What is hydrocephalus?
Hydrocephalus is the abnormal buildup of fluid within your brain. Hydrocephalus comes from the Greek words “hydro,” which means water, and “cephalus,” which means head. Hydrocephalus was once known as “water on the brain.” The “water” is actually cerebrospinal fluid (CSF) — a clear, colorless fluid surrounding your brain and spinal cord.
Normally, CSF flows through areas in your brain called ventricles. CSF serves as a nutrient delivery and waste removal system for your brain. CSF bathes your brain and spinal cord, protecting and cushioning them from injury. CSF is then reabsorbed into your bloodstream.
Your body usually produces the CSF it needs each day and then reabsorbs the same amount. However, when the normal flow or absorption of CSF is blocked, it can result in a buildup of CSF. As the CSF builds up, it causes the ventricles to enlarge. This causes pressure inside of your head to increase. The pressure from too much CSF can keep your brain from functioning properly.
Who can get hydrocephalus?
One to 2 of every 1,000 babies in the United States are born with hydrocephalus. But hydrocephalus also affects older children and adults of all ages.
What are the different types of hydrocephalus?
The four main types of hydrocephalus are communicating hydrocephalus, non-communicating hydrocephalus, normal pressure hydrocephalus and hydrocephalus ex-vacuo.
- Communicating hydrocephalus occurs when the flow of CSF is blocked after it leaves your ventricles. This type of hydrocephalus may result from a thickening of membranes at the base of your brain called arachnoid. This blockage prevents the free flow of CSF. This type of hydrocephalus is called communicating because the CSF can still flow between your ventricles, which remain open.
- Non-communicating hydrocephalus is also known as obstructive hydrocephalus. Non-communicating hydrocephalus occurs when the flow of CSF is blocked along one or more of the narrow passages connecting your ventricles.
- Normal pressure hydrocephalus (NPH) happens when CSF buildup causes your ventricles to enlarge, but there’s little to no increase in pressure. The difference between NPH and other types of hydrocephalus is that even though there’s a larger than normal amount of CSF, the pressure inside of your ventricles remains the same. The buildup of CSF in your ventricles happens slowly and symptoms occur over time. NPH happens most often among the elderly.
- Hydrocephalus ex-vacuo results from brain damage caused by head injury or stroke. In these cases, brain tissue around your ventricles shrinks. CSF builds up in your ventricles to fill in the extra space. Your ventricles are enlarged, but pressure in your head usually remains normal.
Another word you may see or hear when learning about hydrocephalus is ventriculomegaly. Ventriculomegaly is the term used when the ventricles of a fetus’s brain are enlarged. Hydrocephalus may be the cause of the ventriculomegaly, but there are other reasons this enlargement might happen.
Symptoms and Causes
What causes hydrocephalus?
Hydrocephalus can develop for a number of reasons. Hydrocephalus may be congenital or acquired.
A combination of genetic and environmental factors during fetal development causes congenital hydrocephalus. “Congenital” means present at birth. The most common causes of congenital hydrocephalus are:
- Spina bifida and other brain and spinal cord (neural tube) defects.
- A narrowing of the small passage between the third and fourth ventricles of your brain (aqueductal stenosis).
- Complications of premature birth, such as bleeding within ventricles.
- Infections during pregnancy, such as rubella, that can cause inflammation in fetal brain tissue.
Acquired hydrocephalus develops at any point after birth and can affect people of all ages. The most common causes of acquired hydrocephalus are:
- Head trauma.
- Stroke.
- Brain or spinal cord tumors.
- Meningitis or other infections of your brain or spinal cord.
In addition, hemorrhage or complications of surgery may cause normal pressure hydrocephalus. Many people develop NPH without an obvious cause.
What are the symptoms of hydrocephalus?
Symptoms of hydrocephalus vary with age. It can also depend on how far along the disease is (disease progression). It also varies with how well a person tolerates the CSF buildup.
Symptoms in infants may include:
- Unusually large head.
- Bulging soft spot (fontanel) on top of your baby’s head.
- Downward gaze of your baby’s eyes (sun-setting eyes).
- Vomiting.
- Sleepiness.
Symptoms in older children may include:
- Headache.
- Nausea and vomiting.
- Vision problems.
- Developmental delays.
Symptoms in adults may include:
- Headache.
- Nausea and vomiting.
- Vision problems.
- Feeling tired.
- Problems with balance and coordination.
- Short-term memory loss.
Symptoms in older adults may include:
Diagnosis and Tests
How is hydrocephalus diagnosed?
Hydrocephalus is diagnosed through a neurological evaluation. Your healthcare provider may use brain imaging techniques such as ultrasounds, computer tomography (CT) or magnetic resonance imaging (MRI).
Other tests are often performed in adults to diagnose the condition. These tests may include:
- Spinal tap (lumbar puncture).
- Intracranial pressure monitoring (ICP), which uses a small pressure monitor inserted into your brain to measure pressure.
- Fundoscopic exam, which uses a special device to view your optic nerve at the back of your eye.
Management and Treatment
Can hydrocephalus go away on its own?
No. If left untreated, hydrocephalus can be fatal. Early diagnosis and successful treatment improve the chance for a good recovery
Myelomeningocele is the most severe form of spina bifida, a birth defect occurring when the spine and spinal canal fail to close completely during the first month of pregnancy. This results in a fluid-filled sac—containing spinal cord tissue and nerves—protruding from the baby’s back. It causes lifelong physical, neurological, and bowel/bladder dysfunction, requiring early surgical repair.
National Institutes of Health (.gov) +4
Key Aspects of Myelomeningocele
- Symptoms: A visible sac on the lower back, paralysis or weakness in legs, loss of bowel/bladder control, and reduced sensation.
Causes & Risks: While often unknown, it is likely caused by a combination of genetic and environmental factors
. Low folic acid levels in the mother before/during pregnancy, obesity, diabetes, and certain anti-seizure medications are known risks
.
Long-term Outlook
While many children survive with the condition, they usually require ongoing, multidisciplinary care, including physical therapy, orthotics, or wheelchairs. The level of disability depends on the location and severity of the spinal