Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 29, 2016

Hydrocephalus sometimes referred to as water on the brain is characterized by an abnormal buildup of fluid in the cavities or ventricles of the brain. This causes the brain to swell and the pressure inside of the skull to increase. This can cause serious brain damage resulting in various intellectual, physical, and developmental impairments


Definition & Facts

Hydrocephalus affects an estimated one million people in the United States. The condition is most common among young children and younger adults. Hydrocephalus can be acquired or congenital, meaning the condition is present at birth. Under normal circumstances, cerebrospinal fluid is produced and circulated through the ventricles of the brain and eventually reabsorbed into the bloodstream. This fluid provides nutrients necessary for normal brain function, carries away waste products from surrounding tissue, and serves as a protective cushion against injury. Hydrocephalus is the result of an imbalance between the amount of cerebrospinal fluid that is produced and how quickly it is reabsorbed, which can cause the fluid to build up in the ventricles of the brain. 

Symptoms & Complaints

The symptoms of hydrocephalus can vary depending on the age of the individual at the time of onset. In infants, the most obvious signs are a rapid increase in head size and a bulging soft spot on the surface of the skull. This may be accompanied by fussiness, poor eating, frequent vomiting, poor muscle strength and tone, excessive sleepiness, and eyes that are fixed downward.

Slightly older children may have the same symptoms as well as headaches, a high-pitched cry, personality changes, difficulty concentrating, delayed growth, muscle spasms, seizures, and loss of coordination and loss of bladder control. Adults may experience chronic headaches, a decline in memory and reasoning skills, a loss of coordination and difficulties with balance, loss of bladder control, and slowed movements. 


The accumulation of cerebrospinal fluid in the brain can be caused by a variety of factors including:

  • A partial obstruction preventing the cerebrospinal fluid from flowing from one ventricle to another or from the ventricles to other areas around the brain.
  • Brain inflammation due to injury or disease that affects the ability of the blood vessels to reabsorb the cerebrospinal fluid.
  • The brain may produce cerebrospinal fluid more quickly than it can be reabsorbed. 

Congenital hydrocephalus can be the result of any of the following:

Acquired hydrocephalus can occur at any age due to:

Diagnosis & Tests

During a physical examination, a doctor will look for physical signs that could indicate hydrocephalus. In infants and very young children, the doctor will look for a bulging fontanelle, a larger than normal head circumference, and sunken eyes. Depending on the age of the patient, the doctor will perform a neurological examination to assess reflexes, muscle strength and tone, coordination and balance, and sensory function.

Brain imaging is useful in confirming the diagnosis and in determining the possible cause of the hydrocephalus. Ultrasounds are often used to identify enlarged brain ventricles and possible hydrocephalus in utero. Ultrasounds use high-frequency sound waves to create images of the structures of the brain. The test is simple, non-invasive, and low-risk, which is why it is often preferred for infants and young children.

MRIs and CT scans may also be used to look for signs of cerebrospinal fluid buildup and enlarged brain ventricles. While these tests are painless, they do require the patient to lie still for 20 minutes to an hour, which means children may require mild sedation

Treatment & Therapy

Treatment for hydrocephalus can prevent possibly fatal complications of the condition; however, it cannot reverse any existing brain damage. Many individuals with hydrocephalus require a multidisciplinary treatment team that includes occupational, physical, and developmental specialists to help overcome and manage their disability. 

The most common treatment is a surgical procedure to insert a device called a shunt into the brain. A shunt is a long tube with a valve. One end of the shunt is implanted in the brain, and the other end goes into the chest or abdominal cavity. The tube allows excess cerebrospinal fluid to drain from the brain to the abdominal cavity where it is reabsorbed.

The valve ensures that the fluid drains at the proper rate and in the right direction. A shunt must be monitored regularly to make sure it is functioning properly and is typically permanent. Like any other medical device, shunts can pose a risk for complications, including infection and over-draining or under-draining.

In rare cases, a procedure called a ventriculostomy may be used as an alternative to implanting a shunt. This involves using a small fiber optic camera to allow the doctor to visualize the ventricular surface of the brain. Once the scope is in place, the doctor uses a small tool to create a tiny hole in the bottom of the ventricle that allows the cerebrospinal fluid to drain freely so that it can be reabsorbed. 

Prevention & Prophylaxis

There is little that can be done to prevent hydrocephalus; however, certain steps can reduce the risk of serious complications. Regular prenatal care can reduce the likelihood of premature labor. It can also lead to an earlier diagnosis so that treatment can begin as soon as possible, which reduces the chance for long-term developmental problems.

Routine vaccinations can prevent illnesses and infections, such as meningitis, that are linked to an increased risk of hydrocephalus. Safety equipment, such as helmets, seat belts, and car seats, can lower the chances of head injuries that can cause hydrocephalus.