What Is the Main Cause of Hydrocephalus?

Medically Reviewed on 12/16/2022
Main Cause of Hydrocephalus
Since hydrocephalus has no cure, brain surgery is currently the only viable therapy.

Hydrocephalus is caused by the accumulation of cerebrospinal fluid within the ventricles of the brain and builds up pressure in the skull, resulting in swelling of the brain.

Hydrocephalus is a rare, complex, and chronic illness that can arise for a variety of reasons or even be a result of another disorder. It can be congenital (a person is born with it), acquired, or developed because of aging.

Other causes of hydrocephalus include:

What causes hydrocephalus?

The choroid plexus, a tissue within the ventricles, continuously produces cerebrospinal fluid (CSF), which flows through the ventricles, down the spinal cord, and across the brain's surface.

On reaching the brain's surface, CSF is reabsorbed into the bloodstream by specific structures called arachnoid villi. CSF production, circulation, and resorption are continuous and consistent cycles.

When there is an obstruction in the flow, a problem with reabsorption, or an overproduction of CSF, fluid accumulates and hydrocephalus develops. It is still unclear what causes CSF buildup in the brain, resulting in severe disabilities in patients with hydrocephalus.

It affects 1 or 2 per 1,000 live births in the United States. However, with advancements in medicine, the death rates have decreased from 54 to 5 percent, and intellectual disabilities have decreased from 62 to 30 percent in the past 25 years. 

Children may be born with congenital hydrocephalus or may develop it later in life. Because it is more common in some families, it is believed that hydrocephalus may have a hereditary component. Hydrocephalus is typically caused by CSF obstruction or a lack of reabsorption.

The following are the most common causes of hydrocephalus:

  • Premature birth complications
  • Pregnancy-related infection
  • Infection of the brain
  • Tumors of the brain
  • Brain bleeding caused by an accident or stroke
  • Spina bifida (incomplete spinal cord development)
  • Stenosis of the aqueduct (blocked flow of CSF between ventricles)

Sometimes, the diagnosis of hydrocephalus is easier than that of other conditions. Irrespective of the cause, hydrocephalus can cause brain damage and prevent newborns from reaching crucial developmental milestones. Untreated or worsening hydrocephalus can lead to intellectual, developmental, and physical impairments. Hydrocephalus is potentially fatal, but with proper treatment, the severity can be reduced and severe complications may be avoided.

What are the types of hydrocephalus?

Hydrocephalous is classified into various types depending on the time of onset and cause, such as:

  • Congenital hydrocephalus
    • It occurs at birth and is caused by a complex combination of genetic and environmental factors during fetal development
    • Routine ultrasonography is now used to diagnose congenital hydrocephalus before delivery.
  • Acquired hydrocephalus
    • This form of hydrocephalus is acquired after birth or later in life due to a neurological disease or trauma.
    • It can affect people of all ages.
  • Communicating and noncommunicating hydrocephalus
    • Communicating hydrocephalus occurs when the flow of cerebrospinal fluid (CSF) is blocked after it leaves the ventricles. The CSF may still flow between the ventricles, which are still open. 
    • Noncommunicating hydrocephalus (also known as obstructive hydrocephalus) arises when the flow of CSF is blocked along one or more channels connecting the ventricles.
  • Compensated hydrocephalus
    • It is also known as arrested hydrocephalus. It is a type of hydrocephalus that is present at birth and may be treated in early infancy.
    • Most cases of compensated hydrocephalus remain asymptomatic for several years.
  • Normal pressure hydrocephalus
    • This usually occurs in older adults when the ventricles of the brain grow, but there is little or no rise in pressure within the ventricles. 
    • In some cases, the cause may be recognized, but it is mostly idiopathic (the reason remains unknown).

What are the symptoms of hydrocephalus?

Signs and symptoms of hydrocephalus differ depending on the age of onset.

  • Newborn children
    • Exceptionally large head 
    • The rapid increase in the size of the head 
    • A bulging or tight soft region on the top of the head
    • Lethargy
    • Irritability
    • Muscle tone and strength issues
    • Poor eating habits
    • Seizures 
    • Fixed gaze downward (sunsetting of the eyes)
  • Toddlers and older kids
    • Irritability
    • Headache
    • Sleepiness 
    • Nausea and vomiting
    • Unstable equilibrium
    • Coordination issues
    • Loss of appetite 
    • Bladder control issues
    • Abnormal eye movements
    • Vision issues
    • Changes in behavior and cognition
    • Worsening of academic performance
  • Adults
    • Headache
    • Coordination or balance problems
    • Sluggishness
    • Frequent urination
    • Loss of bladder control
    • Vision issues
    • Deterioration of memory, focus, and other cognitive abilities 
    • Reduced work performance
  • Older adults (aged more than 60 years)
    • Urge to urinate frequently 
    • Loss of bladder control
    • Inadequate coordination or balance
    • Difficulty walking
    • Memory loss
    • Deteriorating cognitive or reasoning skills

It is important to seek emergency medical attention for babies and toddlers who exhibit the following signs and symptoms:

  • Sucking or feeding difficulties
  • High-pitched crying
  • Recurrent vomiting 
  • Seizures

As the symptoms of hydrocephalus can be caused by more than one disorder, it is crucial to have a prompt diagnosis and suitable treatment.


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How is hydrocephalus diagnosed?

When a doctor suspects hydrocephalus, they conduct a complete clinical assessment, including a physical examination as well as the collection of the complete medical and family history of the patient.

To confirm the diagnosis and determine treatment options, doctors frequently recommend a comprehensive neurological examination, including one or more of the following tests:

The results of these tests may provide important information regarding the severity of the disease and its possible cause.

How is hydrocephalus treated?

Unfortunately, hydrocephalus has no cure. Brain surgery is presently the only viable therapy.

The treatment depends on the severity of the condition and other aspects, such as symptoms, age, and overall health of the child. These factors are considered to determine the appropriate treatment.

The main goal of the treatment is to relieve the pressure within the child’s head. This can be accomplished by removing the excess fluid through medications or surgical intervention.


Surgical intervention is the most common approach for treating hydrocephalus. A mechanical shunting device is normally implanted in the child’s head during surgery. Removal of excess fluid from the brain is achieved by directing the fluid to a different part of the body for absorption. The shunt is often located behind the ear. A tubing is inserted beneath the baby's skin and leads to the abdomen, heart, or lungs.

The drainage site is determined by the surgeon by taking into consideration of the child’s health, age, and other circumstances. The abdomen is usually the first choice; a ventriculoperitoneal shunt is used to transfer fluid into the abdomen.

Medically Reviewed on 12/16/2022
Image Source: iStock image

About Hydrocephalus: https://www.hydroassoc.org/about-hydrocephalus/

What is Hydrocephalus? https://www.cincinnatichildrens.org/health/h/hydrocephalus

Hydrocephalus Overview: https://www.wellstar.org/medical-services/health-conditions-diseases/hydrocephalus