Copyright: Prof Jas. Mundie
Although I have previously posted about hydrocephalus on the Facebook page’s ‘Fact of the Day’, I was inspired to discover more about this distinctive condition after a recent visit to Surgeon’s Hall Museum, Edinburgh. Full of fascinating pathological specimens, the congenital hydrocephalic infant skulls on display are hard to miss with their domed craniums, characteristic of bodies more alien than our own.
The term hydrocephalus comes from the Greek words ‘hydro’ meaning water and ‘cephalus’ meaning head. Translated literally, it means ‘water on the brain’. Hydrocephalus is in fact a build up of cerebrospinal fluid within the brain.
10 Facts About Cerebrospinal Fluid
- Cerebrospinal fluid (CSF) is a clear, colourless liquid that fills and surrounds the brain and the spinal cord, acting as a lubricator against bone and a shock absorber against trauma to our body’s most important system
- It is formed primarily in the ventricles of the brain and circulates via a series of chambers
- It helps to maintain a constant pressure within the cranium by decreasing in levels as the volume of blood or brain tissue increases and vice versa
- When cerebrospinal fluid is in excess, it is moved away from the brain by absorption into the bloodstream by a specialised tissue called the arachnoid villi which act as a one way valve
- It transports metabolic waste products, antibodies, chemicals, and products of disease away from the brain and spinal cord into the bloodstream
- It has a slightly alkaline pH
- It is about 99% water.
- There are approximately 100-150ml of CSF in the average adult human body
- It is produced continuously, and it is completely replaced every six to eight hours
- Analysis of CSF can diagnose a number of diseases. Samples can be obtained by lumbar puncture or spinal tap by inserting a needle into the lumbar region of the lower back
Hydrocephalus can develop where there is a blockage in one of the ventricles, preventing excess CSF from moving out of the brain, where the arachnoid villi aren’t functioning properly and CSF is unable to filter into the blood vessels or, in some rare cases, when the brain produces too much CSF.
Congenital hydrocephalus can occur due to the restriction of flow of CSF caused by brain defects in the developing baby which can be due to certain health conditions like the most serious type of spina bifida. It can also occur in premature babies which experience bleeding in their brain, blocking the flow of CSF and causing hydrocephalus. Other potential causes include X-linked hydrocephalus where the condition occurs as a result of a genetic mutation, rare genetic disorders such as Dandy Walker malformation and arachnoid cysts between the brain or spinal cord and the arachnoid membrane.
Acquired hydrocephalus which develops in adults or children is most often occurs by injury or illness that results in a blockage between the ventricles of the brain. Possible causes include bleeding inside the brain, blood clots inside the blood vessels of the brain, meningitis, tumours, head trauma and stroke.
The physical symptoms of hydrocephalus are distinctive, but can vary with age, tolerance and progression of the disease. The characteristic, unusually large cranium is caused by the infant skull’s ability to expand to accommodate the build up of excess CSF. The sutures of the skull, which are not yet closed, provide the flexibility in the cranium to ‘grow’ with the expanding volume. The scalp may be thin with visible veins and the fontanelle (soft spot on the top of a baby’s head) may be tense or bulging. The eyes can also appear to be looking downwards due to nerve damage which can affect the muscles of the eye.
Without treatment, it is thought that up to 6 in 10 people with hydrocephalus would die. However, most children with hydrocephalus that survive past the age of one will have a fairly normal life span. Patients usually require prompt treatment to reduce the pressure on their brain either by neuroendoscopy or shunt surgery which involves implanting a thin tube into the brain to run the excess cerebrospinal fluid to another part of the body, usually the abdomen, where it can be absorbed into the blood stream.
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