Long Term Care of Shunts
Periodic visits to the neurosurgeon are desirable to monitor the shunts function over time. Generally, it is obvious when a shunt is malfunctioning. Signs of an overt failure would include recurring, intensifying headache and /or irritability, lethargy, nausea/vomiting with loss of appetite, and loss of the ability to look upwards. Subtle symptoms can also suggest a problem with the shunt. These would include an unexplained decline in work or school performance, pain or redness along the shunt tract, or fever of an unexplained origin. An examination will frequently uncover signs of increased pressure within the head when a shunt malfunctions.
Plain x-rays will demonstrate rupture or disconnection of the shunt's catheters and CAT or MR scans can demonstrate interval change in ventricular size. When a CAT or MR scan is performed, it is imperative to compare it to a scan which was taken when the child was feeling well and the shunt was working properly (see example). It is not unusual for scans thought to initially be normal to in fact show an interval enlargement of the fluid spaces due to malfunctioning of the shunt. This can only be appreciated when current scans taken when the individual was symptomatic are compared to scans done when he or she was feeling well. Blood tests can be used to see if there are signs of an inflammatory process within the body as would occur with an infection and CSF can be withdrawn from the shunt's reservoir to look for signs of infection within the CSF.
A properly functioning shunt does not require manipulation of the pump. If the system is draining sluggishly a decision is sometimes made to have the family speed it up with the pump. But this is a temporary expedient; revision due to one of the shunt's element's malfunction is almost inevitable. In addition, the pumping of the shunt to evaluate its function can be misleading. There is often little correlation between function and what is noted on depressing the pump. If a child is asymptomatic there is no need to manipulate the apparatus, and this may in fact cause problems with drainage.
Shunts commonly function for many years without problems of any sort. And so, of course, parents often inquire whether the child "still needs the shunt." The answer is almost always yes. The overwhelming majority of children will remain shunt-dependent all their lives. Possible exceptions to this rule are those with spina bifida; for unknown reasons approximately 20% of them develop arrested hydrocephalus.
In a few patients, serial abdominal X-rays will reveal that the shunt has become distracted from the peritoneal cavity. A decision must then be made as to whether or not the tube is to be lengthened. If the CAT scan discloses a small ventricular system there is no question that the shunt is functional, and it is reasonable to lengthen it before the child becomes symptomatic. Arrested hydrocephalus is invariably associated with moderately to markedly enlarged fluid spaces, so that normal or small ventricles are always indicative of shunt dependency.
If a child is diagnosed as having arrested hydrocephalus, it is incumbent on the physician to ensure that no damage to the nervous system occurs through incorrect diagnosis. These patients should have annual neuropsychological testing, looking for a subtle decline in higher cortical function. Any suspicion of an evolving deficit mandates an immediate shunt revision.
Many years ago, when shunts were made of relatively brittle materials, there was a tendency to be conservative about encouraging sports or other vigorous activity. However, it has become very clear that present-day shunts are not easily fractured, and limiting sports in children who are physically able to engage in them is a significant emotional burden. We encourage our patients to participate in soccer, tumbling, gymnastics, or anything else they may choose.
Children with shunts are, of course, vulnerable to all the usual illnesses of childhood. When these are accompanied by high fever, it is sometimes suggested that the shunt be tapped to exclude the possibility of infection of the shunt. However, it should be kept in mind that 95% of shunt infections occur within 3 to 5 days of surgery, so that this is a most unlikely etiology.
Fever persisting longer than expected in the absence of an obvious explanation may occasionally call for shunt aspiration in spite of this unlikelihood. If so, it is essential that the sample be obtained from the pump rather than with a spinal tap. The latter will frequently test negative even when there is an active shunt infection.
It should also be pointed out that shunt-dependent children are very prone to headaches during febrile illness or vigorous activity, and this should only be a source of concern when the headaches persist and/or worsen.
The presence of a shunt in a female is not a contraindication to her becoming pregnant, and, if this is her desire, she should be supported in it. When a woman with a shunt becomes pregnant, she can experience an increase in the frequency and intensity of headaches due to changes in her intravascular volume and, as a result, her cerebral blood flow. Because this state can be difficult to differentiate from a shunt malfunction, it is wise to obtain a MRI scan at the beginning of pregnancy to be used as a baseline for comparison should symptoms of increased intracranial pressure arise.