Acta Neurochir (Wien) (2004) 146: 1175–1176 DOI 10.1007/s00701-004-0375-4

Personal Comment What should we be doing for the ‘‘teenage shunt’’? R. Hayward Department of Neurosurgery, Great Ormond Street Children’s Hospital, London, UK Published online September 20, 2004 # Springer-Verlag 2004

The point I want to discuss is a more than an academic one. The child who has had a shunt inserted for the management of hydrocephalus lives under a watchful, sometimes paranoid, parental eye. Any illness that suggests the slightest possibility of shunt blockage is likely to be drawn swiftly to medical attention. But the child grows up, becomes an adolescent, the adolescent becomes an adult with, at each birthday, increasing independence from (in the young person’s dreams) everyone. School gives way to (in the UK) a pre-university gap year often spent in remote corners of the planet and then to university itself where accommodation may start in anonymous halls of residence but is likely to end in shared student apartments. Throw in alcohol and long vacations – not to mention another, hopefully, 70 years of life and perhaps an attitude of I’m not going to tell anyone I’ve got hydrocephalus, and it’s not hard to see how the question of whether or not our young person should be living under the never absent possibility of neurological disability or even death from acutely raised intracranial pressure is clearly of great importance. The majority of our new ‘‘shunt’’ patients are under one year of age at first diagnosis. We know that over 50% will have needed a shunt revision – often more than one – by the time they are ten but a lucky few will reach the age when they will be passing from a paediatric to an ‘‘adult’’ unit without having undergone any further surgery. And their parents will ask, ‘‘Is he=she still using the shunt?’’ We know from experience that the majority still are but if x-rays are taken of the system, some will

reveal fractures, disconnections or obvious shortness of the distal tubing that strongly imply that the patient’s own ‘‘pathways’’ are now responsible for effective CSF flow. For this group the message – and the management – is straightforward. Externalise the lower end of the system and if ‘‘no-flow’’ is confirmed, wait 48 hours with the tubing clamped off and if all remains well, remove the redundant valve and distal tubing – leaving the ventricular catheter well alone for fear of triggering a potentially disastrous bleed from where it is probably stuck to choroid plexus. Why remove the valve and distal tubing? With time Silastic corrodes. Indeed if the system has fractured or become disconnected this was probably due to corrosion anchoring the previously ‘‘non-stick’’ tubing in the subcutaneous tissues – a problem seen mostly around and just above the clavicle. It can lead over the years to an unsightly bow-stringing of the tubing in the neck and sometimes to tender lumps along it due to foreign body reactions. Because of this removal of valve and distal tubing may can require more incisions than were needed originally to insert them but it’s an option the patient should certainly be offered. If our teenager has had a revision because of blockage in the recent past then the answer to whether the shunt is still needed is pretty obvious. So, what are our responsibilities when there is reasonable evidence that the shunt is still functioning? Of prime importance is to make absolutely sure that the patient accepts the possibility that at any time they may require access to sophisticated emergency medical care (which means facilities for brain scanning and neurosurgery). Sure,

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the blockage risk for a shunt that has had no problems for a year or more may have fallen to an annual rate of 5% or so but it’s a hazard that isn’t going to go away. Perhaps they’ll be discovered unconscious in their students’ residence after a hard night’s partying and in no position to provide a clinical history. Should a MedicAlert bracelet or some such tag should be mandatory in addition to the student health service receiving specific information about shunts and the hazards associated with their failure? Another possibility. We all have patients whose shunts have not required revision since the day of their insertion, or there have been no shunt revisions for, say, the last 10 years but there’s no evidence on x-rays of any shortening (lower end out of the peritoneum, for example), disconnection or fracture either. The patient and family still ask, Is the shunt really needed? Unfortunately for those who have had the most gratifying clinical and radiological (scan) response to the original shunt insertion, the answer remains, yes the shunt is probably still functioning. But how can we be certain? Again unfortunately, the only way of being absolutely sure is to bring the patient into hospital and block the shunt in some way (by exteriorising the lower end or putting a clip or ligature around the distal tubing, for example). If the patient starts complaining of headache and vomiting and becomes obtunded then you have the answer and either the clip=ligature is released or the exteriorised lower end unclamped. It’s a ‘‘test’’ I’ve been offering families for some years now and I can’t say I’ve had many takers! I can’t say that I blame them either. They may know already through grim experience the problems that can follow any surgical interference with a shunt and the adage If it ain’t broke don’t fix it is a hard one to argue with in this situation. But what if there was something you could offer in lieu of the shunt if this ‘‘test’’ confirms that the patient is still shunt dependent? Here’s another scenario. The in-patient blocking=clamping of the system results not only in the characteristic symptoms of shunt blockage but also in a sufficient increase in size of the ventricular system to make an endoscopic third ventriculostomy (ETV) a possibility. This is a procedure whose success becomes increasingly independent of the aetiology of the hydrocephalus as a patient gets older and we all have some experience of offering it as an alternative to shunt revision in cases of ‘‘natural’’ shunt failure. Why not offer it now?

R. Hayward: What should we be doing for the ‘‘teenage shunt’’?

But if it works, will it allow the patient to be ‘‘off the hook’’ from recurrence of symptomatic hydrocephalus for the rest of his or her life? The answer is no. Although revision rates following ETV appear to be lower than for shunts, there is no doubt that they do block and that when they do so the symptoms can come on with frightening – even life-threatening – rapidity. Also the ETV procedure itself, unlike a shunt insertion, carries a small but definite operative mortality, usually from damage to the basilar artery and its immediate tributaries. It’s a complex situation but here’s what I propose. 1. For those shunted patients previously cared for in a primarily paediatric neurosurgical service and who are now growing out of the age range of that service, there should be a formal transfer of care to their ‘‘adult’’ service with a full explanation to patient and family alike of their future responsibilities – and preferably with appropriate literature provided. 2. All patients who have not had recent neuro-imaging should have x-rays of the shunt system and a brain scan (CT or MRI) to determine the status of their system prior to this transfer. 3. Those whose imaging suggests that the shunt is unlikely to be working should be offered the opportunity to confirm this – and to have the system removed (except for the ventricular catheter). 4. Those whose systems are intact but who have had no problems for many years should be offered the opportunity of a ‘‘trial of blockage’’, with an ETV to follow if continuing dependency upon some form of CSF diversion is confirmed – and shunt removal if it is not. Most will probably refuse but in an age (rightfully) of consensus medicine it is a topic that deserves to be discussed. 5. All patients with functioning shunts (confirmed or suspected) should wear some form of medical identity bracelet as they enter adult life. Indeed a good case can be made for anyone who has ever been treated for hydrocephalus wearing one. After all, ETV’s block and who’s to say that a patient demonstrated to be independent of their shunt system at 16 may not decompensate some 10 years later.

Correspondence: Richard Hayward, Department of Neurosurgery, Great Ormond Street Children’s Hospital, Great Ormond Street, London, WC1N 3JH, UK. e-mail: [email protected]