Shunt

What is a Shunt?
A shunt is simply a device which diverts the accumulated CSF from the obstructed pathways and returns it to the bloodstream. It consists of a system of tubes with a valve to control the rate of drainage and prevent back-flow. It is inserted surgically so that the upper end is in a ventricle of the brain and the lower end leads either into the heart (ventriculo-atrial) or into the abdomen (ventriculo-peritoneal). The device is completely enclosed so that all of it is inside the body. The fluid which is drained into the abdomen passes from there into the bloodstream. Other drainage sites such as the outer lining of the lungs (ventriculo-pleural shunt) can also be used.

A shunt consists of: A Catheter: hollow flexible tube inserted into a ventricle in the brain or into the space around the spinal cord, depending on the type of hydrocephalus that the child has. A valve: which controls the amount, pressure and direction of CSF flow (so that CSF can only flow away from the brain). A tube leading from the valve under the lining of the abdominal cavity called the peritoneum where the CSF can be absorbed.

Possible Complications
In most cases, the shunts are intended to stay in place for life, though alterations or revisions might become necessary from time to time. The tube or catheter may become too short as the individual grows and an operation to lengthen it might be necessary.

Occasionally, as with any implant, there can be mechanical failure. Also, it is important to be aware that problems can occur with blockage or infection of the shunt.
 
What Symptoms Should be Looked for?
These vary enormously between individuals. Previous personal experience of a shunt problem is usually a reliable guide as to what to look for.
 
Possible signs of acute shunt blockage may include: vomiting, headache, dizziness, photophobia (sensitivity to light) and other visual disturbances, drowsiness and fits.
 
Possible signs of chronic shunt blockage may include: fatigue, general malaise, visuo-perceptual problems, behavioural changes, decline in academic performance, being just 'not right' from the carer's point of view.

Medical advice should be sought from your neurosurgical unit if a shunt blockage is suspected, within four hours of acute symptoms occurring.

In shunt infections, symptoms vary with the route of drainage. In ventriculo-peritoneal shunts, the symptoms often resemble those of a blockage. This is because the shunt becomes infected and the lower catheter is very often then sealed off by tissue. There may be accompanying fever and abdominal pain or discomfort.

In ventriculo-atrial shunt infections, fever is present in most cases though often intermittently. Anaemia is frequently present, and sometimes skin rashes along with joint pains. In contrast to ventriculo-peritoneal shunts, such infections may not appear for months or years after the operation when they were contracted. Various tests can be carried out for shunt infections and medical advice should always be sought if an infection is suspected. 

How are shunt problems treated?
Shunt blockages which are causing illness usually require an operation to replace or adjust the offending part of the shunt. Shunt infections are usually treated by removal of the whole shunt and a course of antibiotics before insertion of a new system. Modern approaches to antibiotic therapy mean that such treatment can be expected to succeed in most cases. 

Hydrocephalus and fits
Richard Hayward, consultant neurosurgeon, writes:
"Patients with Hydrocephalus sometimes have fits. The fits are not due to the Hydrocephalus itself but are usually associated with an underlying cause (meningitis, abnormal development of the brain, neonatal haemorrhage etc). As a general rule, fits in patients with Hydrocephalus should be treated in the same way as those that occur in children who do not have Hydrocephalus."