Commonly referred to as water on the brain, hydrocephalus is a condition where an excess of cerebrospinal fluid (CSF) builds up in the brain widening the ventricle spaces, putting potentially harmful pressure on the brain tissue.
The ventricular system is made up of four ventricles each connected by narrow passages. In a normal situation, CSF flows through the ventricles, exits into closed spaces that serve as reservoirs at the base of the brain, bathes the surfaces of the brain and spinal cord, and then reabsorbs into the bloodstream.
CSF is critical to the brain as it keeps the brain buoyant and cushioned acting as a shock absorber. As it flows it removes waste and delivers nutrients. Lastly as CSF flows between the cranium and spine it compensates for changes in the amount of blood that flows within the brain. That critical balance between CSF which is made continuously and the absorption of CSF is a delicate balance. Too much CSF due to a block within the normal flow or absorption and the result is the medical condition hydrocephalus.
Just as there are several types of hydrocephalus, there are several ways it occurs. Congenital means that hydrocephalus was present at birth and is a result of either genetics, or a developmental influence that occurred during development. Acquired hydrocephalus develops at any point in time, from birth on. It is a result of injury or disease.
Hydrocephalus can be either communicating or non-communicating. Communicating means the flow of CSF is blocked after it leaves the ventricles. The term communicating is used because the CSF can still flow between the open ventricles. In non-communicating or obstructive the flow of CSF is blocked along the narrow passages connecting the ventricles.
Because hydrocephalus can occur due to accident or traumatic brain injury, there are a couple of forms highly noted in older patients. Hydrocephalus ex-vacuo is the result of brain damaged that causes the brain tissue to shrink. An increase of cerebrospinal fluid in the brain’s ventricles may result from any number of factors, including infection, tumor, hemorrhage, head trauma, or complications from surgery.
How frequent hydrocephalus occurs is difficult to say due to late onset forms. Estimates in babies born with hydrocephalus is one or two for every 1,000 births. These babies may have a genetic defect that result in neural tube defects, had traumatic head injury during birth, have other trauma that results in brain damage.
If not detected before birth, the most common means for spotting hydrocephalus is:
- noticing a large growth in head circumference
- unusually large head at birth
A baby may also show outward signs such as
- a downward deviation of the eyes (known as sun setting)
- failure to develop skills in a timely fashion
Hydrocephalus is diagnosed through clinical neurological evaluation and by using cranial imaging techniques such as ultrasonography, CT, MRI, or pressure-monitoring techniques.
Left untreated hydrocephalus is fatal. A child with hydrocephalus may need a shunt to help remove the build up of fluid. Shunting has a high level of success and individuals with shunts may live a normal life expectancy. A child with hydrocephalus may have other conditions that effect their educational, physical, social and motor control development. For this reason, children with hydrocephalus can benefit greatly from individually designed therapies tailored to their specific learning needs.
For more information on hydrocephalus, please visit the Hydrocephalus Association website.