What is Normal Pressure Hydrocephalus?
Normal pressure hydrocephalus (NPH) is an excessive build-up of fluid in the head.
Under normal conditions cerebrospinal fluid (CSF) circulates through the brain, its ventricles and around the spinal cord, acting as a protective cushion and provider of nutrients. About a pint of CSF is produced daily in the adult brain.
NPH results when the flow of CSF is blocked in some way. It occurs most often in people aged over 60.
What are the symptoms?
The three main symptoms are mobility problems, forgetfulness/confusion (dementia) and urinary incontinence.
However, diagnosis is still difficult due to some of the symptoms being similar to other disorders, e.g. Alzheimer's, Parkinson's disease or simply increasing age. Many cases go completely unrecognised and are never treated.
Dementia will include short -term memory loss, forgetfulness and difficulty in dealing with everyday tasks. Because these symptoms appear gradually and are commonly associated with old age, many people think they are normal and assume they must learn to live with their problems.
Mobility problems may include a shuffling or wide based gait which could result in frequent falls.
Urinary incontinence is usually the last symptom to appear, often starting when someone has difficulty in getting to the toilet in time.
What causes it?
For most patients the cause is unknown.
In some cases an imbalance in the production or absorption of CSF causes the hydrocephalus.
How common is it?
Normal pressure hydrocephalus is not that common; however UK research suggests that up to 2% of patients in the UK aged 60 and over who are thought to have dementia may in fact have NPH. This 2% could represent up to 10,000 people who may be suitable for assessment for treatment.
How is it diagnosed?
A GP should consider referring patients with the three main symptoms to a neurologist or geriatrician.
While it can be difficult to diagnose, the most common diagnostic tools are neuro-imaging devices - such as computerised tomography (CT) or magnetic resonance imaging (MRI) - and a careful clinical assessment; this usually involves a lumbar puncture, when a thin needle is passed into the spinal fluid space30.05.06ne to see if the symptoms are temporarily relieved.
Can it be treated?
Generally, the earlier the diagnosis the better chance of successful treatment.
Assessment of suitability for a shunt varies between hospitals but investigations may include an MR scan; measuring the pressure inside the head either by lumbar puncture or by an intracranial pressure measuring device inserted under anaesthetic through the skull under the scalp and by drainage of CSF by lumbar puncture for a few days to see if a patient improves.
Treatment is by operation when a fine tube and valve (called a shunt) is inserted into one of the spaces of the brain to drain away excess fluid. The fluid is diverted to another part of the body (usually the abdomen), where it is reabsorbed into the bloodstream.
People will respond to the operation in different ways and while in most cases an improvement results (the success rate for shunting can be as high as 80%), the level of this improvement will vary. The rate of improvement will also vary considerably between patients.
Case Studies
Bart Bainbridge
Wendy Simons