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UNDERSTANDING HYDOCEPHALUS Text
extracted from the "Guide to Hydrocephalus" available
at our association Hydrocephalus is derived from the Greek words hydro, meaning water, and cephalus, meaning head. As the name implies, hydrocephalus is a condition which exists when there is excess fluid in the head. This is not to say that only people with hydrocephalus have water in their head. Everyone has a certain amount of fluid, called cerebrospinal fluid (CSF), located within four ventricles or spaces that are present in the brain. Choose one of the following title to have more information:
Normally, cerebrospinal fluid is produced in the lateral ventricles by a specialized tissue called the Choroid Plexus. It flows out of these ventricles through a passage called the Foramen of Monroe and into the third ventricle. From here the fluid passes through the Aqueduct of Sylvius into the fourth ventricle. The CSF leaves the fourth ventricle by passing through three foramens or openings into the subarachnoid space which surrounds both the brain and the spinal cord. Once in the subarachnoid space, most of the CSF is absorbed at the top and midline of the brain through specialized cell clusters (arachnoid villi) that pass the fluid into a large vein called the sagittal sinus. It is here that the CSF enters into and mixes with the blood stream. The CSF that passes along the outside of the spinal cord is ultimately absorbed by the lymph system. This is also the fate of a small amount of CSF that passes directly into and through the brain itself. The system of fluid production and reabsorption operates continually and a certain amount of internal pressure exists within the ventricles. This is both normal and healthy.
A number of circumstances can arise wherein the pressure that exists within the ventricles becomes higher than normal. Should this occur and the ventricles become enlarged, the condition known as hydrocephalus exists. As the ventricles expand, pressure is placed on the brain itself, sometimes compressing it against the skull. In infants and toddlers, this may result in an enlargement of the head. Once the skull has completely hardened, other acute effects may occur. The types of hydrocephalus are separated into two main categories:
Hydrocephalus may develop in the womb or after birth as a result of a congenital defect. Congenital defects are not necessarily hereditary but are the result of something that goes wrong during the development of the fetus. This includes the condition known as spina bifida. It may also result from complications associated with premature birth or it may develop at some later time in one's life as a result of haemorrhaging, trauma, tumour growth, meningitis or other factors. When hydrocephalus occurs after birth it is called acquired hydrocephalus.
Among the acquired hydrocephalus, one of the forms can appear to people of more than 60 years old: the normal pressure hydrocephalus (NPH). It causes a widening of ventricles cerebral without notable increase in the intracranial pressure. The principal symptoms of HPN are walking difficulties, psychic disorders and urinary incontinence. Derivation is, as for the other forms of hydrocephalus, the most common treatment for NPH.
The treatment of hydrocephalus usually involves surgically implanting a "shunt" which removes excess fluid from the brain and takes it to another region of the body. Most shunts that are installed today are drained into the abdominal cavity (peritoneal cavity) where the stomach and intestines are located. Here the CSF is reabsorbed into the body. These shunts are called ventriculoperitoneal (V-P) shunts. A shunt is usually made up of three parts:
In most cases, a shunt is the only viable treatment option. If a tumour is present, it may be possible to remove it, thereby restoring the normal flow of CSF. A surgical procedure is occasionally tried which creates an opening between the third ventricle and the subarachnoid space, thus bypassing an obstruction in the Aqueduct of Sylvius. This procedure is only 50% successful and usually leaves the child with some enlarged ventricles. Medicines are not usually effective.
Are there any problems with shunts?
How does one treat a malfunctioning shunt?
What are the symptoms of hydrocephalus and shunt failure?
Symptoms of Hydrocephalus/Shunt Malfunction
* Specific to shunt malfunction only
What are the consequences of hydrocephalus? The high pressures experienced by the brain before a shunt is installed can result in lasting effects, both short and long term. These are summarized below. It is important to note that the condition of hydrocephalus differs substantially from individual to individual in terms of the cause, areas of the brain directly affected, treatment variables (such as age at diagnosis, type and location of the shunt, medications) and associated complications (such as infections, bleeding, seizures). As a result, each case will be very individual in nature.
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