Hydrocephalus is an excessive accumulation of Cerebrospinal Fluid (CSF), which manifests itself in the abnormal dilation of spaces known as brain ventricles. This causes detrimental pressure in the brain, which is usually treated with a shunt 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 fluid that surrounds the brain and spinal cord. Excessive accumulation of CSF manifests itself in the abnormal dilation of the brain spaces known as ventricles. This dilation causes harmful pressure in the brain.
The ventricular system of the brain consists of four connected cerebral ventricles. Normally, CSF flows through them, exits into cisterns (closed spaces that serve as reservoirs) at the base of the brain, bathes the surface and spinal cord, and is then reabsorbed into the bloodstream.
CSF has three vital functions:
1) To keep brain tissue buoyant, acting as a cushion or shock absorber.
2) To serve as a vehicle for transporting nutrients to the brain and eliminating waste.
3) To flow between the skull and the spinal column, to compensate for changes in blood volume within the brain.
The balance between CSF production and absorption is of vital importance. Under ideal conditions, the fluid is almost completely absorbed into the bloodstream as it circulates. However, there are circumstances that prevent or alter the production of CSF, inhibiting its normal flow. At this moment when the balance is disturbed, Hydrocephalus appears.
What are the types of Hydrocephalus?
Hydrocephalus can be congenital or acquired.
– Congenital hydrocephalus: appears at birth and can be caused by environmental influences during fetal development or by predisposition.
– Acquired hydrocephalus: develops at birth or at a later stage.
On the other hand, Hydrocephalus can also be communicating or non-communicating:
– Communicating hydrocephalus: occurs when CSF flow is blocked after exiting the ventricles. It is so called because CSF can still flow between the ventricles, which remain open.
– Non-communicating (or obstructive) hydrocephalus: occurs when the flow of CSF is blocked along one or more narrowed pathways connecting the ventricles. One of the most common causes of hydrocephalus is “aqueductal stenosis”, a case resulting from a narrowing of the aqueduct of Sylvius, a small duct between the third and fourth ventricles in the middle of the brain.
- Hydrocephalus in adults
There are two other forms of hydrocephalus that do not fit into the categories described above, and affect mainly adults:
– Hydrocephalus ex vacuo: occurs when there is damage to the brain, caused by a stroke (ictus) or traumatic injury. In these cases there may be a true shrinkage (atrophy or emaciation) of the brain tissue.
– Normal pressure hydrocephalus (chronic adult hydrocephalus): occurs in the elderly and is characterized by many symptoms associated with other conditions that often occur in the elderly: memory loss, dementia, gait disturbance, urinary incontinence and general reduction of daily life.
- Hydrocephalus in infants
It is difficult to establish data on incidence and prevalence of hydrocephalus, as there is no national registry of patients with hydrocephalus or associated disorders. However, it is believed that hydrocephalus affects one in 500 infants. Currently, most cases are diagnosed prenatally, at birth or in early childhood. Also, advances in diagnostic imaging technology allow for more accurate detection in individuals with atypical presentations.
How does Hydrocephalus occur?
Hydrocephalus may result from genetic inheritance (aqueductal stenosis) or developmental disorders, such as those associated with neural tube defects (including Spina Bifida and Encedalocele).
Other possible causes are:
– Complications of premature birth (ventricular hemorrhage, for example).
– Diseases such as meningitis.
– Tumors.
– Cranial trauma or subarachnoid hemorrhage that blocks the ventricles’ exit to the cisterns and eliminates the cisterns themselves.
Existing 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 ability as an adult to tolerate CSF pressure. A child’s skull may expand to accommodate the increased CSF because the sutures (fibrous joints connecting the bones of the skull) have not yet closed.
In infancy, the obvious indication of hydrocephalus is rapid increase in head circumference or an overly large head size. Other symptoms may include vomiting, sleepiness, irritability, downward deviation of the eyes, and seizures.
Older children and adults may experience different symptoms because their skull cannot expand to accommodate the increased CSF. Thus, 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, gait disturbance, urinary incontinence, reduction or loss of development, lethargy, drowsiness, irritability, or other changes in personality and cognition, including memory loss.
Tests to diagnose Hydrocephalus
Hydrocephalus is diagnosed with clinical neurological evaluation and cranial imaging techniques, such as:
– Ultrasonography.
– Computed tomography (CT).
– Magnetic resonance imaging (MRI).
– Intracranial pressure recording techniques.
The Neurosurgery expert will select the appropriate diagnostic tool based on age, clinical presentation and the presence of known or suspected abnormalities of the brain or spinal cord.
What is the best treatment for Hydrocephalus?
Hydrocephalus is treated by surgical placement of a shunt system. This system diverts the flow of CSF from within the central nervous system to another area of the body where it can be absorbed as part of the circulatory process.
It is a flexible but 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 (into the ventricle inside the brain or into a cyst or into the spinal cord). The other end of the catheter is placed inside the abdominal cavity, usually, but may also be placed in other parts of the body, such as in a heart chamber or in a lung cavity where CSF can drain and be absorbed. The valve 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 ventriculostomy. In this way a neuroendoscope (a small camera designed to visualize small, hard-to-reach surgical areas) allows the physician to view the ventricular surface. The neuroendoscope is guided so that a small hole can be made in the third ventricle, allowing CSF to pass the obstruction and flow to the reabsorption site around the surface of the brain.