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How to Get Diagnosed and Treated for iNPH

How to Get Diagnosed and Treated for iNPH

Idiopathic normal pressure hydrocephalus (iNPH) is a form of dementia that causes fluid build-up in the brain.

Idiopathic normal pressure hydrocephalus (iNPH) is a form of dementia that often masquerades as Alzheimer’s or Parkinson’s, but isn’t either of those diseases. The reason it’s so important to be aware of this condition is because dementia caused by iNPH can be controlled or reversed with the proper treatment. The Hydrocephalus Association estimates that more than 700,000 Americans (twice the number from 10 years ago) have iNPH. The average age of onset is about 70 years old. Men and women are affected in equal numbers, and less than 20 percent receive an appropriate diagnosis and treatment. But if things are “normal,” what’s the problem?

Why brain fluid build-up is bad
In 1964, Dr. Salomon Hakim described the physical symptoms of dementia as gait disturbances and lack of bladder control. Those two symptoms, which is what a good specialist will look for when diagnosing iNPH, were thought to be going on even though there was no perceived fluid build-up in the brain. But now we know that’s wrong: there’s fluid—and hence pressure—build-up in the brain.

With today’s scanning technologies, like a CT or MRI, doctors can see exactly where a build-up of cerebral fluid is occurring. And we know how to alleviate the pressure—and hopefully reverse the symptoms.

The fluid that builds up in the brain and causes the debilitating symptoms is called cerebrospinal fluid (CSF). It originates deep in the brain, flows out and around it, and into the spinal canal and subdural space around the spinal cord. Your body maintains about 150 ml (2/3 of a cup) while producing a total 500 ml a day of this fluid (you pee out the rest). The fluid acts as a cushion, an auto-regulating cerebral cleaner, and a helper for cerebral blood flow. Usually it’s reabsorbed or flushed through the system, but for some reason, we’re not entirely sure why in iNPH, the reabsorption process of that extra 350 ml a day is interfered with and CSF build-up occurs.

Getting proper diagnosis and treatment
After finding a neurologist who specializes in this condition, get an exam—and maybe a second opinion. Then, if it looks like you’re a candidate for treatment, you’ll have a CT scan or an MRI. What the doctors are looking for are enlarged ventricles in the brain—there are four—that become engorged due fluid backup.

If they find what looks like harmful CFS pressure build-up, the next step is an external lumbar drainage (spinal tap), which will identify folks who will respond to shunt surgery. The shunt is a drain that’s placed either at the base of the brain or in the spine (wherever your specialist deems appropriate) to relieve the build-up of CSF. The shunts are programmable and deliver the excess fluid to a part of the body (sometimes the bladder) that will help you excrete the fluid. Properly selected patients who receive the shunt have a 60 and 80 percent chance of improvement.

So if you or someone you know has the onset of a foot-dragging, shuffling gait to one side, is experiencing incontinence and/or exhibiting signs of depression and short-term memory loss, take action now. There’s no reason for anyone to go through a misdiagnosis of Alzheimer’s or Parkinson’s when the problem is actually iNPH.

Medically reviewed in February 2020.

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