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  • A condition that causes excess fluid to build up in and around the brain
  • Risk factors include age, infection during pregnancy, family history, or head injuries
  • Treatment consists of shunt placement or endoscopic third ventriculostomy
  • Involves neurosurgery


Our brains usually have a clear, colorless fluid to cushion the brain and spinal cord. However, sometimes that can accumulate around the brain and enlarge the spaces within the brain. This condition is called hydrocephalus, or  “water on the brain,” and can cause neurological problems.

Hydrocephalus affects children and adults and often requires prompt treatment, usually via neurosurgery, to help drain the fluid from the brain.

"Our combined pediatric and adult approach in a single hospital makes Yale Medicine a unique environment for the transitional care of young adults with hydrocephalus, providing continuity for individuals diagnosed as children and who require lifelong treatment," says Yale Medicine neurosurgeon Kristopher Kahle, MD.

What is hydrocephalus?

Normal pressure hydrocephalus is a brain disorder that primarily affects the elderly and occurs when excess cerebrospinal fluid, which is made in the brain, accumulates inside the brain instead of being reabsorbed into the bloodstream.

It's called “normal pressure” because despite the extra fluid in the brain, the pressure of the cerebrospinal fluid is measured is still within normal levels.

In children, hydrocephalus is more commonly “high pressure.” A child may develop hydrocephalus before birth (congenital hydrocephalus) or during childhood (acquired hydrocephalus).

What causes hydrocephalus in children and in adults?

The exact cause of normal pressure hydrocephalus isn't well understood. The brain produces cerebrospinal fluid at a constant rate that doesn't fluctuate—much like a water faucet that's been left running. When the brain's ability to reabsorb this fluid properly is disrupted for whatever reason, it accumulates, which then causes hydrocephalus.

In children, the inability to properly reabsorb cerebrospinal fluid can be due to a birth defect, abnormal development of the nervous system, or structural problems in the brain.

Hydrocephalus may also be a result of spina bifida (a birth defect in which a child’s spinal cord doesn’t develop properly), bleeding, infections, head trauma, tumors, or cysts.

Who is at risk for hydrocephalus?

Generally, the elderly are most at risk for normal pressure hydrocephalus. For reasons medical researchers are still working to understand, the body's ability to effectively reabsorb cerebrospinal fluid may become impaired as we age.

The risk of hydrocephalus in children is increased if a pregnant woman contracts an infection during pregnancy, which can result in inflammation of the child's brain tissue. Other risk factors are a family history of hydrocephalus and head injuries suffered during childbirth or in childhood.

What are the symptoms of hydrocephalus in children and in adults?

Hydrocephalus in infants is typically identified by a baby's rapidly growing head size. Abnormal head growth may be accompanied by vomiting, excessive sleepiness, irritability, poor appetite, or seizures.

In toddlers and older children, rapid enlargement of the head isn't typical, but the other symptoms mentioned previously may be present, along with headaches, double vision, or blurred vision.

In adults, normal pressure hydrocephalus is traditionally thought to present three symptoms: difficulty walking, cognitive problems such as trouble with decision-making or slowed thinking, and urinary incontinence.

Yale Medicine has been at the forefront of newer thinking that normal pressure hydrocephalus is a spectrum disorder and that patients with normal pressure hydrocephalus may experience varying degrees of each of those three key symptoms.

How is hydrocephalus diagnosed?

Normal pressure hydrocephalus is diagnosed via a computerized tomography (CT) scan or magnetic resonance imaging (MRI).

Adult patients also undergo a lumbar drain trial: A test in which cerebrospinal fluid is drained from the back. Patients are then assessed over three days by the neurosurgery team and physical therapists to see if they will benefit from having a shunt permanently implanted in the brain to drain excess fluid.

Yale Medicine is the only institution in Connecticut to routinely offer this lumbar drain trial diagnostic test, which is more effective and has fewer side effects than traditional techniques used at other medical centers.

Depending on the child's age, a diagnosis of pediatric hydrocephalus can be confirmed by ultrasound (for infants who are less than 1 year old) or through a magnetic resonance imaging (MRI) or computerized tomography (CT) scan.

What are the treatment options for hydrocephalus?

Treatment for normal pressure hydrocephalus consists of surgery to place a shunt in the brain that redirects excess cerebrospinal fluid into the abdomen, lungs, or heart.

Patients treated at Yale Medicine undergo an aggressive examination to determine whether they will or won't benefit from placement of a shunt.

Pediatric hydrocephalus is usually treated with surgery to implant a shunt that allows blocked fluid to drain safely into the child's abdomen.

Some forms of pediatric (and adult) hydrocephalus may be treated by endoscopic third ventriculostomy (ETV), a minimally invasive form of spinal fluid diversion that eliminates the need for shunt placement.

In the procedure, an endoscope—or tiny, fiber-optic camera—provides a clear picture of the ventricles within the brain, where the cerebrospinal fluid is produced. Surgeons are able to cut an opening in the ventricle, making it possible to bypass an obstruction and restore normal fluid flow.

Is it possible to fully recover from hydrocephalus?

When normal pressure hydrocephalus is treated with a shunt, it stops the condition from progressing and often alleviates symptoms, improving the patient's quality of life.

The outcome for most children with hydrocephalus is also very good, but some children have complications, such as shunt malfunctions and infections from surgery, developmental delays, learning disabilities, and visual problems.

Families need to be aware of the lifelong complexities of hydrocephalus to ensure their children receive comprehensive ongoing care and appropriate intervention services and therapies.

What makes Yale Medicine’s approach to hydrocephalus in children and adults unique?

Our specialists treat more cases of normal pressure hydrocephalus than any other medical practice or institution in Connecticut. Our pediatric neurosurgeons are pioneers in the use of endoscopes (tiny fiber-optic cameras) to surgically treat pediatric hydrocephalus. We offer endoscopic third ventriculostomy (ETV) combined with choroid plexus cauterization (CPC), a pioneering approach that enables many children to recover from hydrocephalus without a shunt.

"What we do here differently is two-fold—on the diagnostic side, if you go anywhere else in the country, they'll get an MRI or CT scan and say you have hydrocephalus because your cerebral ventricles are too big. What we get at is to look at the actual cause of the hydrocephalus," he said.