Hydrocephalus
The same word names two very different situations: parents who are told their baby has large ventricles, and a family watching an older relative walk worse and worse and forget things. This page is written for both.
The brain floats in a fluid it makes itself, and which is replaced several times a day. That fluid circulates through internal cavities — the ventricles — flows out into the space surrounding the brain and the spinal cord, and is finally reabsorbed into the blood.
Hydrocephalus is what happens when that circuit falls out of balance and the fluid builds up. It is not "water on the brain", although it is sometimes called that: the brain is intact; what has changed is the plumbing.
And because that plumbing can fail at any age, the word names two very different stories.
The first story: a baby
Sometimes it is picked up before birth, on a scan showing the ventricles larger than expected. Sometimes in the first few months, because the head is growing faster than it should, the fontanelle is tense, the baby vomits, is irritable or very sleepy, or the eyes tend to look downwards.
The first thing to know is that "ventriculomegaly" on a prenatal scan does not amount to hydrocephalus. There are mild degrees that resolve on their own and leave no consequences. Follow-up exists precisely to tell one from the other, and that wait — distressing as it is — is the right course.
In Latin America the incidence of congenital hydrocephalus is estimated at 316 per 100,000 births, close to five times that of the United States and Canada. Worldwide, some 400,000 new paediatric cases are calculated each year.
The second story: an older adult
Here the picture is more treacherous, because it looks like growing old.
There are three symptoms and they usually appear in this order: walking, thinking and bladder control. First the person walks differently: short steps, feet stuck to the floor as if magnetised, difficulty setting off, difficulty turning, falls. Then the mental slowing begins: forgetting things, taking longer to answer, losing initiative. And last, urgency to pass urine, and sometimes incontinence.
This is called normal pressure hydrocephalus, and the trouble is that it is almost always mistaken for "old age", for arthritis or for dementia. The numbers say otherwise:
- It affects 3.7 per cent of people over 65, and 8.9 per cent of those over 80. Almost one in ten.
- More than 80 per cent of well-selected patients improve once a shunt is placed.
- It is enormously underdiagnosed. In a Swedish population study, of 1,238 people assessed, some twenty-six met the criteria and only two had a shunt in place.
That contrast is the reason this page exists. It is one of the very few causes of cognitive decline that has a treatment, and it is missed all the time.
There is an important qualification, and it is the one that prevents false hope: the symptom that responds best is walking. Cognition improves less, and continence less still. The earlier it is treated, the better the result tends to be.
When not to wait
In a baby or a child:
- A head growing faster than the check-ups say it should, or a tense, bulging fontanelle.
- Repeated vomiting, irritability that will not settle, unusual sleepiness, refusing feeds.
- Eyes that persistently turn downwards.
In anyone who already has a shunt in place, at any age:
- Headache, vomiting, sleepiness or irritability coming back: that is the pattern of a shunt that has stopped working.
- Fever with redness or pain over the course of the catheter, under the skin.
- In a child with a shunt, any deterioration in general condition deserves a same-day appointment.
In an adult:
- Rapid deterioration of consciousness, severe headache with vomiting, or a sudden change in walking.
How it is treated
There are two routes, and which one applies depends on the type of hydrocephalus.
The shunt. A fine catheter enters a ventricle and connects to a valve placed under the skin of the head, and to a tube that runs down through the neck and the chest to the abdomen, where the surplus fluid is reabsorbed. All of it sits below the skin and nothing shows. Modern valves can be adjusted from outside, without touching the patient.
Endoscopic ventriculostomy. When the blockage sits at one specific point, a new opening can be made with an endoscope so the fluid takes another route, with nothing implanted. It is not suitable for every case, but when it is, it spares living with a device.
Two things have to be said about shunts at the same time, because both are true. They work, and they change lives. And they are mechanical devices that can block, become infected or lose their calibration, above all in the first year and above all in children. Living with a shunt means knowing how to recognise the signs that it has stopped working. That is one of the reasons this practice built a shunt valve simulator, which is in the Lab section.
