrocephalus requires frequent medical evaluations to ensure proper shunt function. The medical team works closely with the family to provide education and guidance as the baby grows and develops.

Genetic counseling may be recommended by the baby's doctor to discuss the risk for recurrence in future pregnancies, as well as prenatal testing for hydrocephalus.