Health Encyclopedia

Normal pressure hydrocephalus (NPH)

Definition

Normal pressure hydrocephalus (NPH) is a rise in cerebrospinal fluid (CSF) in the brain that affects brain function.

Alternative Names

Hydrocephalus - idiopathic; Hydrocephalus - adult; Hydrocephalus - communicating; Extraventricular obstructive hydrocephalus

Causes, incidence, and risk factors

Normal pressure hydrocephalus (NPH) is a form of hydrocephalus, also known as "water on the brain," which means there is too much fluid pressing on the brain.

NPH can occur without a known cause, or it may be caused by any condition that blocks the flow of cerebrospinal fluid (CSF). The fluid-filled chambers (ventricles) of the brain enlarge to fit the increased volume of CSF. They press down on and damage or destroy brain tissue.

Risk factors include:

Bleeding from a blood vessel or aneurysm in the brain (subarachnoid hemorrhage)
Closed head injury
Meningitis or similar infections
Surgery on the brain (craniotomy)

CSF is produced in normal amounts in these conditions, but it is prevented from being reabsorbed normally.

NPH is thought to account for about 5% of all dementias.

Symptoms

The symptoms often begin slowly.

Early symptoms include:

Changes in gait, including inability to begin walking (gait apraxia)
Sudden fall without loss of consciousness or other symptoms (drop attacks)
Unsteady walking
Weakness of the legs

Symptoms as the disorder gets worse:

Apathy
Dementia
Difficulty paying attention
Impaired memory
Less spontaneous behavior
No mood (flat affect)
Speech impairment
Urinary or bowel incontinence
Withdrawn behavior

Signs and tests

An examination shows walking (gait) changes related to the damage in the brain. Deep tendon reflexes may be increased in the lower legs.

Tests include:

Treatment

The goal of treatment is to improve symptoms. The treatment of choice is surgery to place a tube called a shunt that routes the excess CSF out of the brain ventricles.

Treatment may vary depending on the symptoms and how much the therapy relieves them.

Expectations (prognosis)

If there is a known cause and the cause can be corrected, the symptoms may be reversed or at least stopped from getting worse. Without treatment, symptoms often get worse and could lead to death.

Surgical treatment improves symptoms in about 50% of cases. People with minimal symptoms have the best outcome. Other people may have different degrees of disability.

Complications

Complications of surgery (infection, bleeding)
Dementia
Injury from falls
Shortened life span
Side effects of medications
Temporary or permanent loss of brain functions

Calling your health care provider

Call your health care provider if you have symptoms of normal pressure hydrocephalus.

Call your health care provider if a person with NPH worsens to the point where you are unable to care for the person yourself.

Go to the emergency room or call the local emergency number (such as 911) if a sudden change in mental status occurs. This may mean that another disorder has developed.

Prevention

Treating disorders that lead to NPH may prevent it in some cases. It may not be preventable in other cases, but early treatment may prevent severe symptoms.

References

Goetz CG, ed. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: WB Saunders; 2007.

Review Date:2/13/2008
Reviewed By:Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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