Hydrocephalus

Your brain and spinal cord are surrounded by a clear liquid called cerebrospinal fluid (CSF). This fluid circulates around your brain’s four cavities – or ventricles – to cushion and protect the brain, remove waste products and supply nutrients.

When the normal flow of CSF is blocked, it may lead to a condition called hydrocephalus or “water on the brain.” When hydrocephalus occurs, the buildup of excess CSF fluid on the brain causes your ventricles to enlarge and, in some cases, causes the pressure in your brain to increase. This may impact your brain function, leading to symptoms such as memory loss, changes in personality and trouble standing or walking.

Hydrocephalus can be present at birth, leading to the hallmark symptom of an enlarged or bulging head in newborns. Older children and adults can also develop a type of hydrocephalus from a traumatic brain injury or illness. With early intervention, surgical treatment and monitoring, it’s possible to manage this condition with little or no complications.

Types of hydrocephalus

There are four main types of hydrocephalus. They differ due to the root cause of the CSF disruption.

Normal pressure hydrocephalus is most common in older adults. Non-communicating and communicating hydrocephalus are most common in infants. Hydrocephalus ex-vacuo occurs after a traumatic brain injury or illness.

• Communicating hydrocephalus: CSF flows through your ventricles but is blocked after exiting. This type is caused by the thickening of membranes at the base of your brain (arachnoid).
• Non-communicating hydrocephalus: Flow of CSF is blocked due to the narrowing of passages connecting your ventricles (aqueductal stenosis). It’s also known as obstructive hydrocephalus.
• Hydrocephalus ex-vacuo: CSF builds up in your enlarged ventricles, left by shrinking brain tissue caused by a brain injury or illness. Head pressure usually remains normal.
• Normal pressure hydrocephalus: CSF doesn’t drain properly out of your ventricles, allowing the gradual buildup of CSF with little increase in pressure. This type is slow moving.

Hydrocephalus causes

Depending on the type, a combination of genetic and health factors may cause the condition. Hydrocephalus can be congenital (present at birth) or acquired (occurs after birth).

Congenital hydrocephalus is more common than acquired hydrocephalus. A newborn is born with hydrocephalus in 2 out of every 1,000 births in the United States.

Common causes of congenital hydrocephalus:

• Cerebral aqueduct stenosis, which narrows the third and fourth ventricles in the brain
• Spina bifida, which affects the brain and spine, causing a neural tube defect (encephalocele)
• Intraventricular hemorrhage (IVH) that causes bleeding in the ventricles, which can result from premature birth complications
• Infections during pregnancy that cause inflammation in fetal brain tissue, such as rubella or syphilis

Common causes of acquired hydrocephalus:

• Stoke or injury, leading to bleeding in the brain
• Bacterial meningitis or mumps, which affect nervous system function
• Brain hemorrhage
• Brain tumors
• Spinal cord tumors
• Traumatic brain injuries (TBI)

If left untreated, hydrocephalus can be fatal or lead to life-long complications.

Hydrocephalus symptoms

Symptoms of hydrocephalus vary with age. Physical symptoms, such as an enlarged head, are common in newborn and younger children – often referred to as the “fluid on the brain” symptom. Adults commonly experience more behavioral and cognitive changes.

Newborn hydrocephalus symptoms:

• Bulging soft spot on the top of the head (fontanel)
• Unusually large head
• Rapid increase in the size of head
• Downward gaze of the eyes (sunsetting eyes)
• Lethargy
• Irritability
• Vomiting
• Muscle tone and strength problems
• Poor appetite

Hydrocephalus symptoms in children:

• Developmental delays
• Unusually large head
• Headaches
• Irritability
• Nausea and vomiting
• Vision problems
• Unusual eye movements
• Balance and coordination problems
• Poor appetite
• Loss of bladder control

Adult hydrocephalus symptoms:

• Headaches
• Balance and coordination problems
• Nausea and vomiting
• Memory and concentration issues
• Vision problems
• Tiredness
• Loss of bladder control and frequent urination

Older adult hydrocephalus symptoms:

• Mild dementia
• Loss of bladder control and frequent urination
• Memory loss
• Trouble walking
• Balance and coordination problems

Diagnosing hydrocephalus 

A neurological exam is the first step in diagnosing hydrocephalus. To find the source of hydrocephalus, your doctor will ask about your symptoms and may recommend a variety of tests, including:

• An MRI
• A CT scan
• Lumbar puncture (also known as a spinal tap)
• Intracranial pressure monitoring
• A variety of neurological and psychological tests to rule out other conditions

Hydrocephalus treatment

Surgery will be needed to treat and manage hydrocephalus. In addition to the surgical treatments, you may receive neurological physical therapy to help regain any loss of function.

The most common type of treatment for newborns, children and adults includes a hydrocephalus shunt. The shunt system is placed in the brain or spinal cord. Using a small, flexible tube, the system drains the excess CSF fluid to another part of the body like the stomach, where it can be more easily absorbed.

The shunt will need to be monitored and adjusted over time with regular medical visits to avoid possible complications such as an infection or break in the system. Most shunts can be managed externally using a magnet.

Another form of brain surgery used to treat hydrocephalus is endoscopic third ventriculostomy (ETV). This surgery creates a pathway to regain the normal flow of CSF by creating a small hole in the floor of the third ventricle. It’s only recommended as an alternative to a shunt system for those who have a blockage and are over the age of 2.