Overview

Hydrocephalus is a condition in which excess cerebrospinal fluid (CSF) builds up within the ventricles (fluid-containing cavaties) of the brain. Under normal conditions, CSF circulates through the brain, its ventricles and the spinal cord acting as a protective cushion for the delicate brain and spinal cord tissue from injuries and a provider of nutrients.

The average adult produces about 500mls of CSF daily. When an injury or illness alters the circulation of CSF, one or more of the ventricles becomes enlarged as CSF accumulates. In adults, the skull is rigid and cannot expand, so the pressure in the brain may increase profoundly. If left untreated, hydrocephalus will create increased pressure in the head and may result in brain damage or even death.

What are the different types of Hydrocephalus?

1. Communicating (Non-obstructive)

• Due to a blockage outside the ventricular system or anabsorption problem
• E.g. Bleeding, infection, trauma, tumours, unknown causes

2. Non-communicating (Obstructive)

• Due to a blockage within the ventricular system
• E.g. Bleeding or tumour outside the ventricles, congenital

Hydrocephalus can be acute (fast onset of symptoms) or chronic (symptoms are slow in onset and more insidious). It can be active (with the patient quickly deteriorating), compensated (to some extent) or arrested. In most cases, the pressure of the CSF within the ventricles is high. However in some instances (e.g. Normal Pressure Hydrocephalus), the pressure of the CSF may be normal.

Causes

A number of conditions can lead to hydrocephalus. It may result from inherited genetic abnormalities (such as the genetic defect that causes aqueductal stenosis) or developmental disorders (such as those associated with neural tube defects including spina bifida).

Other possible causes include complications of premature birth such as intraventricular haemorrhage, diseases such as meningitis, tumours, traumatic head injury which block the exit of CSF from the ventricles to the cisterns or eliminate the passageway for CSF into the cisterns.

Symptoms

Acute hydrocephalus

• Drowsiness and altered consciousness
• Headache
• Nausea and vomiting
• Unsteadiness

Subacute or low-pressure hydrocephalus

• As above symptoms, but slower in onset and more insidious

Normal pressure hydrocephalus (NPH)

• Gait disturbances (Difficulty walking)
• Dementia or forgetfulness
• Bladder control problems

Risk Factors

Hydrocephalus can occur at any age, but is most common in infants and adults age 60 and older. It can affect adult males and females after an injury or illness, as well as people of different races equally.

When to Seek Help

Adults, especially those above 60 years, with walking difficulties that cannot be attributed to injury or arthritis should undergo a complete health screening and neurological examination.

Diagnosis

How is Hydrocephalus diagnosed?

Radiologically, hydrocephalus usually presents with dilated or big ventricles as seen in CT scan or MRI. If a person exhibits symptoms of hydrocephalus, other tests that may be performed include:

1. Isotopic cisternography
   A test that involves injecting a radioactive isotope into the lower back through a spinal tap. This allows the absorption of CSF to be monitored over a period of time (up to 4 days).
2. Lumbar puncture (spinal tap)
   Under local anaesthesia, a thin needle is passed into the spinal fluid space of the lower back. Removal of 50cc of CSF is done to see if symptoms are temporarily relieved. This test is used to measure CSF pressure and analyze the fluid. This procedure may help determine whether a shunt will work. If lumbar puncture improves the symptoms even temporarily, this can be an indication that a shunt will be successful. However, there have been patients who showed no improvement but went on to have a successful shunt procedure.
3. Intracranial pressure monitoring
   Monitoring may be able to detect an abnormal pressure or pattern of pressure waves. Monitoring requires insertion of a catheter or small fiber optic cable through the skull into the brain. This procedure requires admission to the hospital for 24 hours.

Sometimes, the diagnosis of NPH can be difficult because the symptoms are also associated with illnesses like Alzheimer’s and Parkinson’s diseases as well as with the normal ageing process.

Treatment Options

How is Hydrocephalus treated?

Hydrocephalus cannot be cured, but can be control in a variety of ways. The problem area may be treated directly (by removing the cause of CSF obstruction, e.g. tumour), or indirectly (by diverting the fluid to somewhere else). Sometimes, if the pressure in the brain is high, and/or the CSF is mixed with blood (e.g. after a bleeding in the brain), a temporary drain - External Ventricular Drainage (EVD) system may be inserted to relieve the increased pressure build up inside the brain. Alternatively when the brain is clear of blood, a permanent shunt will be inserted.

Permanent shunt

The most common method of treatment of hydrocephalus is a surgical placement of a shunt. A shunt is a flexible tube placed into the ventricular system that diverts the flow of CSF into another region of the body where it can be absorbed. The CSF is diverted via a tube tunnelled under the skin; a valve in the tubing system regulates the flow of the CSF.

This regulation occurs either through different pressure ranges or different flow rates (i.e. pressure-regulated or flow-regulated). A ventriculoperitoneal (VP) shunt is the most common of all shunts with the distal end of the shunt being inserted into the peritoneal (abdominal) cavity. Other shunts include: a ventriculoatrial (VA) shunt draining into the heart, a ventriculopleural shunt draining into the lung lining and a lumboperitoneal shunt which actually drains CSF from the spinal canal into the peritoneal cavity.

There are many different shunts available in the market. While no valve has proven conclusively to be superior over the other, some patients would benefit from special valves such as the programmable valves (where the pressure setting can be altered). Most doctors would select valves of a particular design and pressure setting based on experience and the patient’s condition. The most common valve used, however, is the medium pressure valve.

What is the prognosis for Hydrocephalus?

The prognosis for hydrocephalus depends on the cause, the extent of symptoms, and the timeliness of diagnosis and treatment. In general, the earlier hydrocephalus is diagnosed, the better the chance for successful treatment. The longer the symptoms have been present, the less likely it is that treatment will be successful. Some patients show a dramatic improvement with treatment while others do not. In some instances of NPH, dementia can be reversed by shunt placement. Other symptoms such as headaches may disappear almost immediately if the symptoms are related to elevated pressure. Recovery may be limited by the extent of the damage already caused by the hydrocephalus and by the brain’s ability to heal.

What are the complications and risks involved with Shunting?

As with any surgery, there are risks involved. The most common complication of shunting is obstruction of the system that may occur at any point along the course of the shunt. Another common complication of shunt surgery is shunt malfunction, which can occur when either end of the shunt is malpositioned, the valve fails to function properly or the CSF is not efficiently reabsorbed. Additional complications include an infection involving the surgical wound, the shunt or the CSF; bleeding into the brain or ventricles; or a seizure. Fortunately, these complications are uncommon and can be managed successfully in almost all cases; although treatment may require additional surgery.

Important symptoms to look out for:

• Difficulty in waking up or staying awake
• Fever
• Headache
• Irritability and/or tiredness
• Loss of coordination or balance
• Nausea and/or vomiting
• Personality changes
• Vision problems
• Seizures
• Swelling or redness along the shunt track

If any of the above symptoms occur, please seek medical attention immediately.

Follow-up

Shunts are expected to perform reliably over a long period of time. However, because hydrocephalus is an ongoing condition, patients do require long-term follow-up care by a doctor.

Precautions

Generally, patients with an implanted shunt system are not restricted in their daily activities, except those involving great physical exertion. If you are not sure, please discuss with your doctor in advance.