Hydrocephalus

Clinical picture

Hydrocephalus refers to a condition whereby the volume of the "water" (hydro) in the "head" (cephalus) continually increases.

Normally the production and resorption of cerebrospinal fluid (CSF) are balanced. Healthy adults produce approximately 500ml of the cerebrospinal fluid daily, whereas small children produce about 250ml per day and infants about 100ml per day. Hydrocephalus patients suffer from a disturbed balance between resorption and production of CSF. If the amount of CSF that is produced exceeds the amount that is resorbed, the ventricles will expand.

Medical science distinguishes between congenital hydrocephalus (hydrocephalus is present before birth) and acquired hydrocephalus (the disease develops later in life).

A further distinction is made between: 

Hydrocephalus occlusus

= non communicating hydrocephalus:
In hydrocephalus occlusus, the channels between the ventricles are severed in such a way that they are unable to "communicate" with each other. 

Hydrocephalus communicans

= communicating hydrocephalus:
Cases in which the channels between the ventricles are unobstructed but resorption of cerebrospinal fluid is impaired are defined as hydrocephalus communicans.

Anatomy of the brain

Brain

 

 

1 scullcap

2 brain

3 lateral ventricle

4 third ventricle

5 cerebrospinal fluid (CSF)

6 fourth ventricle

Ventricular system

Inside the head a fluid called cerebrospinal fluid (CSF) surrounds the brain and fills the space known as the ventricular system. Essentially, the brain and the spinal cord "float" in the CSF, which acts like a buffer for the cortex and protects the brain from physical injuries.

The choroid plexus, a vascularised structure that is located in the lateral brain ventricles, produces CSF about a rate of 500 ml/day. The CSF circulates from the lateral ventricles into the third ventricle, then by passing the cerebral aqueduct, to the fourth ventricle and into the subarachnoid space. The CSF finally flows to the spinal cord.

The CSF has many different functions: the mechanical protection of the brain, the regulation of the intracranial pressure, keeping the brain tissue moist and finally the distribution of metabolites. The absorption of cerebrospinal fluid occurs in the arachnoid villi. The arachnoid membrane permits the uni-directional flow of CSF out into the venous blood.