What is Hydrocephalus?

Hydrocephalus is the abnormal buildup of cerebrospinal fluid in the ventricles of the brain. In most instances, hydrocephalus is a lifelong condition in that the patient is treated rather than “cured.” Presently, there is no known way to prevent or cure hydrocephalus and shunts are the primary method to treat hydrocephalus. The one-way calibrated shunt system was introduced in 1952.

Treatment by shunting the cerebrospinal fluid (CSF) to another area of the body, generally allows patients to lead full and active lives. There are different kinds and models of shunting systems. Although, shunts were a major medical breakthrough, there are problems that still remain unsolved in the treatment of hydrocephalus, such as shunt obstruction and infection.

An overwhelming majority of newborns with hydrocephalus will have a normal life span and normal or even superior intelligence. In addition, they will enjoy normal activities and be useful members of society. However, there are complications associated with hydrocephalus with learning disabilities being one of the most prevalent.

In most cases, hydrocephalus is not hereditary.

Types of Hydrocephalus

Hydrocephalus is a condition that can exist during one of two stages. It can be congenital, when the condition exists at birth or acquired, when it occurs as the result of a trauma to the brain after birth.

Forms of Hydrocephalus

Hydrocephalus exists in two forms; communicating (non-obstructive hydrocephalus) caused by inadequate absorption of CSF when the ventricular pathways are not obstructed; or noncommunicating (obstructive hydrocephalus) caused by blockage in the ventricular pathways through which CSF flows.

Hydrocephalus can also be either congenital, where the condition is present at birth or detected soon thereafter; or acquired, where the condition is acquired as the result of infection, head trauma, brain tumors, cysts, etc.

Ventricles of the Brain 

Cerebrospinal Fluid (CSF) is a clear, water-like fluid produced primarily within the lateral ventricles of the brain. In each ventricle, small flower-like tufts called choroid plexus produce CSF at a constant rate. The fluid flows through a discrete channel into the space around the brain and spinal cord, where it also functions as a cushion, and it is reabsorbed back into the blood stream. A small amount of CSF is also produced by the spinal cord. The CSF contains important chemicals and carries waste products away from tissues in and around the brain.

Hydrocephalus occurs when CSF accumulates as a result of a blockage in the circulation path or an overproduction.

The total volume of CSF is 125-150 ml. The normal resting pressure of the CSF is between 150-180 mm H2O. It has been calculated that 430 to 450 ml of CSF is produced daily.

Hydrocephalus Statistics

• In the United States, a little over 1 in 1000 births are affected by hydrocephalus.
• Hydrocephalus is one of the most common “birth defects” and afflicts in excess of 10,000 babies each year.
• Studies by the World Health Organization show that one birth in every 2,000 result in hydrocephalus.
• There are 70,000 discharges a year from hospitals in the United States with a diagnosis of hydrocephalus.
• More than 50% of hydrocephalus cases are congenital.
• As many as 75% of children with hydrocephalus will have some form of motor disability.
• Over the past 25 years, death rates associated with hydrocephalus have decreased from 54% to 5%; intellectual disabilitity has decreased from 62% to 30%.

Normal Pressure Hydrocephalus

• Shunted NPH has a success rate of 50%.
• In NPH, the success rate is best in patients with recent progression of mild dementia, gait disorder and urinary incontinence. Under those circumstances, 60% of the patients may improve, but a complication rate of 35% is not uncommon.

Figures Pertaining to Shunts

• There are 25,000 shunt operations performed each year in the United States. Of those, some 18,000 are initial shunt placements.
• Some 85% of people with shunts have had at least two shunt operations.
• Studies show that the risk of shunt failure in an infant’s first year is 30%.
• Shunts are revised about two times in the first ten years of use per patient.
• 95% of shunt infections occur within 3 to 5 days of surgery.
• The reported frequency of shunt infection varies from 1.5 to 39% with an average of 10 to 15%.
• The overall complication rate of CSF shunts remains quite high: 25 to 60%.
• More than 50% of staphylococcal infections occur with in 2 weeks of the operation, and 70% of infections occur within 2 months.
• Recent rates of infection range from 2% to 11% with infants less than 1 years of age having a higher incidence of infection.
• An average of 3 to revisions are usually required during childhood if treated for hydrocephalus from infancy.
• Ocular gaze and movement disorders are found in approximately 25 to 33% of children with hydrocephalus.
• These visits produce nearly 36,000 shunt-related procedures, 33,000 of which involve the placement of a shunt.
• CSF shunting procedures account for almost $100 million dollars of national health care expenditures in the United States.
• Nearly half of these dollars are spent on shunt revisions.
• Shunt malfunctions occur in about two to 40% of cases.
• Other medical conditions usually associated with Hydrocephalus:
  • About 80% of hydrocephalus patients are born with other defects.
  • Arachnoid Cysts.
  • Brain Injury.
  • Dandy-Walker Syndrome.
  • Head Trauma.
  • Meninigitis.
  • Porencephaly.
  • Tumors.
  • Spina Bifida.

• Hydrocephalus occurs in 70 to 90% of children with the most severe form of Spina Bifida.
• 90 to 95% of babies with spina bifida and related defects are born to parents with no family history of these disorders.

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