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Normal pressure hydrocephalus (NPH)

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Normal pressure hydrocephalus (NPH)

Definition:

Normal pressure hydrocephalus (NPH) is a brain disorder that occurs when the flow of cerebrospinal fluid is blocked. The fluid fills up within the brain, which in turn compresses brain tissue. The person may lose any or all brain functions controlled by the area of the brain that is compressed.

Alternative Names:
Hydrocephalus - idiopathic; Hydrocephalus - adult; Hydrocephalus - communicating, "water on the brain"

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Causes, incidence, and risk factors:

Normal pressure hydrocephalus (NPH) can be a reversible or treatable disorder. It is thought to account for about 5% of all dementias. The symptoms often begin gradually.

NPH is a form of hydrocephalus, also known as "water on the brain", which means there is too much fluid compressing the brain. It can occur without identifiable cause, or it may be caused by any condition where the flow of cerebrospinal fluid (CSF) is blocked. The CSF is produced in normal amounts in this condition, but it is prevented from being normally re-absorbed.

The ventricles (fluid-filled chambers) of the brain enlarge to accommodate the increased volume of CSF so the pressure of CSF, when measured by lumbar puncture (spinal tap), remains normal. Brain tissue is damaged or destroyed because of compression by the fluid-filled ventricles. If there is an identifiable cause and the cause can be corrected, the symptoms may reverse or at least stop getting worse. If there is no identifiable cause, the disorder is often progressive.

Risk factors include disorders that may cause obstruction of the flow of CSF, such as closed head injury, surgery on the brain (craniotomy), meningitis or similar infections, and subarachnoid hemorrhage (bleeding from a blood vessel or aneurysm in the brain).

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