Hydrocephalus is a neurological condition that occurs when there is an abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles or subarachnoid space of the brain.  It is commonly known as ‘water on the brain”  Hydrocephalus is termed “congenital” when it exists at birth, or “acquired” when it occurs as the result of injury to the brain after birth (examples are infection such as menagitis, intraventricular hemorrhages or tumors). 

The Importance Of Cerebrospinal Fluid

The head contains three main components: brain tissue, blood vessels, and clear liquid similar to salt water. This clear cerebrospinal fluid (CSF) makes up about 10% of the volume within the skull and has two main purposes. First, it cushions the delicate brain and spinal cord tissues from injury. Secondly, it maintains the proper balance of protein, sugar and salts to nourish these central nervous system tissues. Cerebrospinal fluid is continuously made (approximately .3 cc per minute) in the ventricles. The ventricles are four connecting cavities deep within the brain which provide a pathway through which CSF circulates. At the back of the head, the CSF passes out of the brain and then over the surface of the brain and spinal cord and finally returns to the blood system through absorbing structures in the lining surrounding the brain. Under normal conditions, almost all this fluid is absorbed into the bloodstream, thus maintaining the delicate balance between production and absorption of CSF. When this system becomes unbalanced, almost always due to obstruction in the circulation pathways or malfunction of the CSF absorbers, production of CSF continues, excess fluid builds up in the brain and the condition known as hydrocephalus occurs.

 Here is basic picture of the brain.  The main focus in the picture is of the ventricles.  The ventricular system of the brain is made up of four chambers which are all connected to each other by narrow passages, called foramen.  Hydrocepahlus occurs when there is an obstruction of one of the ventricles or the ventricular formania (csf passageways) that restricts the flow of CSF within the ventricular system, subarachnoid space, or the cisterns (reservoirs for CSF). 

Types Of Hydrocephalus

Neurosurgeons classify hydrocephalus according to when the condition was developed (congenital or acquired), and whether it was caused by a reabsorption problem or a blockage somewhere within the ventricles (communicating or non-communicating). 

Congenital Hydrosephalus

Congenital hydrocephalus is typically traced back to a birth defect or brain malformation that causes an increase resistance to the drainage of csf.  Some neurological conditions and congenital malformations that are often associated with hydrocephalus are Dandy-Walker Syndrome, Neural Tube Defects, Spina Bifida, Chiari Malformations, Vein of Galen Malformations, Hydranencephaly, Craniosynostosis, and Schizencephaly.

Acquired Hydrocephalus

Acquired hydrocephalus is acquired later in life if something causes an increase in the resistance in the drainage of CSF, such as an obstruction.  Acquired hydrocephalus can be caused by arachnoid cysts, intraventricular hemorrhaging (IVH), trauma to the head, infection such as meningitis, or a brain tumor.

For greater detail of what hydrocephalus is and the conditions associated with it.  I found a wonderful reference book which will go into detail about each condition and more so.  Look for the book called HYROCEPHALUS A Guide for Patients, Families & Friends.   The is a wonderful book and has been so useful since Madison was born and diagnosed with Hydrocephalus