Information about hydrocephalus
In this page you'll find a brief information about hydrocephalus that I've collected
from the Internet. This is just a digest for those of you who are just curious. If you
have a child, or are expecting one, with hydrocephalus I recommend you to read
the original article by Dr Roger Bayston. There you'll find more detailed information
that includes symptoms for complications that may appear, treatments other than shunts and
causes for hydrocephalus. The article is in the Association
for Spina Bifida and Hydrocephalus homepage, in England, that has other important
information and some publications that might interest you.
You should also visit the Hydrocephalus
Association Homepage where you can find some resources and services for USA residents.
The term 'hydrocephalus' is from two Greek words meaning 'water in the
head'. In fact the 'water' is cerebrospinal fluid (CSF), a clear liquid which is produced
all the time in the cavities or ventricles inside the brain. It passes from one ventricle
to the next (four in all) through narrow pathways, then circulates around the surface of
the brain - a little also goes down the spinal cord - and is absorbed back into the
bloodstream. The absorption takes place through specialised veins inside the skull which
have a sieve-like surface. Though much slower than the circulation of the blood, the CSF
is constantly being produced, circulated and reabsorbed.
Hydrocephalus can result when either too much CSF is produced (very
rare), or when it is prevented from circulating or being reabsorbed. As in these
circumstances CSF is constantly produced but cannot get out, it accumulates and causes
raised pressure inside the brain. The ventricles swell and the brain tissue is stretched
and squashed. The skull bones in babies and young children are not fixed together as they
are in later life, and the pressure causes the head to increase in size. However it is
important to realise that hydrocephalus can also arise in older children and in adults.
Hydrocephalus is often classified as either communicating or
non-communicating. In the first type, the problem is usually failure to absorb the CSF at
the end of the system, whereas in the second there is blockage of the CSF pathways within
the ventricular system.
The usual treatment is to insert a shunting device. It is important to note that this
does not 'cure' the hydrocephalus and damage to the brain tissue that have occurred
remains. Shunting controls the pressure by draining excess CSF, so preventing the
condition becoming worse. Symptoms caused by raised pressure usually improve but other
problems of brain damage can remain.
Originally shunts were inserted so that a tube drained CSF from the ventricles in the
brain, through the valve and through another tube into a vein in the neck and then into
the heart (ventriculo-atrial or VA shunt). While these are still used, most nowadays drain
the CSF into the abdomen (ventriculo-peritoneal or VP shunt) and the bottom tube can be
felt over the ribs.
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Despite all the developments, shunting can have complications. These can be divided
into under-drainage, over-drainage and infection.
Under-drainage, in which the fluid is not
removed quickly enough and the symptoms of hydrocephalus return, is one of the commonest
problems. It is usually due to blockage of the upper or lower tubes of the shunt tissue,
though it can be due to the shunt breaking or its parts becoming disconnected from each
other. It is rarely due to the valve itself, which usually continues to function in the
same way for years.
In the case of over-drainage, the shunt
allows CSF to drain from the ventricles more quickly than it is produced. If this happens
suddenly, usually soon after the shunt is inserted, then the ventricles in the brain
collapse, tearing delicate blood vessels on the outside of the brain and causing a
haemorrhage ('subdural haematoma'). This can be trivial or it can cause symptoms similar
to those of a stroke. The blood may have to be removed, and in some cases if this is not
done it may be a cause of epilepsy later. If the overdrainage is more gradual, the
ventricles collapse gradually to become slit-like ('slit ventricles'). This often
interferes with shunt function causing the opposite problem, high CSF pressure, to
reappear, but unfortunately the slit ventricles do not always increase in size again,
producing the situation where there is very high CSF pressure with headache, vomiting etc
but very small ventricles on scan.
Infection is almost always due to
bacteria from the skin getting into the CSF or shunt at operation, and is remarkably
difficult to prevent. Antibiotics have not been shown to be of benefit for this purpose,
and other measures often have only a temporary effect, though obviously the care and
expertise of the surgical team is one of the most important factors in reducing the rate
of infection to a minimum. However, even in the best of hands infection still occurs.
Since the advent of shunting over forty years ago, the outcome for most children with
hydrocephalus is optimistic. Our pediatrician always likes to remember us one of his first
cases of a baby with hydrocephalus who received a shunt in Portugal. After going with some
complications when child (the shunt had broken and she needed to go to London, because
there wasn't a neurosurgeon in Portugal by that time that could solve the problem), she's
now a brilliant student.
However some children with hydrocephalus will have less than normal intelligence,
physical disabilities and a variety of other medical problems. Shunt malfunctions and
infections, developmental delays, learning disabilities and visual problems are not
uncommon. Families need to be aware of the life long complexities of hydrocephalus to
insure their children receive comprehensive on-going care and appropriate intervention
services and therapies.
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