Hydrocephalus is an excessive accumulation of CSF, which manifests itself in the abnormal dilatation of spaces known as cerebral ventricles. This causes a damaging pressure on the brain , which is usually treated with a bypass system or catheter with a valve. However, the Neurosurgeon will indicate the best treatment in each case.
What is Hydrocephalus?
Hydrocephalus comes from the Greek roots in the term: "Hydro" (water) and "cephalus" (head). Following this definition, we could say that it is a condition whose main characteristic is the excessive accumulation of fluid in the brain. However, the "water" is actually Cerebrospinal Fluid (CSF), a clear liquid that surrounds the brain and spinal cord. Excessive accumulation of CSF is manifested in the abnormal dilatation of the cerebral spaces known as ventricles. This dilation causes a damaging pressure on the brain.
The ventricular system of the brain consists of four connected cerebral ventricles. Normally, CSF flows through them, leaves cisterns (enclosed spaces that serve as reservoirs) at the base of the brain, bathes the surface and spinal cord and then is reabsorbed into the bloodstream.
The CSF has three vital functions:1) Float the brain tissue , acting as a mattress or shock absorber.2) Serve as a vehicle to transport nutrients to the brain and eliminate waste.3) Flow between the skull and spine , to compensate for changes in the volume of blood within the brain.The balance between the production and absorption of CSF is of vital importance. Ideally, the fluid is almost completely absorbed into the bloodstream as it circulates. However, there are circumstances that prevent or alter CSF production, inhibiting its normal flow. At this moment in which the balance is disturbed appears Hydrocephalus.
Types of Hydrocephalus
Hydrocephalus may be congenital or acquired.- Congenital hydrocephalus : appears at birth and can be caused by environmental influences during the development of the fetus or by predisposition.- Acquired hydrocephalus : develops at birth or a point later.
On the other hand, Hydrocephalus can also be communicating or not communicating:- Hydrocephalus c omunicant : occurs when the CSF flow is blocked after exiting the ventricles. It is so named because the CSF can still flow between the ventricles, which remain open.- Non-communicating (or obstructive) hydrocephalus : occurs when CSF flow is blocked along one or more narrow pathways connecting the ventricles. One of the most common causes of hydrocephalus is the "aqueduct stenosis", a case resulting from a narrowing of the Silvio aqueduct, a small conduit between the third and fourth ventricles in the middle of the brain.
Hydrocephalus in adults
There are two more forms of hydrocephalus that do not fit into the categories described above, and which mainly affect adults:- Hydrocephalus ex vacuo : occurs when there is damage in the brain, caused by a stroke (stroke) or a traumatic injury. In these cases there may be a true contraction (atrophy or emaciation) of the brain tissue.- Normal pressure hydrocephalus (chronic hydrocephalus of the adult): occurs in elderly people and is characterized by many symptoms associated with other conditions that often occur in the elderly: memory loss, dementia, gait disorder, urinary incontinence and general reduction of daily life.
Hydrocephalus in infants
It is difficult to establish data on the incidence and prevalence of hydrocephalus, since there is no national registry of patients suffering from or diseases associated with the disease. However, it is believed that hydrocephalus affects one in 500 children. Currently, the majority of cases are prenatal diagnosis, at the time of birth or in early childhood. Also, the advances in technology of diagnostic images allow to detect it more accurately in people with atypical presentations.
How Hydrocephalus Occurs
Hydrocephalus may result from genetic inheritance (developmental disorders) or from developmental disorders, such as those associated with neural tube defects (including Spina Bifia and Encedalocele).Other possible causes are:- Complications of premature birth (ventricular hemorrhage, for example).- Diseases like meningitis.- Tumors.
- Cranial injuries or subarachnoid hemorrhage that blocks the ventricles out of the cisterns and eliminates the cisterns themselves.
Symptoms of Hydrocephalus
Symptoms vary with age, disease progression, and individual differences in CSF tolerance. A clear example is: a child does not have the same capacity as an adult to tolerate CSF pressure. A child's skull may expand to accommodate increased CSF because the sutures (fibrous joints connecting the skull bones) have not yet been closed.
In childhood, the obvious indication of hydrocephalus is the rapid increase in the circumference of the head or head size too large. Other symptoms may include: vomiting, sleepiness, irritability, downward deviation of the eyes and convulsions.
Older children and adults may experience different symptoms because their skull can not expand to accommodate increased CSF. Other symptoms may include: vomiting, papilledema (swelling of the optic disc part of the optic nerve), blurred vision, diplopia (double vision), downward deviation of the eyes, balance problems, poor coordination, walking disorder, incontinence urinary retention, reduction or loss of development, lethargy, drowsiness, irritability or other changes in personality and knowledge, including memory loss.
How Hydrocephalus Is Detected
Hydrocephalus is diagnosed with clinical neurological evaluation and cranial imaging techniques, such as:- Ultrasonography.- Computed Tomography (CT).- Magnetic resonance imaging (MRI).- Techniques for recording intracranial pressure.
The Neurosurgery expert will select the appropriate diagnostic tool based on age, clinical presentation and presence of known or suspected abnormalities of the brain or spinal cord.
How Hydrocephalus is treated
Hydrocephalus is treated by surgical placement of a bypass system. This system diverts the flow of CSF from the interior of the central nervous system to another part of the body where it can be absorbed as part of the circulatory process.
It is a flexible yet robust elastic tube. Thus, it consists of a tube , a catheter and a valve. One end of the catheter is inserted into the central nervous system (inside the ventricle inside the brain or inside a cyst or inside the spinal cord). The other end of the catheter is normally placed inside the abdominal cavity , but it can also be placed in other parts of the body, such as in a heart chamber or in a pulmonary cavity where the CSF can drain and be absorbed. The valve located along the catheter maintains the flow in one direction and regulates the amount of CSF flow .
On the other hand, a limited number of patients can be treated with a different procedure, called a ventriculostomy. In this way a neuroendoscope (a small camera designed to visualize small surgical areas and difficult to access) allows the doctor to see the ventricular surface. The neuroendoscope is guided so that a small hole can be made in the third ventricle, allowing the CSF to pass the obstruction and flow to the resorption site around the surface of the brain.