You may have noticed that a parent is walking more slowly. Their steps are shorter, they hesitate before starting, turning is difficult, or they have begun avoiding walks. At the same time, they are more forgetful or need longer for tasks that used to be simple. Families often put these changes down to age, and sometimes that is the explanation. But some situations deserve investigation precisely because they may be treatable.
One is normal pressure hydrocephalus, also known as NPH. The circulation and absorption of cerebrospinal fluid change, and the cerebral ventricles, the cavities within the brain containing this fluid, enlarge. The name can be misleading. ‘Normal pressure’ does not mean that everything is normal, nor can a single pressure measurement establish the diagnosis.
Which signs should draw our attention?
The most characteristic sign is usually walking: short steps, difficulty starting, unsteadiness and problems turning. Slower thinking, reduced attention, lack of initiative or urinary symptoms may follow, especially a sudden, hard-to-delay need to urinate. These do not all appear at the outset. Walking often changes before the family notices the other signs.
None of these signs is specific to hydrocephalus. Parkinson's disease and other neurodegenerative conditions, strokes, cervical spine disease, neuropathies, orthopaedic problems and even some medicines can cause similar symptoms. Diagnosis therefore requires a complete assessment rather than an impression.
How is the diagnosis made?
It starts with a discussion with the patient and family: when symptoms began, how they have progressed and what has changed in walking and everyday life. Neurological examination and careful gait assessment are essential. A complete brain MRI review may show enlarged ventricles and characteristic changes in the cerebrospinal fluid spaces. However, enlarged ventricles have several possible explanations and are insufficient on their own for a diagnosis.
In suitable cases, a tap test is performed: a quantity of cerebrospinal fluid is removed by lumbar puncture and walking is reassessed after a few hours. Additional tests may sometimes be needed, such as lumbar drainage over several days. Clear improvement strengthens the indication for treatment. However, no obvious improvement after a single test does not exclude the condition. The findings are interpreted together with the clinical examination and imaging.
Can it be treated?
In carefully selected patients, treatment is surgical and involves inserting a ventriculo-peritoneal shunt: a thin tube with a valve that drains cerebrospinal fluid in a controlled way, usually into the abdomen. Modern adjustable valves can be adjusted externally without another operation. The aim is not simply to make the ventricles look smaller on imaging. It is to improve walking and independence.
In 2025, the New England Journal of Medicine published a randomised trial addressing a question debated for many years. All 99 participants had responded favourably to temporary drainage and received a shunt. In half, the valve was open; in the others it remained functionally closed for three months, without the patients or assessing doctors knowing the allocation. Walking and balance improved significantly only in the open-valve group. Over this period, the study found no significant difference between groups in memory, attention or urinary symptoms. The practical conclusion is that treatment may help, particularly walking, but should not be presented as a solution for every memory disorder.
Like any operation, shunt insertion has risks: overdrainage, fluid or blood collections on the surface of the brain, infection or blockage. Age, frailty, associated illnesses and anticoagulant treatment are reviewed before deciding. Postoperative follow-up, including any valve adjustments, is part of treatment.
What to remember
If a parent is having noticeably greater difficulty walking, becomes unsteady and develops changes in attention or memory, this does not automatically mean normal pressure hydrocephalus. Equally, it is unhelpful to attribute everything to ageing. Neurological and neurosurgical assessment can clarify whether a treatable cause is present and which options are appropriate.
If symptoms start suddenly or worsen rapidly, urgent assessment is needed to exclude an acute cause.
The assessment pathway in brief
- Symptoms and progression: walking, attention, memory and urinary function.
- Neurological examination and objective gait assessment.
- MRI/CT and consideration of alternative diagnoses.
- A CSF tap test when indicated; a negative result does not by itself exclude the diagnosis.
- A multidisciplinary decision adapted to the patient's risks and goals.
- A ventriculo-peritoneal shunt in carefully selected patients.
- Clinical follow-up, gait assessment and valve adjustment when needed.