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. You forget names you knew for decades. You start having accidents you never had before. You tell yourself it’s just getting older. But what if it’s not aging? What if it’s something treatable? That’s the reality for many people with normal pressure hydrocephalus - a condition that mimics dementia but can often be reversed with a simple surgery.

What Is Normal Pressure Hydrocephalus?

Normal pressure hydrocephalus, or NPH, happens when too much cerebrospinal fluid (CSF) builds up in the brain’s ventricles. Unlike other types of hydrocephalus, the pressure doesn’t spike. It stays in the normal range - between 70 and 245 mm H₂O - which is why it’s called "normal pressure." But even though the pressure is normal, the fluid overload stretches the brain tissue, especially around areas that control walking, thinking, and bladder control.

It was first clearly described in 1965 by two neurosurgeons, Salomón Hakim and Raymond Adams. Since then, we’ve learned it mostly affects people over 60. About 0.4% of people over 65 have it. In nursing homes, that number jumps to nearly 6%. And here’s the kicker: up to 60% of these cases are misdiagnosed as Alzheimer’s or Parkinson’s. That means thousands of people are living with a condition that could be fixed - but no one’s checking for it.

The Three Signs: Gait, Cognition, and Bladder Control

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

First, gait trouble. This isn’t just being a little slower. People with NPH develop what doctors call a "magnetic gait." Their feet shuffle, they take short steps, and they seem stuck in place. They might struggle to turn around or step over a curb. In studies, nearly 100% of diagnosed NPH patients have this symptom. It’s often the earliest and most obvious sign.

Second, cognitive changes. This isn’t memory loss like Alzheimer’s. It’s slower thinking, trouble focusing, forgetfulness about appointments, and losing track of conversations. Neuropsychological tests show deficits in executive function - things like planning, organizing, switching tasks. The brain’s frontal lobes get compressed by the swollen ventricles, and that’s what messes with thinking. About 73% of NPH patients show clear cognitive decline.

Third, urinary incontinence. This shows up later, and only in about one-third of cases. But when it does, it’s a red flag. You might not need all three symptoms to have NPH - only 29% of patients have the full triad. But if you have gait trouble plus any one of the other two, you should get checked.

How Is It Diagnosed?

Most doctors don’t test for NPH unless they’re specialists. That’s why it takes, on average, 14 months from when symptoms start to when someone gets the right diagnosis.

The first step is imaging. A CT scan or MRI will show enlarged ventricles. The key measurement is Evan’s index - if it’s 0.3 or higher, that’s a sign of ventriculomegaly. MRI can also spot periventricular edema - fluid leaking into brain tissue around the ventricles - which is a strong clue.

Next comes the CSF tap test. This is simple: a doctor removes 30 to 50 milliliters of spinal fluid with a needle, like a lumbar puncture. Then they measure your walking speed, balance, and thinking ability before and after. If you improve by at least 10% on a timed 10-meter walk or a cognitive test, your chances of responding to a shunt jump to 82%. If you improve by 15% or more, your odds of success are nearly 9 in 10.

Some centers use external lumbar drainage - a catheter left in place for a few days to drain fluid continuously. This gives a better sense of long-term improvement. But the tap test is faster, cheaper, and just as predictive in most cases.

Shunt Surgery: The Only Treatment

There’s no pill for NPH. No drug slows it down. The only proven treatment is surgery - a ventriculoperitoneal (VP) shunt.

Here’s how it works: Two thin tubes are placed. One goes into a ventricle in the brain. The other goes down to the abdomen. They’re connected by a valve that lets excess CSF drain slowly into the belly, where the body absorbs it. The valve is set to open at a pressure between 50 and 200 mm H₂O, depending on the patient.

The surgery takes about an hour under general anesthesia. Most people go home in 2 to 3 days. Recovery takes 6 to 12 weeks. But the results? They can be dramatic.

One 72-year-old man, after his shunt, cut his 10-meter walk time from 28 seconds to 12 seconds - in under two days. He started walking without help again. He regained bladder control after 18 months of accidents.

Studies show 70 to 90% of properly selected patients improve after shunting. Gait improves in 76%, cognition in 62%, and continence in 58% within a year. Most people say their quality of life shoots up - and they’re glad they had the surgery.

Why Do Some Shunts Fail?

