Normal Pressure Hydrocephalus: Gait, Cognition, and Shunts Explained

Imagine waking up one day and realizing you can’t walk the way you used to. Your steps feel stuck, like your feet are glued to the floor. Then you notice you’re forgetting things more often - names, appointments, where you put your keys. And suddenly, you’re having accidents you never had before. If you’re over 65, doctors might shrug and say, “That’s just aging.” But what if it’s not? What if it’s something treatable?

This is the reality for tens of thousands of older adults with normal pressure hydrocephalus (NPH). It’s not Alzheimer’s. It’s not Parkinson’s. And it’s not just getting older. NPH is a hidden neurological condition that mimics dementia but can be reversed - if caught in time.

What Is Normal Pressure Hydrocephalus?

Normal pressure hydrocephalus happens when too much cerebrospinal fluid (CSF) builds up in the brain’s ventricles. These are natural fluid-filled spaces that cushion the brain. In NPH, the fluid doesn’t drain properly, so the ventricles swell. But here’s the twist: the pressure doesn’t spike like in other types of hydrocephalus. That’s why it’s called “normal pressure.” The fluid is there, but the body doesn’t sense it as dangerous - so it doesn’t trigger warning signs until damage is already done.

First identified in 1965 by neurosurgeons Salomón Hakim and Raymond Adams, NPH affects about 0.4% of people over 65 - and up to 6% of nursing home residents. That’s tens of thousands of people in the U.S. alone. Yet, most go undiagnosed. Why? Because its symptoms look exactly like other common brain disorders.

The Three Hallmarks: Gait, Cognition, and Bladder Control

NPH doesn’t hit you with one symptom. It hits you with three - and they come in a specific order.

Gait disturbance is the first and most consistent sign. It shows up in 100% of confirmed cases. People don’t just walk slower. They develop what doctors call a “magnetic gait” - feet shuffle, legs stay wide apart, and they seem stuck to the floor. They can’t start walking easily. Turning is hard. They often fall backward. This isn’t weakness. It’s a brain signal problem. The motor areas controlling walking get compressed by swollen ventricles.

Cognitive impairment follows. It’s not memory loss like Alzheimer’s. It’s slower thinking, trouble planning, getting lost in conversations, forgetting why you walked into a room. Neuropsychological tests show clear frontal-subcortical deficits - think trouble with multitasking or switching tasks. In studies, 73% of NPH patients show this pattern. But unlike Alzheimer’s, their long-term memory stays mostly intact. They remember childhood stories but can’t remember what they ate for breakfast.

Urinary incontinence comes last - and often gets dismissed as a normal part of aging. But it’s not. In NPH, it’s not about weak muscles. It’s about the brain losing its ability to signal when the bladder is full. About one-third of patients experience this. And it’s often the most distressing symptom - leading to isolation, depression, and nursing home placement.

Only about 30% of people have all three symptoms at once. Most have one or two. That’s why NPH is so often missed. A doctor sees memory issues and assumes dementia. A physical therapist sees gait trouble and assumes Parkinson’s. A urologist sees incontinence and prescribes pills. No one connects the dots.

How Is NPH Diagnosed?

Diagnosing NPH isn’t a single test. It’s a puzzle. And the pieces are scattered across imaging, movement tests, and fluid analysis.

First, doctors use MRI or CT scans. They look for enlarged ventricles - specifically measuring something called Evan’s index. If it’s above 0.3, that’s a red flag. They also check for periventricular edema (fluid leaking around the ventricles) and flow voids near the aqueduct - signs that CSF isn’t moving right.

Then comes the CSF tap test. A doctor removes 30-50 milliliters of spinal fluid with a needle - like a spinal tap. Within an hour, they measure how well the patient walks. If their walking speed improves by 10% or more, it’s a strong sign the brain will respond to a shunt. Studies show this test predicts shunt success with 82% accuracy.

Some centers go further with external lumbar drainage - a catheter left in the spine for 2-3 days to drain fluid continuously. This gives a clearer picture of long-term improvement. If walking and cognition improve during this time, shunt surgery is very likely to help.

And yes - doctors also rule out everything else. Alzheimer’s, Parkinson’s, vascular dementia, even vitamin B12 deficiency. NPH is a diagnosis of exclusion. But that’s the problem: most doctors don’t even consider it.

Shunt Surgery: The Only Treatment

There’s no pill for NPH. No drug slows it down. The only treatment is surgery: a ventriculoperitoneal shunt.

