Definition & Overview

The cerebrospinal fluid (CSF) is a clear fluid that surrounds the brain and the spinal cord. It functions as a cushion or shock absorber and is responsible for delivering nutrients to the brain, removing waste, and compensating for changes in intracranial blood volume.

Hydrocephalus occurs when too much cerebrospinal fluid builds up in the brain, causing harmful pressure on the brain’s tissues. If left untreated, it can cause permanent damage to the brain and affect the patient’s physical and mental development. On the other hand, if diagnosed and treated promptly, patients can lead a normal life with very few limitations.

Hydrocephalus can be either congenital or acquired. Congenital means that patients are born with the condition. Records show that approximately two in every 1,000 babies are born with hydrocephalus. The condition can also develop at any age after birth (acquired). Although it more commonly affects adults over the age of 60, it can also develop in younger adults.

Hydrocephalus is classified into specific forms, namely:

  • Communicating hydrocephalus - In this type of hydrocephalus, the flow of CSF is blocked after it exits the ventricles.

  • Obstructive hydrocephalus - Occurs when the flow of CSF is blocked along the passageways that connect the ventricles.

  • Hydrocephalus ex-vacuo - This is associated with strokes and some types of traumatic brain injuries.

  • Normal pressure hydrocephalus (NPH) - This is associated with subarachnoid haemorrhage, infection, tumour, and previous brain surgery.

Causes of Condition

Hydrocephalus can develop due to medical conditions that disrupt the normal absorption of cerebrospinal fluid in the brain. Since the brain is continuously producing and absorbing the fluid, any changes or disruption in this process may lead to CSF buildup. Some examples of problems or disruptions to this process include:

  • A blockage that prevents the fluid from flowing normally

  • Problems with the blood vessels in the brain that prevent them from absorbing the fluid properly

  • Overproduction of CSF

The following are the most common causes of congenital hydrocephalus:

  • Inherited genetic abnormalities - An example is the same defect that causes aqueductal stenosis in which a small passage between the third and fourth ventricles in the brain is narrowed.

  • Developmental disorders - Around 80 to 90 percent of babies born with certain developmental disorders, including spina bifida, meningocele, or myelomeningocele also develop hydrocephalus.

  • Premature birth or related complications - An example of these complications is intraventricular haemorrhage during a premature birth.

  • Infections during pregnancy

On the other hand, the following are risk factors associated with acquired hydrocephalus:

  • Traumatic head injury

  • Certain diseases, including meningitis

  • Tumour, especially those in the central nervous system

  • Previous brain surgery

  • Bleeding blood vessel in the brain

Key Symptoms

Aside from having an abnormally large head, patients suffering from hydrocephalus may also experience the following symptoms:

  • Frequent headaches

  • Nausea

  • Vomiting

  • Balance problems

  • Bladder control issues

  • Cognitive and memory problems

  • Blurred vision

In infants who do not have an abnormally large head, the condition may manifest through other symptoms, such as:

  • A bulging fontanel (or soft spot)

  • Excessive sleepiness and/or fussiness

  • Eyes fixed in a downward direction

  • Poor appetite

  • Poor muscle tone and lack of muscle strength

  • Rapidly increasing head circumference

  • Seizures

  • Vomiting

The symptoms may progress and become more pronounced as the child grows, resulting in:

  • Personality changes

  • Abnormal changes in the facial structure

  • Crossed eyes

  • Muscle spasms

  • Growth delays

  • Coordination problems

  • Bladder control problems

  • Difficulty staying awake

In older adults, the condition may also cause:

  • Walking difficulties

  • Gait instability

  • Urinary incontinence

  • Poor memory

  • Difficulty concentrating

  • Dementia

Other serious and life-threatening complications of the disease include:

  • Coma

  • Uncal or tonsillar herniation

  • Brain stem compression

About a quarter of hydrocephalic patients also develop epilepsy.

The range and severity of symptoms depend on the patient’s age, the cause of the condition, and the extent of brain tissue damage.

Who to See and Types of Treatments Available

Hydrocephalus is treated by neurosurgeons and neurologists, doctors who specialise in the treatment of disorders that affect the brain and spinal cord. In the course of their long-term medical care, patients may also be treated by occupational and developmental therapists as well as mental health providers. With the help of a complete medical care team, patients with the condition can live long and normal lives while managing the effects of the disease.

If a patient is not born with the condition, initial symptoms and suspicions should be brought to the attention of a family doctor, paediatrician, or general practitioner. These doctors can diagnose the condition by checking for signs and symptoms and performing some tests and scans, such as an ultrasound scan of the brain, magnetic resonance imaging (MRI), and computed tomography (CT) scan. Once diagnosed, the patient will be referred to a neurologist.

Treatment of hydrocephalus focuses on allowing the cerebrospinal fluid to flow normally to drain fluid buildup in the brain. This can be achieved with:

  • Shunt insertion - A shunt (a flexible plastic tube) that serves as an artificial drainage system for the cerebrospinal fluid is surgically inserted into the brain. This is a permanent treatment that requires long-term monitoring.

  • Ventriculostomy - A hole is made at the bottom of a ventricle in the brain to let the fluid flow through. It is important to note that hydrocephalus treatments cannot reverse any brain damage that has already occurred prior to the procedure. Thus, the prognosis for patients with the condition depends on how early the problem was detected and whether it was treated before any brain damage has already occurred.


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  • Al-Dosari MS, Al-Owain M, Tulbah M, Kurdi W, Adly N, et al. “Hydrocephalus.” Journal of Medical Genetics. Jan 2013; 50(1): 54-58.

  • Wilkinson D. “Ethical dilemmas in postnatal treatment of severe congenital hydrocephalus.” Camb Q Healthc Ethics. 2016 Jan; 25(1): 84-92.

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