Hydrocephalus

Hydrocephalus is a buildup of cerebrospinal fluid (CSF) in the spaces deep inside your brain (ventricles). As a result of the excess fluid, the ventricles widen and put pressure on the brain tissue. In hydrocephalus, the cycle that allows CSF fluid to flow freely is out of balance and fluid builds up in the ventricles. This buildup can be a result of:

• Blocked flow of CSF in the brain
• Increased production of CSF
• Reduced absorption of CSF

Hydrocephalus is a serious condition that affects children and adults and can cause severe disability or death. Early diagnosis and treatment can greatly improve your symptoms and prognosis.

Where is cerebrospinal fluid produced?

CSF is a liquid that surrounds your brain and spinal cord. The function of CSF is to:

• Carry away wastes produced by brain cells
• Deliver nutrients to your brain
• Protect your brain and spinal cord against trauma and injury

There are four ventricles, or hollow cavities, inside the brain that continuously make and reabsorb CSF. The cavities connect, allowing CSF to flow freely between them. CSF travels out of the ventricles into the space around the brain and spinal cord (subarachnoid space). The brain absorbs the CSF and transports it to the veins for disposal.

The total volume of CSF turns over about three times every day. This rapid production means that a buildup of CSF in your brain can occur rapidly.

Types of hydrocephalus

Hydrocephalus varies based on where the blockage occurs and whether it causes increased pressure in the skull:

• Communicating hydrocephalus: The buildup of CSF occurs due to a blockage in flow outside the ventricles or due to reduced reabsorption. Increased CSF creates elevated pressure inside the ventricles.
• Noncommunicating hydrocephalus: A passage between the ventricles becomes blocked, leading to a buildup of CSF and increased pressure.
• Normal pressure hydrocephalus: There is a slow increase in fluid, which allows the tissues around the ventricles to expand. But pressure in the brain does not increase.

How common is hydrocephalus?

Hydrocephalus is most common in infants and older adults. Estimates of hydrocephalus range from 88 per 100,000 children to 400 per 100,000 adults over age 80.

Infants may have a congenital defect at birth that causes hydrocephalus. Other causes of hydrocephalus in infants include:

• Maternal infection during pregnancy
• Premature birth

Hydrocephalus can occur at any age due to other conditions, such as:

• Accident or trauma to the head
• Infections of the brain and spinal cord, such as meningitis
• Idiopathic intracranial hypertension
• Tumors of the brain or spinal cord
• Stroke

In normal pressure hydrocephalus, the cause is often unknown (idiopathic).

Without surgical treatment, hydrocephalus can cause permanent brain damage and death. The two main types of surgery include: 

• Ventriculoperitoneal (VP) shunt: A VP shunt is a tube that diverts CSF from the brain to the abdomen, where it is absorbed. A surgeon inserts the tube into a ventricle and threads the tube under the skin to the abdominal area. A valve placed on the tube helps manage the flow of fluid. A VP shunt is the most common treatment for hydrocephalus. 
• Endoscopic third ventriculostomy (ETV): This is a minimally invasive procedure that eliminates the need for a shunt. The surgeon uses a thin tube (endoscope) and tiny instruments to create a small hole at the bottom of one of the ventricles. The opening allows fluid to drain and relieves pressure. ETV is an option for noncommunicating hydrocephalus. 

Shunts are usually very effective but require ongoing monitoring to make sure they are working properly. Complications that can arise with a shunt include infection and a return of symptoms. 

At Penn, our interdisciplinary teams provide coordinated, ongoing care to protect your or your child’s health. 

Read more about hydrocephalus care for children at the Children’s Hospital of Philadelphia Neuroscience Center.