Hydrocephalus
Hydrocephalus, also known as “water on the brain” is a condition in which there is more than normal cerebrospinal fluid around the brain and spinal cord. The cerebrospinal fluid acts as a cushion between the brain and spinal cord, provides nutrients and removes waste products.
Hydrocephalus may be present from birth (congenital) or develop later (acquired).
- Congenital Hydrocephalus: it is present from birth, but could be detected years later. It develops when the brain and surrounding structures develop abnormally. The exact cause is unknown, although the factors contributing to this could include genetic and infectious factors during pregnancy.
- Acquired hydrocephalus: results from injury or disease at birth or later, including infections in the brain and spinal cord, hemorrhage (bleeding) of the blood vessels of the brain, severe brain injury, brain tumors or cysts. Hydrocephalus also occurs when the injury is unknown cause.
Hydrocephalus can be classified according to their cause:
- Obstructive hydrocephalus (without communication) is caused by a blockage in the system of the brain cavities (ventricles). The blockage prevents the cerebrospinal fluid flow (“communicate”) with the area that surrounds the brain and spinal cord (subarachnoid space), as it should normally. Obstructions can be present at birth or may occur later. One of the most common types is aqueductal stenosis, which occurs due to narrowing of the aqueduct of Sylvius, a channel that connects two of the ventricles.
- Non-obstructive hydrocephalus (with communication): occurs as a result of problems with production or absorption of cerebrospinal fluid. One of the most common cause is bleeding into the subarachnoid space. Communicative hydrocephalus may be present at birth or occur later.
Another type of hydrocephalus called normal pressure hydrocephalus is a type of non-obstructive hydrocephalus acquired in which the ventricles are enlarged but not under pressure. The normal pressure hydrocephalus is common in older adults. It could be the result of injury or illness, but in most cases the cause is unknown.
Premature babies born before 34 weeks or weighing less than 4 lbs (1.8 kg) has a high risk of bleeding from blood vessels in the brain. Severe bleeding can lead to obstructive hydrocephalus or obstructive, depending on location and extent of bleeding.