What causes hydrocephalus?
There are several causes of hydrocephalus, including:
- It can develop before birth
- Develops in childhood or adulthood
- Inherited genetically
- Occurs with developmental disorders, including spina bifida and encephalocele
- Brain tumors
- Head injuries
- Bleeding in the brain (hemorrhage)
- Meningitis
The causes of hydrocephalus can be classified by types, including:
- Acquired hydrocephalus is present at birth, or develops in adulthood due to an injury or disease.
- Congenital hydrocephalus is present at birth; can happen during fetal development by an inherited genetic defect that blocks the flow of CSF; developmental disorders caused by birth defects in the brain, spine, or spinal cord; complications of premature birth such as bleeding within the ventricles; or infection during pregnancy such as rubella or syphilis that can cause inflammation in the fetal brain tissue.
- Communicating hydrocephalus occurs when the flow of CSF is blocked after it leaves the brain’s ventricles, but the CSF can still flow between ventricles. Buildup can also occur due to reduced flow or inadequate absorption of CSF into specialized blood vessels called arachnoid villi, or it can be caused by an abnormal increase in the amount of CSF produced.
- Normal-pressure hydrocephalus (NPH) is a type of communicating hydrocephalus that is most common in older people. It can be caused by bleeding in the brain’s CSF, head trauma, infection, tumor, or a complication of surgery. However, many cases of NPH have none of these factors present. With NPH the CSF increases slowly enough to allow tissues around the ventricles to compensate. This keeps the pressure inside the head from increasing, and spinal column pressure is normal. NPH causes problems with walking, bladder control, thinking and reasoning. It can be mistaken for Alzheimer’s disease. NPH accounts for more than 5% of all dementias.
- Non-communication (obstructive) hydrocephalus occurs if the flow of CSF is blocked along one or more of the narrow passages that connect the ventricles. This causes enlargement of the pathways upstream of the blockage and leads to an increase in skull pressure.
- Hydrocephalus ex-vacuo is a result of brain damage caused by stroke or injury, chiefly in adults. It can be caused when a degenerative disease (such as Alzheimer’s disease, stroke or trauma) causes the tissue around the ventricles to shrink, making the ventricles bigger than normal.