Causes of deafness

There may be a number of possible reasons why your child is deaf, or the cause may be unknown. We have information on some of the most common causes of deafness in children and other related conditions, plus links to our information resources for more detail on each.

For information on exploring why your child might have a hearing loss, visit our Understanding childhood deafness webpage.

For information on genetic counselling, download our free resource Genetic Counselling - Information for Families

Auditory Neuropathy Spectrum Disorder (ANSD)

Cover page: Auditory Neuropathy Spectrum Disorder guide (credit: NDCS)

Auditory Neuropathy Spectrum Disorder (ANSD) occurs when sounds are received normally by the cochlea, but become disrupted as they travel to the brain.

Children with ANSD are likely to have greater difficulty understanding speech and distinguishing one sound from another than a child with a similar level of hearing, especially in the presence of background noise. The term ‘spectrum disorder’ helps with the understanding that ANSD affects children in different ways, with symptoms ranging from very mild to very severe.

Our resource is for families who have a child diagnosed with Auditory Neuropathy Spectrum Disorder. It is also relevant for professionals.

Download: Auditory Neuropathy Spectrum Disorder

To Parents From Parents

Following a study carried out by the University of Manchester we produced Auditory Neuropathy Spectrum Disorder, To Parents from Parents. In the study we talked to 21 families who had a child identified with auditory neuropathy spectrum disorder through the Newborn Hearing Screening Programme.

The families had used a range of options for their children, mainly including hearing aids, cochlear implants and sign language. Although parents and children experienced a range of outcomes, there were many common themes.
The resource describes what the families told us about their experiences and shares the useful advice which these parents would give to families who are in a similar position in the future.

Download: Auditory Neuropathy Spectrum Disorder: To Parents From Parents

Research in understanding parents needs following diagnosis of auditory neuropathy or dys-synchrony

We funded research carried out by Manchester University looking at the experiences of parents of children diagnosed with auditory neuropathy / auditory dys-synchrony. The researchers talked to families to find out what support they have had and how well it has worked for them and their children. We would like to thank all the families who agreed to take part in this research.

Download: Auditory Neuropathy Spectrum Disorder in Infants

Find out about other families' experiences of the condition.



Cholesteatoma is a cyst or pouch of skin within the ear. It is usually due to a repeated ear infection, which causes skin to grow inwards from the eardrum. The first sign may be a persistent smelly discharge from the ear. If left untreated, it can get bigger and destroy the delicate bones within the middle ear and cause permanent deafness.

It is necessary to remove the cholesteatoma before it can cause damage. If children have a chronic discharge from the ear over a long period it is very important that they see an Ear, Nose and Throat (ENT) specialist for assessment and advice. An ENT doctor can usually diagnose cholesteatoma by examining the ear.

More information

The following information may be useful for parents of children with cholesteatoma.

The following organisations offer more information for patients on cholesteatoma.


Cleft palate

Cleft palate or cleft lip and palate can affect many different functions, including speech and hearing. Our webpage for parents explains what cleft lip and cleft palate is, the type of deafness commonly associated with cleft palate, and how the deafness can be managed.

Read our webpage on cleft palate and deafness


Cytomegalovirus (CMV)

Photo of Christian helping Isabelle climb a tree

What is cytomegalovirus (CMV)?

CMV belongs to the herpes virus family. It is very common, affecting people all over the world. Despite there being very little public awareness, CMV is more common than many other conditions such as Down’s syndrome, spina bifida, toxoplasmosis and cystic fibrosis. Many of us will have had CMV by the time we are 40 years old. Sometimes CMV can cause cold or flu-like symptoms but often the infection has no symptoms so we may not know we have had it.

Once infected by CMV, the virus usually stays in an inactive form in the body (often for life). If your immune system becomes weakened the virus can reactivate but does not cause as much harm as the primary infection.

The CMV infection can cause illness in anyone with a weak immune system, such as an unborn baby. CMV infection in an unborn baby is called congenital CMV (congenital means present from birth). Congenital CMV (cCMV) causes about 10% to 20% of permanent deafness in children in the UK and is the leading cause of non-hereditary deafness. There is currently no vaccine to prevent cCMV, but researchers are working on one.

If you have the CMV infection as a child or adult, this is called 'acquired CMV'. If a baby has a CMV infection in the first month of life, this is called 'perinatal CMV'. Acquired and perinatal CMV are not known to cause childhood deafness.

How is CMV spread?

From one person to another through close contact with bodily fluids such as urine, saliva, blood, tears, breast milk, semen, vaginal fluids and faeces (poo). You cannot catch CMV from being in the same room as a person who has the infection. CMV can also be spread through transplants and transfusions through a donor with either an active or past infection. Patients receiving transplants or transfusions are more susceptible because of their weakened immune systems.

A pregnant mother infected with the CMV virus for the first time can transmit it across the placenta to her unborn baby. The majority of these babies will not have any problems.

When might deafness happen?

Half of all children with deafness caused by cCMV have a degree of deafness at birth and this may be picked up following newborn hearing screening. The other half go on to develop deafness after birth and will have had no problems identified on their newborn hearing screen.

Most deafness caused by cCMV develops during the first three years of life and so may affect speech and language development. Some children born with cCMV may develop deafness later in childhood. It is important that children with cCMV have regular hearing tests so that any changes in hearing are picked up early and help is offered quickly.

