Understanding 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 of the brain (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 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. Due to the enlargement of the ventricles the pressure on the brain (intracranial pressure) rises which can lead to serious neurological damages of 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 (Circulation of CSF 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 do have an abnormal head circumference. Congenical hydrocephalus can occur together with diseases like:

• Spina Bifida 
• Dandy-Walker syndrome
• Aquaduct Stenosis

Acquired hydrocephalus can occur at any stage in human lifetime as a consequence of an accident, surgery, cerebral bleeding, tumor, meningitis and/or others. A special form of acquired hydrocephalus is the so called Normal Pressure Hydrocephalus (NPH). Normal pressure hydrocephalus describes a neurologic condition of ventricular dilatation in the absence of increased CSF pressure. NPH is characterized 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 tumor. NPH is a disease of the elderly population, with an increasing incidence beginning between the ages of 65 and 70 years.

Symptoms

The symptoms of hydrocephalus vary with the age of the patient furthermore other diseases may influence those symptoms.

Treatment

Depending on patients age and symptoms, there are different options to diagnose hydrocephalus. A diagnose normally always consist of 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 a non-communicating hydrocephalus, an endoscopic procedure (endoscopic third ventriculostomy (ETV)) often is the treatment of choice. Through a small opening in the head, the surgeon is using 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 a shunt system allowing the excessive 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 consist 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. Nevertheless it might be necessary to see the surgeon for regular check-up’s to adapt the valve pressure. Furthermore frequently consultations gives the chances to detect potential complications. As every surgery also a shunt surgery contains the risk of a complication. When new symptoms occurs you should visit your physician.