Normal pressure hydrocephalus (NPH): walking, memory and bladder changes

Cerebrospinal fluid (CSF) is made in fluid-filled chambers called ventricles, flows through them to the spinal canal and back up again, and is reabsorbed. Hydrocephalus is a build-up of that fluid. In NPH the ventricles become enlarged although the pressure is often normal when measured, which is where the name comes from.

Most cases have no known cause and are called primary NPH. Secondary NPH follows a known event such as head injury, subarachnoid haemorrhage, brain tumour, bleeding, infection or brain surgery, according to the St George's information. Plymouth's leaflet adds that there is no single test or scan that can say whether someone has NPH, which is why specialist assessment matters.

The three classic features are difficulty walking, progressive impairment of memory and thinking, and impaired bladder control. They can appear at different stages and with different severity. Plymouth says NPH should be considered in older adults with deteriorating walking or balance, cognitive impairment, and urinary urgency or incontinence, and that the vast majority of people with NPH have some gait and balance difficulty.

Shine describes NPH as often mistaken for Alzheimer's or Parkinson's. For older people and families this has a practical meaning: if a relative has become slow, unsteady and shuffling, is having falls and urgency, and has been told it is just ageing or dementia, it is reasonable to ask whether a brain scan has looked at the ventricles and whether NPH has been considered.

• Walking: slower, unsteady, difficulty with balance.

• Thinking: slowed thinking, attention and memory problems.

• Bladder: urgency or leaking.

• Falls and reduced independence often bring people to attention.

Plymouth's service says people with suspected NPH can be referred by any healthcare professional, usually a neurologist, elderly care doctor, GP or old age psychiatrist, when these symptoms are present and a CT or MRI scan shows enlarged ventricles. St George's says that once NPH is confirmed by a neurologist or its neurology NPH clinic, a person may be referred to a neurosurgeon to discuss surgery; it accepts referrals from anywhere in England. Services and access vary between areas, so ask your local team how referrals are handled.

At a first specialist appointment, the Plymouth leaflet explains, you are asked about symptoms, medical history and daily activities; scans are reviewed; you are asked to walk a short distance (10 metres) as well as you can with any usual aid; and you do memory and thinking tests. It suggests attending with a relative or close friend and bringing walking aids, reading glasses and hearing aids.

Further investigations may include MRI of the head and spine. Plymouth describes two tests that mimic the effect of a shunt. In a lumbar puncture (tap test), under local anaesthetic, a small needle is inserted into the lower spinal canal and about 40 to 50 mls of spinal fluid is drained; the test usually takes about 30 to 45 minutes, and walking and memory tests are repeated about an hour later. Some people go home the same day and are asked to keep a diary for 7 days. Improvement may wear off over a few days.

An extended lumbar drain involves a small flexible tube in the lower spinal canal and a stay of 2 to 3 days, removing fluid slowly; Plymouth calls it the most sensitive test for diagnosing NPH. Blood thinners and aspirin need advance discussion with the team: the leaflet advises not to take aspirin for pain relief 7 days before the procedure and to tell the team about anticoagulant or antiplatelet medicines so they can advise when it is safe to stop them. Never stop these on your own initiative.

A shunt is a flexible tube placed in the ventricles to divert excess CSF, usually to the abdomen where it is absorbed. St George's explains the ventriculo-peritoneal shunt has three parts under the skin: a ventricular catheter, a valve that regulates flow (often adjustable) and an abdominal catheter. Plymouth says the operation is done under general anaesthetic, with the valve sitting under the skin, usually behind the ear.

Risks listed by Plymouth include infection, particularly in the first few months; blockage or malfunction leading to recurrent symptoms and possibly further surgery; and over-drainage, which can cause headaches, dizziness or lethargy, alongside general surgical risks. St George's says people are usually in hospital at least one night, have a brain CT and chest and abdomen X-rays to confirm placement, and have a telephone follow-up four weeks later. Plymouth says a CT head scan follows at 4 to 6 weeks, clinic review at about 3 months, and that shunt settings can be adjusted according to response.

St George's says the majority of those properly diagnosed and screened for shunt responsiveness experience improvement, though it can take weeks or months to see the full effect. Early diagnosis and treatment are often a better indicator of success, but people who have had symptoms for many years may still improve. Because a shunt slows progression rather than curing, benefit can fade over time and long-term follow-up matters.

Plymouth notes you must not drive after the operation and must inform the DVLA, with a return to driving normally allowed about 6 months afterwards. Families can help by keeping a record of walking, memory and bladder changes before and after tests, bringing a companion to appointments, and ensuring all medicines are listed.