What is it about ?
The brain and spinal cord are soft, fragile tissues that are protected from shock by cerebrospinal fluid. This fluid, about 500 ml per day, is produced in the brain cavities from the blood. It then circulates around the brain and spinal cord. Then he goes back to the blood. So there is a constant production and flow of cerebrospinal fluid and a balance between production and elimination.
We talk about hydrocephalus when there is too much cerebrospinal fluid in the brain. Fluid accumulates most often as a result of blocked elimination. The pressure increases, which is very dangerous for the brain.
The flow of cerebrospinal fluid can be restored by placing a bypass or shunt. It is a kind of connection, through tubes, between the cavities that contain the cerebrospinal fluid (ventricles of the brain) and the belly cavity (ventriculo-peritoneal bypass) or the heart (ventriculo-atrial shunt).
Complications are possible:
- obstruction of the bypass;
- infection;
- evacuation of too much cerebrospinal fluid;
- increased risk of bleeding between the meninges.
How to recognize it?
A sharp increase in pressure in the brain causes headaches and vomiting and eventually causes drowsiness. In severe cases, this can lead to a coma.
If the pressure is normal and there are no severe symptoms of high pressure, a slowly progressing syndrome develops, with symptoms such as dementia, trouble walking, and bladder problems.
How is the diagnosis made?
If hydrocephalus is suspected, the doctor will always refer you to a neurologist for a thorough examination and, among other things, a CT scan and / or MRI of the head.
What is a derivation?
The lead consists of two silicone catheters which are connected on either side of a valve. At one end, a catheter is inserted into the brain cavity through a hole in the skull (trepanation). At the other end, a catheter is passed under the skin into the stomach. Another option is to unblock the catheter into the heart via the deep vein in the neck. The valve between the catheters prevents excessive flow of cerebrospinal fluid through the shunt. Here is an overview of the possible complications of the bypass:
- The lead may become blocked, preventing the flow of cerebrospinal fluid. The cause could be, for example, a blood clot or scar tissue that closes the catheter. As a result, the pressure of the cerebrospinal fluid increases, creating a situation that can be fatal within hours. The bypass must then be checked and unblocked urgently.
- The catheter can be exposed to the skin and become infected. This is accompanied by fever and the spread of infection through the blood. In this case, the bypass must be replaced with a new one.
- Sometimes the valve does not work properly, and too much cerebrospinal fluid is leaking out. The brain cavities can then collapse. The main symptom is headache. The valve must be adjusted or replaced.
- The bypass makes the patient more vulnerable to chronic bleeding just below the outer meninges. If this happens, the blood is removed by trepanation.
- Finally, the catheter can cause discomfort under the skin. In this case, the treating neurosurgeon should be consulted.
Want to know more?
- Hydrocephalus – better understanding the disease and its treatments – CHU Montreal
- Reduce the pressure in the skull with a drain – The external ventricular drain – CHU Montreal
- Caring for a loved one with a drain in the skull – The external ventricular drain – CHU Montreal
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