What is normal pressure hydrocephalus (NPH)?
Normal pressure hydrocephalus (NPH) is a condition that is caused by an abnormal build up of cerebrospinal fluid (CSF) in the ventricles (cavities or spaces) of the brain. Cerebrospinal fluid is a clear liquid that circulates around the brain and spinal cord, cushioning and protecting them from damage. When people have NPH, they have an excess of cerebrospinal fluid because their bodies cannot properly drain and absorb the fluid. This fluid build-up can harm the brain.
The differences between NPH and other forms of hydrocephalus is that even though there is a larger than normal amount of CSF, the pressure inside the ventricles remains the same. This buildup of fluid causes symptoms to occur over time.
Who gets normal pressure hydrocephalus (NPH)?
Normal pressure hydrocephalus most often occurs in people over age 60.
How common is normal pressure hydrocephalus (NPH)?
It is difficult to know how many people actually have normal pressure hydrocephalus (NPH) because its symptoms are similar to other diseases, such as Alzheimer's or Parkinson's disease, or even the natural aging process itself. However, it is estimated that as many as 10 percent of people with dementia attributed to other disorders may actually have NPH.
Symptoms and Causes
What causes normal pressure hydrocephalus (NPH)?
The exact cause of normal pressure hydrocephalus (NPH) is not clear. In most cases of NPH, the cause of the buildup of cerebrospinal fluid (CSF) is unknown. However, in some cases, NPH can occur as a result of other conditions that affect the brain including:
What are the symptoms of normal pressure hydrocephalus (NPH)?
There are three classic symptoms of normal pressure hydrocephalus (NPH):
- Difficulty walking. This problem can be mild or severe. In many cases, people with NPH have trouble picking up their feet. Some describe it as feeling like their feet are stuck to the floor. This can lead to a shuffling walk and problems going up stairs and curbs. It also increases the risk of falling.
- Dementia. This often involves confusion, short-term memory loss/forgetfulness, trouble paying attention, changes in mood, and a lack of interest in daily activities.
- Problems with bladder control. Problems include urinary incontinence (the inability to hold urine), frequent urination, and a strong feeling of needing to urinate.
Diagnosis and Tests
How is normal pressure hydrocephalus (NPH) diagnosed?
Diagnosis begins with a careful review of symptoms and medical history. medical interview and a physical exam. Other tests include:
- Imaging tests. A CT scan or MRI of the head is done to look for enlarged ventricles in the brain.
- Cerebrospinal fluid tests. These tests include a spinal tap and external lumbar drainage. During a spinal tap, a small sample of cerebrospinal fluid is removed and the patient is assessed to see if the symptoms improve. During external lumbar drainage, cerebrospinal fluid is removed through a special catheter (tube) over a 36-hour period to further see if symptoms improve dramatically and to test the potential benefit of implanting a shunt (see treatment).
- Gait analysis (walking). This is a timed walk test. The patient is watched as he or she walks 10 meters (about 30 feet).
- Neuropsychological testing. This involves a series of assessments to determine if there is a loss of brain function (including memory, concentration and problem-solving) due to NPH.
Management and Treatment
How is normal pressure hydrocephalus (NPH) treated?
Although there is no cure for NPH, the symptoms can be managed through surgery. Surgery involves inserting a drainage system called a shunt. One end of the shunt -- which is a long sturdy, flexible plastic tube -- is placed into one of the brain's ventricles. The other end is tunneled under the skin to another area of the body, usually the lower part of the abdomen.
The shunt allows the excess cerebrospinal fluid to drain from the brain and be absorbed back into the body. A valve in the shunt keep the fluid flowing in the correct direction and at the right rate. The shunt remains in the person's body for the rest of his or her life.
What are the complications of treatment?
Complications of normal pressure hydrocephalus (NPH) treatment are those associated with any surgical procedure. They include bleeding, infection, and reaction to the anesthesia used during surgery. Patients might also experience mild abdominal pain. Seizures also may occur as surgery on the brain can affect very sensitive areas of the brain. Fortunately, these complications are not common, and in most cases can be successfully treated.
Is there any way to prevent normal pressure hydrocephalus (NPH)?
Right now, there is no known way to prevent NPH. However, getting treatment as soon as symptoms appear can improve those symptoms and increase the chance for a full or partial recovery.
Outlook / Prognosis
What is the outlook for people with normal pressure hydrocephalus (NPH)?
The chance of a good recovery from NPH is more likely if a patient is diagnosed and treated in the early stages. Some people do not need shunt surgery because the symptoms are not severe enough to affect daily life. People who do not need surgery should continue to have check-ups with a doctor to monitor the symptoms. If the symptoms worsen, the doctor may recommend the surgery. Those who get surgery, often find that their symptoms are manageable.