Hydrocephalus

What is Hydrocephalus?
Statistics on Hydrocephalus
Risk Factors for Hydrocephalus
Progression of Hydrocephalus
How is Hydrocephalus Diagnosed?
Prognosis of Hydrocephalus
How is Hydrocephalus Treated?
Hydrocephalus References

What is Hydrocephalus?

Hydrocephalus can be defined as increased volume of cerebrospinal fluid (CSF) within the brain. This may be due to:1) Too much CSF produced2) An obstruction of CSF flow 3) Problem with absorption of CSF The increased volume of CSF results in increased pressure within the brain (intracranial pressure) which may cause damage to the delicate brain tissue and resultant neurological effects such as drowsiness and seizures.

Statistics on Hydrocephalus

The incidence of congenital hydrocephalus is approximately 3 for every 1000 live births.The incidence of adult hydrocephalus depends on the frequency of precipitating causes, such as brain infections and so forth. Hydrocephalus is estimated to affect 1 in every 10,000 people at some point in their lifetime. The incidence in males and females is roughly equal. Peak incidence occurs in infancy and adulthood.

Risk Factors for Hydrocephalus

In one third of all cases of hydrocephalus the cause is unknown.

Masses such as brain tumours, cysts, abscesses or blood clots may obstruct the flow of CSF.

Prior brain surgery may cause hydrocephalus by blocking normal pathways of CSF flow.

Subarachnoid haemorrhage.

Head injury.

Bacterial meningitis (particularly tuberculosis)

Progression of Hydrocephalus

Depending on the time frame involved, hydrocephalus may be acute, subacute or chronic in nature.Hydrocephalus can be classified according to the cause of the increased volume of CSF.

Communicating hydrocephalus occurs when there is no obstruction of flow of CSF through the ventricles to the subarachnoid space so hydrocephalus is the result of defective absoprtion of CSF and/or or increased production (rare).

Noncommunicating hydrocephalus occurs when there is obstruction to CSF outflow. Obstruction may be caused by a variety of things including mass lesions such as tumours or cysts.

Normal pressure hydrocephalus is a rare syndrome where elderly patients have enlarged ventricles, normal CSF pressure and no cortical atrophy.

Infantile hydrocephalus causes include benign extrenal hydrocephalus, Arnold-Chiari malformation, Dandy-Walker syndrome, stenosis of the aqueduct of Sylvius, congenital toxoplasmosis and following a subarachnoid haemorrhage or meningitis.

If hydrocephalus remains untreated the intracranial pressure will rise eventually resulting in compression of the brain stem and subsequently death from respiratory causes.

How is Hydrocephalus Diagnosed?

A CT and/or MRI scan can assess the dilatation of the ventricles and look for other structures in the brain.

Lumbar puncture: If the hydrocephlus is suspected to be due to a bleed inside the brain or following an episode of meningitis. CSF will show red blood cells in a subarachnoid haemorrhage and may reveal any infection present. Lumbar puncture should only be done after a CT/MRI has been done.

An ultrasound of the brain through the anterior fontanelle can be done in infants.

Prognosis of Hydrocephalus

The prognosis is dependent on the underlying cause. The outlook is particularly poor for untreated hydrocephalus in infants; these often result in infection and death. A small number will survive to childhood, but have some degree of intellectual handicap and developmental issues. The outlook is good for infants with treated non-tumour related hydrocephalus - 70% will maintain a normal IQ and attend normal school. Damage already sustained tends to be permanent - loss of cognitive function may pesist even after treatment as may visual loss.

How is Hydrocephalus Treated?

Medical therapy using various medications can be used to buy time until surgery however, surgery is the preferred treatment. The majority of patients with hydrocephalus end up having a shunt which will drain CSF into either the abdomen or the heart depending on the type of shunt used.

Hydrocephalus References

Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison's Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.Emedicine. Hydrocephalus excerpt, 2004Hankey G., Wardlaw J. Clinical Neurology. Demos Medical Publishing, United Kingdom, 2002. Haslet C, Chiliers ER, Boon NA, Colledge NR. Principles and Practice of Medicine. Churchill Livingstone 2002.Hurst JW (Editor-in-chief). Medicine for the practicing physician. 4th edition Appleton and Lange 1996.Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders 2002 Pg 427-430.Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford Universtiy Press. 2001McLatchie G and LEaper DJ (editors). Oxford Handbook of Clinical Surgery 2nd Edition. Oxford University Press 2002.Raftery AT Churchill's pocketbook of Surgery. Churchill Livingsone 2001.