Normal Pressure Hydrocephalus

What is normal pressure hydrocephalus?

Hydrocephalus happens when too much fluid builds up in the brain. The fluid is called cerebrospinal fluid (CSF). CSF helps cushion the brain and spinal cord from injuries. It also helps keep the right balance of nutrients in the nervous system. CSF is made in the parts of the brain called ventricles. Every day your body makes a certain amount of CSF and that same amount of CSF is normally reabsorbed by the bloodstream.

Normal pressure hydrocephalus (NPH) is a type of fluid buildup that is most common in adults over the age of 60. If you have NPH, too much CSF slowly builds up inside your brain. This buildup of CSF causes the ventricles of the brain to get bigger. The outer part of the brain (called the cortex) gets compressed against the inside of the skull. The compression also affects the middle and lower parts of the brain (called the mid-brain and brainstem).

Small increases in CSF do not cause problems. Bigger increases may cause problems with walking or memory. Some people who have symptoms of dementia, Alzheimer's disease, or Parkinson's disease may actually have NPH.

How does it occur?

NPH may happen because your brain makes too much CSF or the body may not absorb the CSF properly. It is not always known why this happens. Sometimes brain injury or surgery can cause hydrocephalus. It may also be caused by tumors, infections, or bleeding or bulging blood vessels in the brain.

What are the symptoms?

The 3 most common symptoms of NPH are:

• Trouble walking. You may feel mildly off balance, or you may not be able to stand or walk at all. Your walking stride may be short, slow, and shuffling. You may walk with your feet spread wide apart. You may have trouble picking up your feet. This can make it hard to go up and down stairs and curbs, and can cause falls. Trouble walking is often the first symptom of NPH.
• Memory problems. You may lose interest in daily activities, be forgetful, have trouble dealing with daily tasks, or have short-term memory loss.
• Loss of bladder control. You may feel the need to urinate more often than usual or have strong, urgent needs to urinate. Sometimes people with NPH need to urinate as often as every 1 to 2 hours. The urge to urinate is sometimes so strong that it cannot be held back and urine may leak.

Not all people with NPH have all of these symptoms.

How is it diagnosed?

There are no simple tests for NPH. If you have 2 or all 3 of the major symptoms described above, you may have a CT or MRI scan of the brain.

• CT scan (computerized tomography): This test creates a picture of the brain with X-rays and a special scanner. A CT scan will show if the ventricles are bigger than normal or if there is a blockage.
• MRI: MRI uses radio signals and a strong magnet to create a picture of the brain. The MRI provides more information than the CT, and is often the test of choice.

A neuropsychological test may be done. This test involves a series of questions. It helps check for a loss of brain function. Patterns of problems that show up with a neuropsychological test help sort out dementia from memory problems caused by NPH.

How is it treated?

The treatment of choice is usually surgery to put in a shunt. The shunt is made up of a tube and a valve. When fluid builds up in the brain, a one-way valve in the shunt opens, and the excess fluid drains away from the brain. The shunt allows the fluid to drain somewhere else in the body, usually the abdomen. Fluid is easily absorbed by the abdomen and does not cause any problems.

The technical name for the most common shunt is ventriculoperitoneal shunt. It is also called a VP shunt. The shunt tubing runs from your skull, under the skin, and down through your neck and chest. It ends in the space between your intestines and your abdominal wall. This space is a safe place to dump the extra CSF. When the shunt works well, the compression of CSF on brain tissue stops, and you get better.

Sometimes NPH that can be treated without a shunt—for example, when the NPH is caused by a blockage in the outflow channel from the ventricles to the space around the brain. The surgeon creates a small drainage path from a ventricle to the space around the outside of the brain. This bypasses the blockage and lets the CSF in the ventricles drain out.

How can I help take care of myself?

You must get regular checkups with your surgeon to make sure the VP-shunt is working.

How you take care of yourself depends on what types of problems the NPH is causing. If you have mild NPH and a working shunt, you can live a normal life without taking many precautions. If you have urine leakage problems, you may have to wear protective pads or you may need a catheter to drain the urine. If you have lots of walking and memory problems, you may need to live in a protected place with family or caregivers to help you.

How long will the effects last?

Without treatment, the symptoms of NPH tend to get worse over time. As a general rule, the earlier you get treatment, the better the results. If the cause of NPH is known, surgery is usually very successful. In cases in which a cause is not known, the success rate may range from 25% to 74%.

Your symptoms may get better within days after shunt surgery, or they may not improve for weeks or months. There is no way to predict how fast or how much symptoms will improve. Most people with NPH can lead a normal life. Shunts are very reliable. However, NPH is an ongoing (chronic) condition.

How can I help prevent NPH?

Unfortunately, no one knows how to prevent NPH.