Normal Pressure Hydrocephalus (NPH)

What happens in NPH

Hydrocephalus means too much fluid in the brain's ventricles. Cerebrospinal fluid (CSF) cushions the brain and spinal cord. It is made in the ventricles and absorbed back into the blood. In NPH, absorption is impaired, so the ventricles enlarge. Pressure measured by lumbar puncture is normal or only slightly raised, which is why it is called "normal pressure." The enlarged ventricles stretch nerve fibers that control walking, bladder and thinking.

Types

• idiopathic NPH: no known cause; the most common form in older adults
• secondary NPH: after subarachnoid hemorrhage, head injury, meningitis or brain surgery; can occur at any age. Both are forms of communicating hydrocephalus.

Symptoms

Walking (gait) problems

Usually the first and most noticeable symptom:

• slow, short, shuffling steps
• feet that seem "stuck" or "magnetic" to the floor
• wide-based, unsteady walk
• difficulty starting, turning and climbing stairs
• frequent falls (see gait disorder)

Bladder problems

• urgency and frequency
• incontinence, often with reduced concern about it
• getting up at night to urinate

Thinking problems

• slowed thinking and responses
• apathy and reduced motivation
• poor attention and planning
• memory problems, usually milder than in Alzheimer's disease

Not everyone has all three symptoms.

NPH vs Alzheimer's and Parkinson's

NPH can coexist with these conditions and other forms of dementia, which complicates diagnosis.

Diagnosis

1. neurological exam and timed walking tests
2. brain MRI or CT: shows enlarged ventricles out of proportion to brain shrinkage, with specific patterns (such as narrowing of spaces at the top of the brain)
3. lumbar tap test: removing 30 to 50 ml of CSF through a lumbar puncture, then reassessing walking within hours to a day; improvement predicts shunt success
4. extended lumbar drainage over a few days in a hospital, for more accurate prediction
5. neuropsychological testing and bladder assessment

Treatment

Shunt surgery

A ventriculoperitoneal (VP) shunt is a thin tube placed in a ventricle, tunneled under the skin and draining into the abdomen. A valve controls the flow, and many modern valves can be adjusted with a magnet from outside.

• walking improves most often and most reliably
• bladder control often improves
• thinking improves less consistently, especially if dementia is advanced

Best results occur in people with clear walking problems, a short symptom duration, and a positive tap test.

Risks of shunts

• infection
• blockage or malfunction, needing revision
• over-drainage causing headaches or bleeding around the brain (subdural hematoma)
• seizures (uncommon)

A lumboperitoneal shunt or endoscopic procedures are alternatives in selected cases.

Other care

• physical therapy and walking aids for fall prevention
• bladder management
• support for thinking and memory difficulties

Outlook

Many carefully selected patients improve significantly after shunting, especially in walking. Benefits can persist for years, though symptoms may gradually return with age or other conditions. Without treatment, NPH usually worsens slowly.

Frequently asked questions

What are the symptoms of normal pressure hydrocephalus?

The classic triad is difficulty walking (slow, shuffling, wide-based steps), bladder urgency or incontinence, and slowed thinking or memory problems. Walking difficulty is usually the first and most prominent symptom.

How is NPH different from dementia?

In NPH, walking problems usually come first, before memory loss, and brain scans show enlarged ventricles. In Alzheimer's disease, memory loss comes first. Unlike most dementias, NPH can improve with a shunt to drain excess fluid.

How is normal pressure hydrocephalus diagnosed?

Doctors look for the typical symptoms, enlarged ventricles on MRI or CT, and improvement in walking after removing spinal fluid through a lumbar tap test or drain. These tests help predict who will benefit from a shunt.

Does a shunt cure normal pressure hydrocephalus?

A shunt does not cure the underlying cause but drains excess fluid. Walking improves in many carefully selected patients, bladder symptoms often improve, and thinking sometimes does. Benefits can last years but may lessen over time.

What is the life expectancy with normal pressure hydrocephalus?

NPH itself is not usually fatal, but untreated walking problems and falls can lead to injuries and reduced independence. Successful shunting improves mobility and quality of life. Life expectancy depends largely on age and other health conditions.