What you will hear that is not true
"Enlarged ventricles on the MRI means hydrocephalus." Not necessarily. When the brain shrinks, the ventricles take up the space left behind: this is called ex vacuo hydrocephalus and it is not true hydrocephalus. It does not improve with a shunt. Telling one from the other is a central part of the assessment.
"It is dementia, it is old age, there is nothing to be done." Almost 9 per cent of people over 80 meet the criteria for normal pressure hydrocephalus, and more than 80 per cent of well-selected patients improve. It is worth ruling out before accepting that nothing can be done.
"Hydrocephalus is always there from birth." It can appear at any age: after a haemorrhage, after meningitis, after a tumour, after a head injury, or with no identifiable cause in an older adult.
"A shunt is for life, and a shunt always fails." Neither half is accurate. Many people live for decades with the same shunt. And yes, complications do happen; that is why follow-up is part of the treatment, not an add-on.
What will happen at the appointment
In a baby: measuring the head and comparing it with previous check-ups — the curve matters more than any single value — examining the fontanelle and the eyes, and a scan. In the smallest babies, ultrasound through the fontanelle avoids radiation.
In an adult: examination of walking, almost always filmed or timed so it can be compared later, cognitive assessment and an MRI. And very probably a lumbar puncture tap test: fluid is drawn off and walking is measured again over the following hours. If it improves, that is a good predictor that a shunt will work. It is the most useful test there is for making the decision.
Questions worth writing down before you go
- Is this true hydrocephalus, or large ventricles from shrinkage of the brain?
- Which type of hydrocephalus is it, and what caused it?
- Is endoscopic ventriculostomy an option, or is a shunt needed?
- Can the tap test be done before deciding?
- Which symptom do you expect to improve, and which one probably will not?
- Which signs do I have to learn to recognise if a shunt is placed?
The questions people ask most
Is hydrocephalus in adults curable?
Normal pressure hydrocephalus is not cured in the sense of disappearing, but it is treatable: more than 80 per cent of well-selected patients improve with a shunt. The symptom that responds best is difficulty walking; cognition improves less, and the earlier it is treated, the better.
I was told I have enlarged ventricles. Is that hydrocephalus?
Not always. The ventricles also enlarge when the brain shrinks, and that — ex vacuo hydrocephalus — does not improve with a shunt. Telling one situation from the other means putting together the pattern of the symptoms, the examination of walking and, often, a tap test.
What is a ventriculoperitoneal shunt and how does it work?
It is a three-part system: a catheter in the ventricle, a valve under the skin of the head that regulates the flow, and a tube that runs down to the abdomen. It diverts the surplus fluid so that it is reabsorbed elsewhere. All of it stays below the skin, and current valves are adjusted from outside with a magnet, with no needle and no operation.
How do I know if a shunt has stopped working?
The signs are the return of the symptoms the shunt had resolved: headache, vomiting, sleepiness, irritability in a child, or difficulty walking coming back in an adult. Also fever with pain or redness over the course of the catheter. With any of these, seek advice the same day.
Can hydrocephalus be detected during pregnancy?
Yes, ultrasound can show the ventricles enlarged. But "ventriculomegaly" is not the same thing as hydrocephalus: mild degrees frequently resolve on their own and leave nothing behind. Follow-up ultrasound, and sometimes a fetal MRI, serve to tell them apart.
Can a child with a shunt live a normal life?
Generally yes, school and most sports included. What tends to be avoided are contact sports and those with repeated blows to the head. The specific restrictions depend on each case, and it is worth having them in writing.
Can you die from hydrocephalus?
Untreated acute hydrocephalus is a serious situation, and the sudden failure of a shunt is too. That is why the system of warning signs matters so much. But chronic hydrocephalus, treated and monitored, is not in itself a condition that shortens life.
What is an endoscopic ventriculostomy?
It means using an endoscope to make a new opening in the floor of the third ventricle, so the fluid takes another route with no need to implant any device. It is the best option when the blockage sits at one specific point in the circuit. It is not suitable for every case, and it is worth asking whether yours is.