Diagnosing hydrocephalus 

Brain scans are used to diagnose hydrocephalus (fluid on the brain).

Congenital hydrocephalus

In some cases, an ultrasound scan can be used to detect congenital hydrocephalus before a baby is born. An ultrasound scan uses sound waves to create an image of your womb and the baby inside.

If your baby has physical characteristics of congenital hydrocephalus after they're born, such as an enlarged head, they may be referred for an ultrasound scan. They may also need a computerised tomography (CT) scan or a magnetic resonance imaging (MRI) scan.

These can be used to examine 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 hydrocephalus. 

Acquired hydrocephalus

Hydrocephalus that develops in adults or children (acquired hydrocephalus) can be diagnosed using a combination of CT and MRI scans. The scans can also reveal possible causes of your symptoms, such as a brain tumour.

Normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) usually develops in older people and can be difficult to diagnose. This is 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, it's possible to relieve the symptoms of NPH with treatment.

A diagnostic checklist will be used to examine:

  • how you walk (your gait)
  • your mental ability
  • symptoms that affect your bladder control, such as urinary incontinence
  • the appearance of your brain during CT, MRI and ultrasound scans

You may be diagnosed with NPH if you have an impaired gait, slowing of the normal mental processes and urinary incontinence, and scans have shown that your cerebrospinal fluid (CSF) is at a higher level than usual. However, you may not have all of the symptoms on the above checklist.

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

  • a lumbar puncture
  • a lumbar drainage test
  • a lumbar infusion test

These procedures are described below.

Lumbar puncture

A lumbar puncture, also known as a spinal tap, is a procedure used to take a sample of CSF from your lower back.

A small amount of fluid is removed from the area between your back bones (vertebrae). The pressure of the CSF sample can then be 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).

Lumbar drain

You may have a lumbar drain if a lumbar puncture doesn't 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 if your symptoms improve. The procedure is usually carried out under local anaesthetic.

Lumbar infusion test

A lumbar infusion test involves slowly injecting fluid into your lower back while measuring the pressure. The additional fluid should be absorbed by your body so the pressure stays low. However, if your body can't absorb the extra fluid, the pressure will rise which could indicate NPH and that surgery will be beneficial. 

Page last reviewed: 19/01/2015

Next review due: 19/01/2017