Understanding hydrocephalus

The following sections provide helpful information about hydrocephalus

What is hydrocephalus?

Hydrocephalus is also known as “water on the brain”. It is caused by an abnormal accumulation of cerebrospinal fluid (CSF) in the inner ventricles of the brain. The ventricular system consist of four ventricles connected by narrow passages. CSF flows through the ventricles before it exits into a cavity, the so called the subarachnoid space.

CSF covers the brain and the spinal cord and usually reabsorbs into the bloodstream, thus production and absorption is normally balanced. CFS has, amongst others, the following important life-sustaining functions:

• To act as a cushion or "shock absorber“ against injuries
• To deliver nutrients and proteins that are needed for the nourishment and normal function of the brain

An imbalance in production and absorption results in an abnormal widening of the ventricles. The enlargement of the ventricles increases the pressure on the brain (intracranial pressure), which can lead to serious neurological damage to the brain. In some cases the cause of hydrocephalus are not clearly identifiable.

Types

Hydrocephalus can be classified as:

Communicating (CSF circulation, via the ventricles of the brain, is intact, but the absorption into the venous bloodflow is blocked) and Non-communicating or obstructive (CSF Circulation  is blocked somewhere between the lateral, third and/or fourth ventricles.)

Other classifications are:

Congenital hydrocephalus is present at birth. Children born with hydrocephalus may be diagnosed during the pregnancy or at birth. Often children born with hydrocephalus have an abnormal head circumference. Congenital hydrocephalus can occur together with diseases like:

• Spina Bifida 
• Dandy-Walker syndrome
• Aquaduct Stenosis

Acquired hydrocephalus can occur at any stage of life as a consequence of an accident, surgery, cerebral bleeding, tumour, meningitis or other causes. A special form of acquired hydrocephalus is the so called Normal Pressure Hydrocephalus (NPH). Normal pressure hydrocephalus describes a neurologic condition of ventricular dilation in the absence of increased CSF pressure. NPH is characterised by a triad of gait impairment (a broad-based, shuffling, magnetic gait), urinary incontinence and a form of dementia.

The importance of this diagnosis lies in the fact that it is a potentially reversible cause of dementia. The cause of NPH is often unclear. These cases are called “primary” or “idiopathic” NPH (iNPH). The remaining cases are so called secondary NPH (sNPH). The cause of the disease known and secondary to either a head injury, subarachnoid bleeding, meningitis or a tumour. NPH is a disease of the elderly population, with an increasing incidence beginning between the ages of 65 and 70 years.¹

Symptoms

The symptoms of hydrocephalus vary with the age of the patient, and other diseases may infuence the symptoms.

Treatment

Depending on patients age and symptoms, there are different options to diagnose hydrocephalus. A Diagnosis generally utilises imaging techniques like ultrasonography, computed tomography (CT) or magnetic resonance tomography (MRT). With the help of the imaging techniques, shape and size of the ventricles become visible.

Endoscopic procedure

In the event of non-communicating hydrocephalus, an endoscopic third ventriculostomy (ETV) procedure is often the treatment of choice. (endoscopic third ventriculostomy (ETV)) often is the treatment of choice. Through a small opening in the head, the surgeon uses an endoscope to either remove the blockage or to open the ventricles, allowing the CSF to circulate again.

Shunt surgery

The most common procedure is to implant shunt system, allowing the excess CSF to flow through a thin silicone tube from the brain into another part of the body, usually the abdomen. From here the fluid is absorbed into the blood stream. The shunt consists of a catheter and a valve to control the flow of CSF and to ensure a normal brain pressure. Shunt surgery is carried out by an experienced neurosurgeon. Patients will be given a general anaesthetic before the operation, which usually takes less than an hour.

After surgery

A high quality hydrocephalus shunt is designed to stay implanted for a lifetime, however it might be necessary to see the surgeon for regular check-up’s to adapt the valve pressure. Frequent consultations give the chance to detect potential complications. As with numerous surgeries, shunt surgery carries risks of complications, therefore patients should inform their consultant if new symptoms occur.