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Brain scans are used to diagnose hydrocephalus, or fluid on the brain.

Congenital and acquired hydrocephalus

CT scans and MRI scans are often used in combination to confirm a diagnosis of hydrocephalus present from birth (congenital) and hydrocephalus that develops later in children and adults (acquired).

These scan the brain in greater detail. They can show the build-up of fluid on the brain and the increased pressure, as well as highlighting any structural defects that may be causing the problem.

Sometimes congenital hydrocephalus is detected before birth during an ultrasound scan.

Normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) can be difficult to diagnose because the symptoms come on gradually and are similar to those of more common conditions, such as Alzheimer's disease.

It's important to make a correct diagnosis because, unlike Alzheimer’s disease, the symptoms of NPH can be relieved with treatment.

Your doctors will assess:

NPH may be diagnosed if you have walking, mental and bladder problems, and cerebrospinal fluid (CSF) levels are higher than usual. However, you may not have all of these symptoms.

Further tests may also be carried out to decide whether you would benefit from having surgery, such as a:

Lumbar puncture

A lumbar puncture is a procedure where a sample of CSF is taken from your lower back. The pressure of the CSF sample is then checked.

Removing some CSF during a lumbar puncture may help improve your symptoms.

If this is the case, it's a good indication that you may benefit from treatment with surgery – see treating hydrocephalus to find out more.

Lumbar drain

You may have a lumbar drain if a lumbar puncture does not improve your symptoms.

A tube is inserted between your back bones to drain a large amount of CSF. This is carried out over a few days to see whether your symptoms improve. The procedure is usually carried out under local anaesthetic.

Lumbar infusion test

During a lumbar infusion test, fluid is slowly injected into your lower back while measuring the pressure.

Your body should absorb the extra fluid and the pressure should stay low. If your body cannot absorb the extra fluid, the pressure will rise, which could indicate NPH and that surgery will be beneficial.