Overview of Normal Pressure Hydrocephalus (NPH)

Normal pressure hydrocephalus (NPH) is a condition that involves the build-up of fluid in the brain. Normally, a fluid called cerebrospinal fluid (CSF) circulates around the brain and spinal cord. This fluid cushions, cleanses, and brings nutrients to the cells in the brain and spine. CSF is produced in small, hollow spaces within the brain called ventricles. For people in good health, excess CSF normally drains away into the bloodstream as fresh CSF is produced.

When cerebrospinal fluid does not drain properly, the cerebrospinal fluid builds up in the ventricles and NPH can occur. This build up puts pressure on the brain, interfering with healthy brain function. NPH most commonly affects the areas of the brain that control leg movement, bladder function, and cognitive abilities such as problem solving, speaking, and remembering.

"Hydrocephalus" was once called "water on the brain," but we now know that the water is CSF. The term "normal pressure" refers to the fact that this type of hydrocephalus, which generally develops slowly, has a lower CSF-pressure than other types of hydrocephalus. Normal pressure hydrocephalus occurs mainly in people over the age of 60 and symptoms may be mistaken for other disorders, such as Parkinson's disease, Alzheimer's disease, dementia, or Creutzfeldt-Jakob disease. However, with proper diagnosis and treatment many of the symptoms of NPH can be controlled or greatly reduced. In some cases, a nearly complete recovery is possible.

Incidence and Prevalence of Normal Pressure Hydrocephalus

There are no definitive statistics for the prevalence of NPH in the United States at this time. Some experts estimate that up to 750,000 Americans may have NPH. Estimates also suggest that NPH may be the cause for up to 5% of dementia cases. NPH occurs at about the same rate in men and women and there is no correlation between NPH and race. In general, NPH usually affects patients over the age of 50, with most patients being age 60 or older.

Publication Review By: Alan B. Ettinger, M.D.

Published: 06 May 2006

Last Modified: 28 Sep 2015