Hydrocephalus Fast Facts

Hydrocephalus is a condition in which excess fluid builds up in cavities inside the brain. The accumulated fluid creates increased pressure on brain tissue inside the skull.

Hydrocephalus may be present at birth or triggered by some other condition or event later in life.

The condition can occur at any age, but it is most common in infants.

The severity of symptoms and complications varies depending on several factors, including the underlying cause and the effectiveness of treatment.

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Hydrocephalus may be present at birth or triggered by some other condition or event later in life.

What is Hydrocephalus?

Hydrocephalus is a condition that occurs when excess cerebrospinal fluid (CSF) accumulates in the fluid-filled spaces of the brain, the ventricles, causing them to become enlarged.  Normally, CSF flows through and out of the ventricles and protects the brain and the spinal column. CSF is regularly re-absorbed into the bloodstream, and the body produces new CSF to replace it. Hydrocephalus results when the flow of CSF is obstructed, too much CSF is produced, or not enough CSF is re-absorbed.

When too much CSF accumulates in the ventricles, pressure on brain tissue and the inside of the skull increases. This pressure can damage brain tissue and cause neurological symptoms. It can also cause malformation of the skull.

Symptoms of Hydrocephalus

Hydrocephalus symptoms vary from case to case and also typically vary depending on the age of onset. Common symptoms include:

In infants:

  • Enlarged head or a rapid increase in head size
  • A bulge in the soft spot (fontanel) on top of the baby’s head
  • Feeding difficulties
  • Irritability
  • Vomiting
  • Drowsiness
  • Eyes cast downward
  • Seizures

In toddlers and older children:

  • Headache
  • Vision disturbances
  • Vomiting
  • Problems with balance or coordination
  • Irritability
  • Sleepiness
  • Problems with bladder control
  • Developmental delays or loss of skills already acquired
  • Memory loss
  • Personality changes

In adults:

  • Problems with balance or coordination
  • Difficulty walking
  • Bladder control problems
  • Cognitive impairment

What Causes Hydrocephalus?

Hydrocephalus has many different causes. The condition may be congenital, meaning that it is present at birth, or it may be acquired, meaning that it occurs sometime after birth and is the result of some other triggering event. Common causes of hydrocephalus include:


  • Genetic conditions such as aqueductal stenosis
  • Defects in central nervous system development, such as spina bifida, that occur during pregnancy
  • Bleeding in the ventricles, which may be a complication of premature birth


  • Tumors in the brain or spinal cord
  • Central nervous system infection such as meningitis
  • Stroke
  • Head injury

Is Hydrocephalus Hereditary?

In many cases, hydrocephalus is caused by a disorder or event that is not inherited. However, some inherited genetic conditions are commonly associated with hydrocephalus, and these conditions run in families. An example is L1 syndrome, a genetic disorder that can cause aqueductal stenosis. This condition obstructs the normal flow of CSF and is the most common cause of congenital hydrocephalus.

How Is Hydrocephalus Detected?

The early symptoms of hydrocephalus may be similar to those of other disorders, making early diagnosis difficult. However, early treatment is often vital in preventing long-term and potentially life-threatening complications. In some cases, hydrocephalus may be diagnosed before birth during an ultrasound imaging scan.

Early warning signs of hydrocephalus in infants include:

  • Feeding difficulties
  • Irritability or excessive crying
  • Vomiting
  • Seizures

How Is Hydrocephalus Diagnosed?

A doctor may suspect hydrocephalus if a child or adult presents symptoms consistent with the disorder, and other potential causes of the symptoms can be ruled out. The diagnostic process may include:

  • Assessment of the child’s medical history
  • Physical and neurological exams
  • Imaging scans such as ultrasound, magnetic resonance imaging (MRI), or computerized tomography (CT) to look for CSF accumulation in the ventricles
  • Examination of the CSF via a lumbar puncture (spinal tap)
  • Intracranial pressure monitoring (ICP)
  • Examination of the optic nerve at the back of the eye, which may show swelling if hydrocephalus is present


How Is Hydrocephalus Treated?

Prompt treatment to relieve the pressure caused by hydrocephalus is often successful at preventing permanent brain damage and long-term complications. Treatment options are surgical and include:

  • Shunts. A shunt is a plastic tube that is inserted into the brain. The tube allows CSF to drain from the ventricles into another part of the body, usually the abdomen or chest, where it can be safely reabsorbed. Shunts typically have to be replaced multiple times during the patient’s lifetime.
  • Endoscopic third ventriculostomy (ETV). This procedure creates a small hole in one of the ventricles that allows excess CSF to drain away.
  • Choroid plexus cauterization. This procedure intentionally damages the tissue inside the ventricles that produces CSF so that less fluid will be created.

When hydrocephalus causes long-term complications, other therapies may be required, including:

  • Occupational therapy
  • Special education
  • Psychotherapy

How Does Hydrocephalus Progress?

When left untreated, hydrocephalus may cause complications that progressively worsen over time. About half of people with untreated hydrocephalus will die. Those who survive are likely to suffer from intellectual impairments, physical disabilities, and other serious complications. However, children whose hydrocephalus is treated early are likely to have an average lifespan, and may experience no significant complications.

How Is Hydrocephalus Prevented?

There is no known way to prevent hydrocephalus, but avoiding risk factors may decrease the likelihood of both congenital and acquired forms of the condition. Risk-reducing steps to take include:

  • Get good prenatal care during pregnancy to prevent premature birth and other complications.
  • Get vaccinated according to your doctor’s recommendations.
  • Make sure your child follows safety rules to prevent head injuries.
  • Seek the advice of a genetic counselor if you have a family history of conditions associated with hydrocephalus.