Not everyone gets better. About 20 to 30% of shunt surgeries don’t help. Why?

One reason: misdiagnosis. If someone has Alzheimer’s mixed with NPH - which happens in 25 to 30% of cases - the shunt won’t fix the Alzheimer’s part. Another reason: the shunt doesn’t work right. It can get blocked, infected, or overdrain. About 15% of shunts fail within two years. Infection happens in 8.5% of cases. Subdural hematomas - bleeding on the brain - occur in 5.7%.

Older patients, especially over 80, have higher infection rates. That’s why careful patient selection matters. If your tap test shows no improvement, don’t get the shunt. If you’ve had symptoms for over a year, your chances drop by 30%. Time matters.

Different From Alzheimer’s and Parkinson’s

It’s easy to confuse NPH with other brain disorders. But the differences are clear.

Alzheimer’s starts with memory loss - forgetting names, repeating questions. Gait problems come much later, if at all. NPH starts with walking. You can still remember your grandchildren’s names, but you can’t get to the bathroom in time.

Parkinson’s has tremors, stiffness, and slow movement - but not the magnetic gait. Parkinson’s patients often lean forward. NPH patients shuffle with feet flat on the ground, wide-based, like they’re walking on ice.

Vascular dementia comes after strokes - symptoms jump in steps. NPH creeps in slowly, over months.

MRI can tell them apart. NPH shows enlarged ventricles with periventricular edema. Alzheimer’s shows shrinking of the hippocampus. Parkinson’s looks normal on MRI until late stages.

Barriers to Diagnosis and Care

Even though NPH is treatable, it’s underdiagnosed. Why?

Doctors don’t think of it. Families assume it’s aging. Insurance won’t cover the tests. A 2022 survey found 37% of CSF tap tests were denied prior authorization. Medicare covers shunts - but not always the diagnostic steps.

There’s also a lack of expertise. Interpreting CSF dynamics requires training. Few neurologists or neurosurgeons get that. The Hydrocephalus Clinical Research Network says you need over 200 hours of specialized training to do it right.

And then there’s the stigma. People don’t want to admit they’re losing control. They hide the accidents. They avoid walking. They stop going out. By the time they see a doctor, it’s too late for the best results.

What’s New in NPH Research?

There’s hope on the horizon.

In 2022, the FDA approved a device called the Radionics CSF Dynamics Analyzer. It measures how well the brain drains CSF - giving a clearer picture than just pressure readings. It’s improving diagnostic accuracy to 89%.

A new app, the iNPH Diagnostic Calculator, uses 12 clinical factors to predict shunt success with 85% accuracy. It’s being used in clinics from Boston to Berlin.

And researchers are working on blood tests. Three Phase II trials are testing CSF protein markers that could one day diagnose NPH without a spinal tap. Preliminary results show 92% sensitivity.

The Alzheimer’s Association and Hydrocephalus Association teamed up in 2023 to create new guidelines for patients with mixed dementia. The goal? Don’t miss NPH when it’s hiding in plain sight.

What Should You Do?

If you or someone you love is over 60 and showing signs of slow walking, memory lapses, or bladder issues - don’t assume it’s normal aging.

Talk to your doctor. Ask: "Could this be normal pressure hydrocephalus?"

Request an MRI or CT scan. Ask for a CSF tap test if imaging shows enlarged ventricles.

If your doctor says no, get a second opinion - from a neurologist who specializes in movement disorders or dementia, or a neurosurgeon who treats hydrocephalus.

The window for treatment is narrow. But it’s not closed. And the payoff? It’s not just walking again. It’s going back to the kitchen, the garden, the church, the grandkids. It’s dignity.

Long-Term Outlook

Shunts aren’t perfect. Most need at least one revision in their lifetime. The average shunt lasts 6.3 years. But even with revisions, long-term outcomes are good. A 20-year study in Sweden showed 68% of patients kept their improvements.

The key is early action. The sooner you test and treat, the better the result. Delay past 12 months, and you lose 30% of your chance at full recovery.

And while shunts aren’t risk-free, the risks of doing nothing are higher. Untreated NPH leads to falls, fractures, institutionalization, and complete dependence. Many patients end up in nursing homes - not because they’re too old, but because no one looked closely enough.

NPH is not rare. It’s not untreatable. It’s just hidden.