What is hydrocephalus?
Hydrocephalus, when broken down to its word roots, hydro and cephalus, literally means ‘water in the brain’. As the picture alongside shows, this can lead to abnormal shaping of the forehead. The accumulation of water in the brain has to do with the flow of cerebrospinal fluid (CSF). Under normal circumstances, there is a balance between the flow of the fluid within the central nervous system and the resorption of the CSF within the arachnoid granulations. However, if there is a blockage, the fluid can build up.
There are several causes that can trigger hydrocephalus:
- Impaired flow of CSF
- Impaired resorption of CSF back into the tissues
- Tumours of the choroid plexus
- Overproduction of CSF
The first two circumstances are fairly common, and the other two are relatively rare.
Enlargement of the head as a result of hydrocephalus only tends to happen in kids because the skull is not fused together like it is in adults. The skulls of kids are held together only by cranial sutures, which are flexible in nature. In adults, hydrocephalus acts differently: it can result in either non-communicating or communicating hydrocephalus. Noncommunicating hydrocephalus happens as a result of a blockage of CSF: a portion of the ventricles enlarges whilst the rest of the brain remains unchanged. In communicating hydrocephalus, however, the entire area of the ventricles become enlarged due to the inabiilty of the brain to resorb the excess CSF.
Another type of hydrocephalus is known as hydrocephalus ex vacuo. This often happens as a result of degenerative diseases or infarcts. As a result of loss of brain tissue, the ventricles can often dilate and as compensation, the levels of CSF can increase.