Hydrocephalus Caregiver Tips

  • Stay on top of your child’s condition and medical care. Be alert for signs of complications, including developmental delays, speech problems, or motor difficulties. Keep a log of your observations so you can easily bring your concerns to your doctor’s attention.
  • Ensure you know the warning signs of potentially serious conditions such as recurrent accumulation of CSF or shunt malfunctions. Contact your doctor promptly when you see any of these signs.  
  • Find a community of people who can help. The Hydrocephalus Association maintains resources, including links to support groups, for families living with hydrocephalus.

Many people with hydrocephalus also suffer from other brain and mental health-related issues, a situation called co-morbidity. Here are a few of the disorders commonly associated with hydrocephalus:

Hydrocephalus Brain Science

Hydrocephalus is a common neurological condition, but its precise causes at a cellular level are still not entirely understood. Research is ongoing into the causes and mechanism of the condition, as well as potential treatments and new diagnostic tools. Current areas of research include:

  • Identification of gene mutations that may be associated with congenital hydrocephalus
  • The role of amniotic fluid and stem cells in early brain development
  • Identification of new risk factors for developing the condition
  • New ways to diagnose shunt malfunctions

Hydrocephalus Research

Title: Hyperfine Portable MRI in Hydrocephalus and Other Conditions Prompting Outpatient Brain Imaging

Stage: Recruiting

Principal investigator: Joel Stein

University of Pennsylvania

Philadelphia, PA

Hydrocephalus is a medical condition in which an abnormal buildup of cerebrospinal fluid (CSF) causes the fluid-filled spaces of the brain, the ventricles, to become enlarged. Enlarged ventricles and increased intracranial pressure can cause headaches, dizziness, blurred vision, cognitive impairment, gait disturbances, and in severe cases, even brain herniation or death. A tube or shunt can be inserted into the ventricles to drain the CSF either outside the body temporarily or into the abdominal cavity for long-term treatment. Sometimes such shunts need to be adjusted or replaced if fluid re-accumulates. Medical imaging scans, either computer tomography (CT) or magnetic resonance imaging (MRI), are used to diagnose hydrocephalus in adults and children.

The purpose of this pilot study is to assess the performance of a newly developed, portable, low-cost MRI machine (Hyperfine MRI) in diagnosing and following patients with hydrocephalus in comparison to routine clinical CT or MRI. Outpatients with known or suspected hydrocephalus with or without ventricular shunts will be recruited to undergo Hyperfine MRI in conjunction with their routine clinical imaging. Researchers will evaluate both the feasibility and acceptability of using the Hyperfine unit in the outpatient setting as well as the performance of Hyperfine MRI images in identifying hydrocephalus and other key brain imaging features relative to routine CT and MRI.

Outpatients with other known or suspected neurological disorders or conditions prompting routine clinical brain imaging with MRI or CT will also be enrolled, and the diagnostic performance of low field scans compared to that of the same day standard of care clinical imaging.


Title: NIRS Monitoring in Premature Infants

Stage: Recruiting

Principal investigator: Pei-Yi Lin, PhD

Boston Children’s Hospital

Boston, MA

This study uses frequency domain near-infrared spectroscopy coupled with diffuse correlation spectroscopy (FDNIRS-DCS) technology for monitoring cerebral blood flow (CBF) and cerebral oxygen metabolism (CMRO2) at the bedside for newborns with germinal matrix-intraventricular hemorrhage (GM-IVH) and/or post-hemorrhagic hydrocephalus (PHH) in comparison to newborns with hydrocephalus of a different etiology (VC) and healthy controls (HC). We hypothesize that baseline cerebral metabolic dysfunction is a better biomarker for GM-IVH and PHH severity and response to PHH treatment.

This is a Boston Children’s Hospital (BCH)-institutional review board(IRB) approved, multi-site study that includes collaboration with Brigham and Women’s Hospital (BWH) and Beth Israel Deaconess Medical Center (BIDMC). Pei-Yi Lin receives funding from The National Institute of Health (NIH) to support the study and is the overall principal investigator (PI) overseeing the study.


Title: HCRN Endoscopic Versus Shunt Treatment of Hydrocephalus in Infants (ESTHI)

Stage: Recruiting

Principal investigator:  Curtis Rozzelle, MD

Children’s of Alabama

Birmingham, AL

Hydrocephalus is a potentially debilitating neurological condition that primarily affects babies under a year of age and has traditionally been treated by inserting a shunt between the brain and the abdomen. A newer endoscopic procedure offers hope of shunt-free treatment that may reduce complications over a child’s life, but it is unclear if the endoscopic procedure results in a similar intellectual outcome as a shunt. Therefore, the investigators propose a randomized trial to compare intellectual outcome and brain structural integrity between these two treatments to help families make the best treatment decision for their babies.

The ESTHI Trial is a multi-center randomized controlled trial (RCT) comparing endoscopic third ventriculostomy with choroid plexus cauterization (ETV+CPC) and shunt in infants with hydrocephalus. The study will leverage the infrastructure of the Hydrocephalus Clinical Research Network (HCRN), a committed group of 14 leading North American pediatric neurosurgical centers with a long track record of successful collaborative clinical research and RCTs in hydrocephalus. Optimal cognitive outcome is the primary concern of families and will, therefore, be the primary outcome. Assessment of dMRI, a validated, non-invasive method of measuring white matter microstructural integrity and structural connectivity in the developing brain, will provide further insight into the developmental consequences of these two treatments. The results of the RCT will help families determine the optimal treatment of hydrocephalus for their child.

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