What is Normal Pressure Hydrocephalus (NPH)?

What is Normal Pressure Hydrocephalus?

Normal Pressure Hydrocephalus (NPH) is a condition which mainly affects people over 60.

A clear fluid, cerebrospinal fluid (CSF) is constantly produced and absorbed, and flows through chambers within the brain, (ventricles) and around the outside of the spinal cord. CSF protects the brain and spine, provides them with nutrients, and removes toxins.

When more CSF is produced than absorbed, hydrocephalus occurs. In NPH the ventricles become enlarged by too much CSF building up, although the pressures inside the head are often found to be normal. The condition is associated with several symptoms, including difficulty walking, cognitive impairment/dementia, and urinary incontinence.

You can read about the condition in more detail in our specialist NPH resources.

 

Types of NPH

There are two main forms of NPH:

• Idiopathic - In most people with NPH, no cause can be found. This is termed Idiopathic.

  Secondary NPH - Secondary NPH occurs as a result of previous blockage or head injury. It may occur many years after injury, or develop when untreated hydrocephalus that has been stable for many years begins to cause symptoms.

What causes NPH?

In many people, the cause of NPH is not known but it is usually associated with older age.

In some people NPH can be caused by a previous head injury, a bleed in the brain, or because of infection or a tumour blocking the flow of the CSF. In some cases, the cause can be reduced CSF flow owing to stenosis (narrowing) of the aqueduct which is a part of the ventricular system. In NPH the excess fluid and enlarged ventricles press on the blood vessels and brain tissue. This can alter the way the brain works, and prevent the brain from removing toxins. These toxins can then build up in the brain and begin to harm brain cells, leading to dementia and loss of brain volume.

 

What are the symptoms of NPH?

Increasing difficulty walking is often the first symptom noticed. The pattern of walking (gait) can become slow and shuffling, with difficulty picking the feet up (sometimes described as ‘magnetic gait’ or ‘sticky feet’) or a wide based stance.

Difficulty walking occurs because the enlarging ventricles press on the part of the brain that controls movement of the legs. Balance problems and falls (especially backwards) are also common.

Cognitive impairment in NPH may appear to be like Alzheimer’s but it generally progresses at a slower rate, and usually follows difficulties with walking rather than being the first symptom to appear. In addition to memory difficulties, there may be problems with attention and slowness of thought. Some people’s behaviour may change, especially if the frontal lobe is under pressure. This part of the brain usually helps us monitor our behaviour so it is appropriate to the situation we are in, people with frontal lobe impairment may behave with fewer inhibitions or regard for social norms than previously.

Many people also experience issues with their mental health, such as depression or anxiety, or with regulating their mood, becoming agitated, angry or frustrated.

Urinary leakage is more common than bowel leakage, but some people may have either or both. Leakage of urine occurs because the area of the brain controlling bladder function is situated just above the ventricles so is easily affected if the ventricles expand. People with bladder involvement describe urgency and frequency of needing to pass urine, with sudden leakage. If combined with walking difficulties, this can make getting to the toilet in time very difficult.

Headaches and fatigue may occur and can vary in intensity between people. There may also be a wide range of neurological symptoms such as numbness, tingling or weakness in any of the arms, legs, or face.