This is a small tube placed in the brain’s ventricle, connected to another tube that runs under the skin to the abdomen. A valve in between controls how much fluid drains - usually set between 50 and 200 mm H₂O. The fluid gets absorbed by the belly, just like it’s supposed to.

The surgery takes about an hour. Most people go home in 2-3 days. Recovery takes 6-12 weeks. But the results? They can be life-changing.

Studies show 70-90% of properly selected patients improve after shunting. In one case, a 72-year-old man went from taking 28 seconds to walk 10 meters to 12 seconds - in just two days. Another woman regained bladder control after 18 months of accidents. Many say they feel like themselves again.

But it’s not magic. About 20-30% of shunts don’t work. Why? Maybe the diagnosis was wrong. Maybe the brain has already changed too much. Or maybe the valve setting was off. Shunt malfunction happens in 15% of cases within two years. Infection occurs in 8.5%. Subdural bleeding in 5.7%. These are real risks.

Who Benefits Most From Surgery?

Not everyone with NPH should get a shunt. Timing matters. Research shows that if you wait more than 12 months after symptoms start, your chance of improvement drops by 30%. The brain adapts. Nerves lose their plasticity. The window closes.

Best candidates are people who:

• Have clear gait disturbance as the first symptom
• Have MRI findings matching NPH (enlarged ventricles, periventricular changes)
• Improve significantly after a CSF tap test
• Are under 80 years old with few other serious health problems

Patients with mixed conditions - like NPH plus early Alzheimer’s - are trickier. About 25-30% of NPH cases overlap with other brain diseases. In those cases, shunts still help with gait and bladder control - but memory may not bounce back.

Why Is NPH So Often Missed?

Here’s the ugly truth: NPH is the great masquerader of geriatric neurology.

Doctors are trained to think of dementia as Alzheimer’s. Gait problems as Parkinson’s. Incontinence as age-related. NPH doesn’t fit neatly into those boxes. It’s rare. It’s complex. And it requires a team - neurologist, neurosurgeon, physical therapist - to spot.

On average, patients wait 14 months from first symptom to diagnosis. That’s over a year of lost time. During that time, they’re prescribed memory pills that don’t work. They’re told to use adult diapers. They’re told to accept decline.

Insurance adds another layer. In 37% of cases, insurers deny coverage for the CSF tap test or lumbar drainage - even though these tests prevent unnecessary surgery. A single shunt costs $28,450 on average under Medicare. But the diagnostic tests? Often denied. So patients get stuck.

What’s New in NPH Research?

There’s hope on the horizon.

In 2022, the FDA approved a new device called the Radionics® CSF Dynamics Analyzer. It measures how well the brain drains fluid - giving a more precise diagnosis than imaging alone. In 2023, a smartphone app called the iNPH Diagnostic Calculator started helping doctors predict shunt success using 12 simple clinical clues.

And now, researchers are chasing a blood test. Three clinical trials are testing whether specific proteins in spinal fluid can identify NPH without invasive tests. Early results show 92% accuracy. If this works, diagnosing NPH could become as simple as a blood draw.

The Alzheimer’s Association and Hydrocephalus Association teamed up in 2023 to create new diagnostic guidelines - because too many people are slipping through the cracks.

What Happens After Surgery?

Shunt surgery isn’t the end. It’s the beginning of ongoing care.

Patients need follow-ups at 2 weeks, 6 weeks, 3 months, and 6 months. The valve might need adjusting. Too much drainage causes headaches. Too little means symptoms come back. Some people need revisions within a year. The average shunt lasts 6.3 years before needing replacement.

But the payoff? For those who respond, it’s profound. A 2022 survey of 457 NPH patients found:

• 76% had better walking
• 62% had improved thinking
• 58% regained bladder control
• 89% were happy with their decision

And the biggest win? Independence. 78% of patients said they needed less help from caregivers. They drove again. They cooked. They went out. They stopped hiding.

What Should You Do If You Suspect NPH?

If you or a loved one over 65 has:

• Shuffling or “stuck” walking
• Slowed thinking or trouble making decisions
• Loss of bladder control without other causes

- then ask for a neurological evaluation. Don’t settle for “it’s just aging.”

Ask for an MRI. Ask for a CSF tap test. Ask to see a neurosurgeon who specializes in hydrocephalus. Bring this article. Be persistent. Because NPH is rare - but it’s treatable. And for many, it’s the difference between a slow fade and a second chance.