Normal Pressure Hydrocephalus (NPH)

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 produced in parts of the brain called ventricles. Every day your body makes a certain amount of CSF and that same amount of CSF is absorbed in the brain.

Normal pressure hydrocephalus (NPH) is a type of fluid buildup that is most common in adults over the age of 60. In NPH, a buildup of CSF causes the ventricles of the brain to get bigger. This may stretch nerve tissue in the brain and cause symptoms. 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?

One or more of these tests may be done:

• Ultrasound scan: This test uses sound waves to give a picture of the structures in the skull.
• 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 the test of choice in most cases. People with pacemakers or other metal implants cannot have MRI scans.
• Lumbar puncture or spinal tap: After you are given medicine to numb your back, a thin needle is passed into the space between the bones in your lower back. The needle is used to remove some spinal fluid to see if this helps your symptoms get better.
• Neuropsychological test: This test involves asking a series of questions. It helps check for a loss of brain function.

How is it treated?

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

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. If you have a shunt, you will need to have regular medical checkups.

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