Normal pressure hydrocephalus: symptoms, treatment and diagnosis

The NHS says NPH can sometimes be treated with a shunt, but not everyone with NPH will benefit. A shunt is a thin tube implanted in the brain that drains excess cerebrospinal fluid (CSF), usually to the tummy, where it is absorbed into the blood. A valve inside the shunt controls the flow so the fluid does not drain too quickly, and you can feel it as a lump under the skin of the scalp.

Shunt surgery is done by a neurosurgeon under general anaesthetic, usually takes 1 to 2 hours, and may need a stay in hospital of a few days. Because there is a risk of complications, tests are used first to assess whether the likely benefits outweigh the risks.

The Alzheimer's Society says surgery can help with the movement symptoms of NPH but is not always effective for the symptoms of dementia related to memory and thinking. The NHS says an endoscopic third ventriculostomy (ETV) is an alternative to a shunt for hydrocephalus in general, although it is not suitable for everyone and is mainly an option when a blockage is the cause.

After a shunt is fitted, further treatment may be needed if it becomes blocked or infected, and the NHS says a shunt repair operation is then needed. Your surgeon should discuss possible complications with you before surgery.

The NHS says NPH has 3 sets of distinctive symptoms, affecting how you walk, the urinary system and mental abilities. It says symptoms tend to affect older people and usually develop slowly. The Alzheimer's Society, by contrast, says that unlike more common causes of dementia the symptoms usually progress quickly, over just a few months.

The first noticeable symptom is usually a change in the way you walk. You may find it hard to take the first step, as though frozen to the spot, or you may shuffle. The Alzheimer's Society describes a "magnetic" gait, where the feet appear stuck to the floor. As the condition progresses you may become unsteady and more likely to fall, particularly when turning.

The change in walking is often followed by urinary symptoms: a frequent or urgent need to pee, or loss of bladder control. Thinking also slows, so a person may be slow to respond to questions, react slowly to situations or take longer to process information. The Alzheimer's Society adds difficulty staying focused, problems with organising and planning, memory problems for recent events and increased confusion.

The brain is surrounded by cerebrospinal fluid (CSF), which the NHS says protects the brain from damage, removes waste products and provides nutrients. The brain constantly produces new CSF, about a pint a day, while old fluid is absorbed into the blood vessels. Hydrocephalus occurs when this balance is interrupted and fluid builds up.

In normal pressure hydrocephalus the Alzheimer's Society explains that too much fluid builds up in the brain without increasing pressure in the brain tissue. That is why it is called normal pressure, and why it behaves differently from the type of hydrocephalus that starts in babies and children, where pressure rises and causes headache and vomiting.

The NHS says NPH can be difficult to diagnose because symptoms start gradually and resemble more common conditions such as Alzheimer's disease. Doctors assess how you walk, your mental ability, symptoms that affect your bladder control and the appearance of your brain on scans. A checklist is used to help diagnose NPH, and you may not have all the symptoms.

Further tests may be done to decide whether you would benefit from surgery. A lumbar puncture takes a sample of CSF from the lower spine and checks its pressure; removing some CSF may improve symptoms, which suggests surgery could help. A lumbar drainage test drains a larger amount of CSF over a few days under local anaesthetic to see whether symptoms improve. A lumbar infusion test injects fluid into the lower spine while pressure is measured; if the body cannot absorb the extra fluid, the pressure rises, which could indicate NPH and that surgery will help.

The Alzheimer's Society says that, unlike more common causes of dementia, the symptoms of NPH usually progress quickly, over just a few months. It adds that health professionals often mistakenly think the symptoms are being caused by more common health conditions.

The NHS notes that the symptoms happen gradually and are similar to those of other, more common conditions, which is why diagnosis can be difficult. A combination of walking difficulty, bladder symptoms and thinking changes is worth mentioning to a GP, including when someone has already been told they have dementia.

For most people the cause is not known. The Alzheimer's Society says it sometimes develops after a person has recovered from a head injury, a brain haemorrhage or severe meningitis. The NHS says it can sometimes develop after an injury or a stroke, but in most cases the cause is unknown.

The NHS says to call a GP or use NHS 111 if you think you or your child may have symptoms of hydrocephalus. See a GP if you or a family member has a new or worsening problem with walking, balance, memory, thinking or bladder control, and ask whether NPH could be considered, including if dementia has already been suggested. It helps to note when each symptom began, in what order, and whether there have been falls.

Headache, sickness, blurred vision and sleepiness can happen in other forms of hydrocephalus. The NHS says symptoms of acquired hydrocephalus can include a headache that may be worse in the morning, sickness, confusion and sleepiness that can progress to a coma. Get urgent medical help for sudden severe symptoms or rapidly increasing drowsiness or confusion.

Even after treatment, many people need support with mobility, safety and memory. A physiotherapist can assess walking and falls risk, an occupational therapist can advise on home adaptations, and a continence nurse can help with bladder symptoms. If a shunt is fitted, you will need to know the signs of blockage or infection and who to call.

Shine, the spina bifida and hydrocephalus charity, is named by both the NHS and the Alzheimer's Society as a source of specialist support for anyone living with hydrocephalus. The Alzheimer's Society also provides information and a support line for people affected by dementia.

On the NHS the route is from the GP to a neurologist, geriatrician or memory service, and then to a neurosurgical centre for shunt assessment and surgery. Private neurologists and neurosurgeons can offer faster scans and opinions, and may arrange surgery privately. Because the benefit of a shunt depends on selecting the right patients, ask which tests are used to decide, how many such operations the surgeon performs, and what follow-up for the shunt is arranged.