Normal pressure hydrocephalus (NPH)
Key points
- Normal pressure hydrocephalus (NPH) is a brain disorder caused by blockage of the flow of cerebrospinal fluid, with enlargement of the ventricles within the brain and compression of the brain tissue.
- Normal pressure hydrocephalus (NPH) can be a reversible or treatable disorder.
- Signs and tests An examination shows gait changes related to the damage within the brain.
- Symptoms progress and the disorder results in death.
Alternative names
Hydrocephalus - idiopathic; Hydrocephalus - adult; Hydrocephalus - communicating, "water on the brain"
Definition
Normal pressure hydrocephalus (NPH) is a brain disorder caused by blockage of the flow of cerebrospinal fluid, with enlargement of the ventricles within the brain and compression of the brain tissue.
It may result in loss of any or all brain functions controlled by the area of the brain which is compressed.
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 incidence is 1 out of 100,000 people. NPH can occur at any age. The onset of symptoms is often gradual.
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 there is an obstruction to the flow of cerebrospinal fluid (CSF). 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).
Symptoms
Early symptoms include:
- Changes in gait, including inability to begin walking (gait apraxia)
- Unsteady walking
- Weakness of the legs
- Sudden fall without loss of consciousness or other symptoms (drop attacks)
Symptoms of progression of the disorder:
- Dementia (loss of any or all brain functions, including movement, sensation, perception, and thought processes) - originally mild, may progress to severe dementia
- No observable mood (flat affect)
Frequently asked questions
What is normal pressure hydrocephalus (NPH)?
Normal pressure hydrocephalus (NPH) is a brain disorder caused by blockage of the flow of cerebrospinal fluid, with enlargement of the ventricles within the brain and compression of the brain tissue. It may result in loss of any or all brain functions controlled by the area of the brain which is compressed.
What are the risk factors for normal pressure hydrocephalus (NPH)?
Normal pressure hydrocephalus (NPH) can be a reversible or treatable disorder. It is thought to account for about 5% of all dementias. The incidence is 1 out of 100,000 people. NPH can occur at any age. The onset of symptoms is often gradual. 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 there is an obstruction to the flow of cerebrospinal fluid (CSF). The CSF is produced in normal amounts in this condition, but it is prevented from being normally re-absorbed.
What are the symptoms of normal pressure hydrocephalus (NPH)?
Early symptoms include:
- Changes in gait, including inability to begin walking (gait apraxia)
- Unsteady walking
- Weakness of the legs
- Sudden fall without loss of consciousness or other symptoms (drop attacks) Symptoms of progression of the disorder:
- Dementia (loss of any or all brain functions, including movement, sensation, perception, and thought processes) - originally mild, may progress to severe dementia
Written and revised by
David Cohen, M.D.
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