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("Water on the Brain")

Pronounced: Hi-dro-sef-uh-liss

En Español (Spanish Version)


Hydrocephalus is a condition in which too much fluid builds up in the brain. The fluid collects in cavities called ventricles. The fluid is cerebrospinal fluid (CSF), a clear liquid that normally surrounds both the spinal cord and the brain.


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Hydrocephalus occurs when:

  • An excess of CSF is produced (rare)
  • A blockage that doesn't allow CSF to drain properly (more commonly)

Hydrocephalus can be:

  • Congenital—You are born with the condition.
  • Acquired—You suffer an injury or an illness that causes the condition to develop.


Causes include:

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Risk factors for hydrocephalus include:

  • Neural tube defects
  • Mother has infection during pregnancy
  • Brain infections
  • Malformations of the brain
  • Brain injuries


Symptoms of hydrocephalus depend on the area of the brain affected and the severity of the hydrocephalus. Symptoms may start out mild and become more severe as more CSF accumulates. The CSF puts pressure on structures within the brain, causing symptoms.

Symptoms may include:

  • Headache
  • Vomiting
  • Problems with balance
  • Difficulty walking
  • Poor coordination
  • Incontinence
  • Personality changes
  • Confusion
  • Memory problems
  • Dementia in the elderly
  • Coma and death
  • In babies:
    • Slow development
    • Loss of developmental milestones
    • Bulging fontanelle (soft spot on the head)
    • Large head circumference


The doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include:

  • CT scan—a type of x-ray that uses a computer to make pictures of the inside of the brain
  • MRI scan—a test that uses magnetic waves to make pictures of the inside of the brain
  • Ultrasound—a test that uses sound waves to examine the brain


Treatment may include:

  • Shunt placement (ventriculoperitoneal shunt)—In this surgical procedure, a shunt (a tube system that is implanted into the brain) allows excess CSF to drain into another area, usually the abdomen. Sometimes a temporary extraventricular drain (EVD) is placed.
  • Third ventriculostomy—This surgical procedure creates a hole in an area of the brain. It allows the CSF to flow out of the area where it is accumulating.
  • Lumbar puncture (spinal tap)—This involves the insertion of a needle between the lumbar vertebrae in the back to remove excess CSF.
  • Medications—In some cases, medications, such as acetazolamide (Diamox) and furosemide (Lasix), may decrease the production of CSF.


There are no known ways to prevent all cases of hydrocephalus. In general:

  • Get regular prenatal care
  • Protect yourself or your child from head injuries
  • Keep your child’s vaccines up to date

Preliminary research suggests that some cases due to brain bleeding in the newborn period may be preventable. Cytomegalovirus or toxoplasmosis acquired by a mother during pregnancy may be a cause of hydrocephalus in a newborn baby. Mothers may reduce their risk of being infected with toxoplasmosis with these steps:

  • Carefully cooking meat and vegetables
  • Correctly cleaning contaminated knives and cutting surfaces
  • Avoiding handling cat litter, or wearing gloves when cleaning the litter box.
Pet rodents (mice, rats, hamsters) often carry a virus called lymphocytic choriomeningitis virus (LCV). LCV infection acquired from pets during pregnancy can lead to hydrocephalus. This is preventable by avoiding rodent contact.

Infection with chickenpox or mumps during or immediately after pregnancy may also lead to hydrocephalus in the baby. Both of these infections can be prevented with vaccination. Other preventable infections may also cause hydrocephalus. People who have risk factors for hydrocephalus should be carefully monitored. Immediate treatment might prevent long-term complications.


American Association of Neurological Surgeons

American Neurological Association

Hydrocephalus Foundation, Inc.

National Institute for Neurological Disorders and Stroke


Health Canada

Spina Bifida and Hydrocephalus Association of Canada


Behrman RE, Kliegman R, Jenson HB. Nelson Textbook of Pediatrics . 16th ed. Philadelphia, PA: WB Saunders Company; 2000.

Goetz CG. Textbook of Clinical Neurology . Philadelphia, PA: WB Saunders Company; 1999.

Hydrocephalus. Mayoclinic.com website. Available at: http://www.mayoclinic.com/invoke.cfm?id=DS00393 . Accessed October 12, 2005.

Last reviewed November 2007 by Rimas Lukas, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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