What is Normal Pressure Hydrocephalus (NPH)?

Normal pressure hydrocephalus (NPH) is a chronic neurological disorder that affects an estimated 700,000 Americans.

Primarily affecting adults over the age of 60, NPH is often misdiagnosed as Alzheimer’s disease or Parkinson’s disease, or its symptoms are thought to be the result of the natural aging process. With proper diagnosis, however, NPH can be controlled with treatment.

Causes

NPH occurs when excess cerebrospinal fluid slowly accumulates in the brain's ventricles, fluid-filled cavities.

Because the ventricles expand slowly as they fill with excess fluid, intracranial pressure is often measured as “normal” during a spinal tap, hence the condition’s name. However, the enlarged ventricles can disrupt and damage nearby brain tissue, thus causing NPH symptoms.

In most cases, it is not known why the fluid buildup happens, but NPH can occasionally be linked to other brain disorders like hemorrhages, infections or inflammation.

Symptoms

NPH may be accompanied by some or all of the following cardinal symptoms:

• Difficulty walking. People with NPH may walk with a “magnetic gait,” using wide, short, slow and shuffling steps. They may also have trouble picking up their feet, walking up stairs and turning. Gait disturbance is often the first symptom to become apparent and is usually the most pronounced.
• Mild dementia. Cognitive symptoms may include a general slowing of thought processes, apathy, impaired planning and decision-making abilities, reduced concentration and changes in personality and behavior.
• Impairment of bladder control. Mild cases of NPH may be characterized by urinary frequency and urgency, while urinary incontinence may occur in more severe cases.

Family members of or those close to the person with NPH are usually the first to recognize these symptoms.

Diagnosis

Because the symptoms of NPH may overlap with those of other types of dementia, it is recommended that a person with suspected NPH undergo examination by a neurologist that specializes in cognitive disorders.

If NPH is suspected, brain imaging such as magnetic resonance imaging (MRI) may be used to visualize the brain ventricles. If symptoms and MRI results strongly suggest NPH, a large-volume spinal tap may be used to determine if the patient could benefit from a shunt.

Treatment

NPH can sometimes be treated with the surgical insertion of a shunt, a long, thin tube that works by draining excess fluid from the brain to the abdomen. This procedure is most likely to help improve gait disturbances, while cognitive changes and bladder control are less likely to be affected.

Drugs that remove excess fluid throughout the body, such as diuretics, and other nonsurgical treatments have not been proved to be effective.