Diagnosing_HI

Medical tests to diagnose a Hearing Loss

The process to find out why a child has a hearing loss is sometimes called an ‘aetiological investigation’.

The tests listed can help find the reason for a child’s hearing loss in 40% to 50% of cases. For the other 50% to 60% of cases it’s not possible to find out why a child has a hearing loss. Although this can be frustrating, it may be helpful for you to know what didn’t cause it.

Doctors may sometimes suggest tests on other parts of your child’s body, like the kidneys or heart, to help find out the cause or rule out conditions that can be associated with hearing loss. Hearing loss can be part of a syndrome, meaning a collection of symptoms or signs that commonly appear together. Although medical conditions associated with hearing loss are quite rare, it’s important to get this checked.

What happens when you see the doctor?

The doctor will take details of your child’s medical history. This will include questions about the pregnancy and the birth, including any medication that was taken during the pregnancy and the mother’s health before, during, and after the birth.

The doctor will ask you about your child’s immunisations (routine baby jabs). In toddlers and older children, the doctor will ask about your child’s development (including speech and language and milestones such as when your child was sitting, walking etc.). The doctor may also ask whether your child has:

  • had meningitis, mumps, measles or other illnesses
  • been exposed to loud noises
  • taken any prescribed medication
  • suffered any head injuries
  • had any ear infections
  • had sight problems
  • had balance problems.

The doctor will also ask about the hearing of other family members, on both sides of the family.

Physical examination

The doctor will look at your child’s head and face and may take some measurements. The doctor will also look at your child’s neck, skin, nails, arms, legs, chest, abdomen (tummy), eyes, mouth, palate (roof of the mouth) and ears. They are looking for any minor differences or signs (for example, tiny holes in the skin known as ‘pits’), that may help to diagnose the cause of your child’s hearing loss. The doctor will assess your child’s development in relation to the expected ages and developmental stages (see your baby’s personal child health record – the red book – for further information on this).

The doctor may ask close family members to have a hearing test, known as pure tone audiometry.

Imaging

Imaging is a term covering different ways of looking at parts inside the body (such as bones or major organs) and how they’re working.

The doctor uses an MRI (magnetic resonance imaging) scan or a CT (computerised tomography) scan to look at the structures of the ear and hearing nerve. Both types of scan are commonly used with children who have a hearing loss.

Electrocardiography (ECG)

An ECG is a recording of the rhythm and electrical activity of the heart. There’s a very rare syndrome (Jervell and Lange Nielsen syndrome) linking severe and profound hearing loss to a heart problem. If this heart problem is found, it can be treated.

Depending on your child’s and your family’s medical history, your doctor may advise an ECG for a small number of children with severe to profound hearing loss to help rule out this condition. There are no risks associated with having this test.

Blood and urine tests

Depending on your child’s and your family’s medical history, the doctor may ask for one or more routine blood and urine tests.These tests can help doctors to identify the cause of the hearing loss.

Ophthalmology (eye test)

All children learn from what they see and hear around them. Children who have a hearing loss rely on their eyesight even more than other children do. Up to 40% of children with sensorineural hearing loss also have an eye problem. This may just mean that the child will need to wear glasses when they are older, but an eye test can also help to diagnose a syndrome associated with hearing loss (Usher syndrome).

Genetic testing

Just as children inherit features such as hair colour or eye colour from their parents, sometimes hearing loss is inherited.

If your child’s hearing loss could have a genetic cause, you should be given the chance to discuss this with a trained genetics counsellor. Genetic counselling gives families information about:

  • the cause of a range of inherited conditions
  • how an inherited condition might affect the child and family in the future
  • how likely you are to have another child with the same condition.

Some families find it helpful to know whether the hearing loss and any other medical condition were inherited. Other families prefer to wait until their children are grown up and able to decide for themselves.

If you choose to proceed with a  genetic test, this will involve your child, and possibly other family members, having a blood test.

The blood sample will be used to look for the gene or genes known to be linked with hearing loss, for example, a gene known as Connexin 26. Not all the genes related to hearing loss have been identified and for most there is not yet a routine test. Other genetic causes of hearing loss are rarer, but new ways of testing many genes at once are becoming available. You will be able to discuss the testing options at a clinic appointment.

What next?

Some or all of the tests in this section will be offered to your child, not necessarily in the order given here. Your doctor will give you more information which will help you decide whether you want your child to have the tests, and the best time for these to be carried out. Test results that may offer immediate benefit to a baby are best done at an early stage, for example when the infection screen is carried out.

Most of the tests are not urgent and it’s important that you feel comfortable with your child having them. If you have any worries, you can talk about them with your doctor.


© Information courtesy of and adapted from the National Deaf Children’s Society Information Handbook Understanding your Child’s Hearing Tests

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