Hydrocephalus is a condition in which excess fluid builds up in your brain. The word hydrocephalus comes from the roots hydro meaning "water" and cephalus meaning "head." The fluid that accumulates is cerebrospinal fluid (CSF), a fluid that normally surrounds your brain and spinal cord.
In hydrocephalus, too much fluid builds up, causing abnormal enlargement of the cavities in the brain (ventricles) that contain CSF. Too much CSF in the ventricles can put too much pressure on the brain, potentially damaging the brain.
You can have hydrocephalus at birth (congenital hydrocephalus) or you can develop it later (acquired hydrocephalus). Hydrocephalus occurs in about 1 in every 500 children.
The outlook for people with hydrocephalus varies depending on how soon the condition is diagnosed, whether any other disorders are present and whether treatment is successful. Left untreated, progressive hydrocephalus is, with rare exceptions, fatal.
Signs and symptoms
Age, how far the disease has progressed and how well a person can tolerate increased CSF pressure all affect the signs and symptoms. Babies may better tolerate increased CSF pressure because the bones of their skulls haven't fused together yet, and thus their skulls have more flexibility to handle the pressure.
In infants, common signs and symptoms of hydrocephalus include:
Your child's skull consists of not one but several separate bones. Over the first year or two of life, these bones fuse to form a single protective bone mass. Until then, there's a soft spot (...
In older children and adults, common signs and symptoms of hydrocephalus include:
These are the most common signs and symptoms of progressive hydrocephalus. However, the signs and symptoms of hydrocephalus may vary from person to person.
Hydrocephalus results when the flow of CSF is disrupted or when your body doesn't absorb CSF properly. CSF provides a number of important functions, including acting as a cushion to protect your brain and bringing nutrients to your brain.
Inside your brain are four ventricles. CSF flows through the ventricles by way of channels that connect one ventricle to another. Once CSF passes through the ventricles, it flows into closed spaces (cisterns) at the base of your brain. Eventually, the CSF is absorbed into your bloodstream. Keeping the production, flow and absorption of CSF in balance is important to maintaining normal pressure inside your skull.
In adults, a variation of hydrocephalus called normal-pressure hydrocephalus may occur in which the CSF pressure is normal but the reabsorption of CSF is defective. In normal-pressure hydrocephalus, the ventricles of the brain are enlarged but not under high pressure. This type of hydrocephalus is most often seen in older adults and may be the result of injury or illness, but in the majority of cases the cause is unknown.
The causes of hydrocephalus fall into two main categories:
Doctors don't completely understand the specific causes of hydrocephalus. For congenital hydrocephalus, the causes may be genetic disposition or a developmental problem. The most common developmental problems that may lead to hydrocephalus include failure of the tissue surrounding the spinal cord to close properly (spina bifida) and herniation of the brain (encephalocele). For acquired encephalitis, the cause may be a disease or condition such as encephalitis, meningitis or a brain tumor that causes blood vessels in the brain to rupture and bleed. Or the cause may be a head injury.
Premature infants born before 34 weeks of gestation or weighing less than 4 pounds have a high risk of intraventricular hemorrhage in which severe bleeding within the ventricles of the brain can lead to hydrocephalus. Other problems that can occur during pregnancy may increase an infant's risk of developing hydrocephalus, including intrauterine infection or a disorder involving incomplete closure of an infant's spinal column (myelomeningocele).
Older children with increased risk of hydrocephalus include those with a history of congenital or developmental defects, lesions or tumors of the brain or spinal cord, central nervous system infections, bleeding in the brain, and severe head trauma.