What type of deafness does cCMV cause?

cCMV causes sensori-neural deafness, which affects the cochlea. This is the organ in the inner ear that changes sound vibrations into nerve impulses to be sent to the brain – or the hearing nerve from the inner ear to the brain. This type of deafness is permanent and can affect one or both ears. Half of the children whose deafness is caused by cCMV will have progressive or late onset deafness (becoming worse over time).

cCMV may cause unilateral deafness (deafness in one ear). This is more common in children with asymptomatic cCMV, and some may develop deafness in the other ear later. Sometimes a child’s hearing may go up and down (fluctuate). Research is being carried out to try to understand how CMV affects hearing and how this damage might be prevented.

cCMV may also affect the balance organs in a child’s inner ear, their hearing nerve, or more rarely their ability to interpret sound (auditory processing disorder (APD)). Children with cCMV may also experience glue ear, which causes temporary conductive deafness. For further information visit our webpage on Glue ear.

For more information on symptoms of cCMV, how it’s diagnosed, treatment (including audiological care), precautions and prevention download our factsheet.

Download:  Congenital cytomegalovirus and deafness

More information

  • CMV Action
0845 467 9590


Enlarged vestibular aqueducts

Front cover image (credit: NDCS)

This resource is for families who have a child diagnosed with enlarged vestibular aqueducts. It may also be useful for professionals.

Download: Enlarged vestibular aqueducts and childhood deafness

It includes information on how enlarged vestibular aqueducts are diagnosed, what type of deafness they cause, audiological management, recommended precautions, and sources of other help and support.

More information


Glue ear

Glue ear is one of the most common childhood conditions. It is usually linked with ear infections and temporary, but long-term glue ear can affect children's hearing, speech development, and cause them to fall behind at school.

Read our webpage on glue ear.




Front cover of the Meningitis and Childhood Deafness booklet. (credit: NDCS)

Deafness is the most common after-effect of meningitis. Approximately one in ten children who survive meningitis develops deafness as a result of the illness.

This resource is for families who have a child who has become deaf through meningitis.  

Download: Meningitis and Childhood Deafness

It provides information on the hearing tests that are carried out following meningitis, the effects of any deafness, what can be done to help and the support that is available. This information may also be helpful to mainstream teachers who have children with deafness following meningitis in their class.

Watch our video with teenager, Dan, who talks about losing his hearing through meningitis.

Dan, who has been through meningitis, holds a football.

More information
Meningitis Now

Freephone 24-hour Helpline: 0808 80 10 388


Microtia and atresia

A girl with microtia with her mum.

Microtia guide (credit: NDCS)

What are microtia and atresia?

Microtia is a term used to describe under-development of the outer ear (pinna). It can vary from quite minor changes (such as the ear being smaller than expected) to ‘classic microtia’ where the pinna is missing. Classic microtia is often associated with absence of the ear canal – known as atresia. This is because the baby’s outer ear and ear canal develop together during pregnancy. In some cases the ear canal can look present from outside but ends at a ‘blind alley’ inside.

Types of microtia

Lobular type microtia: the outer ear is present but small and under-developed (peanut shaped). This is the most common type of microtia.

Conchal type microtia: the child has an ear canal although it may be very narrow (canal stenosis) or a blind ending with no eardrum. The outer ear is present and has a conchal bowl (middle part of the ear cartilage) but it is much smaller than normal. The upper part is often underdeveloped.

Small conchal type: the ear is smaller than usual but the key features of the outer ear are present, although they may have small differences in shape or form, such as a small conchal bowl. The ear canal is either missing (atresia) or has a narrow and blind ending.

Microtia happens more often in boys than in girls. It usually affects one side, and is known as unilateral microtia. It more often affects the right ear than the left.  About one in 10 children are affected on both sides – this is known as bilateral microtia.

What is the cause of microtia and atresia?

Microtia or atresia happens when the outer part of the ear does not develop fully during the early stages of pregnancy. The exact reasons for isolated (or non-syndromic) microtia or atresia remain unclear although it is usually a random, one-off event. It is not caused by anything the mother did wrong before or during the pregnancy. Medical research has suggested that sometimes certain prescribed medications taken during pregnancy, or genetic and/or environmental factors may be involved. Associated factors will be explored at the first meeting with your specialist multidisciplinary team (healthcare professionals with specialised skills and expertise). 

Microtia and deafness

There are different types of deafness – conductive, sensori-neural, unilateral or mixed – that can be associated with microtia and atresia, depending on which part of the ear is not formed or working as it should.

For more information on microtia and atresia including managing deafness caused by microtia and atresia, hearing devices, surgery and other medical conditions associated with microtia, download Children with microtia and atresia.

 Girl with microtia sits with her mum as she adjusts her BAHA.

More information

Microtia UK

Online only support group for families and adults affected by unilateral and bilateral microtia.



This condition affects the stapes, (the smallest bone in the body) found in the middle ear. Although it is known to mainly affect the middle ear, the condition can move to the rest of the inner ear. Sound enters the ear and reaches the eardrum, causing the small bones of the middle ear, the ossicles, to vibrate. The stapes transmits these vibrations to the inner ear. In otosclerosis, the stapes becomes fixed from an abnormal growth/overgrowth of bone which in turn causes conductive deafness.

Otosclerosis can be an hereditary disorder, but in many cases where there is no family history, it is thought to be caused by a virus. Otosclerosis usually develops between the ages of 15 to 35 but rarely has been known to occur in younger children.

Treatment may involve surgery i.e. a stapedectomy or you may prefer for your child to be fitted with a hearing aid. A stapedectomy involves replacing the stapes with a prosthetic device.  

More information



Genetic syndromes associated with hearing loss

Our webpage Genetic conditions associated with hearing loss lists the most common conditions which can cause or are associated with childhood deafness.

For example 10% to 15% of children with Down's syndrome have a sensori-neaural hearing loss and about 60% to 70% have a conductive deafness caused by glue ear.

Our Down's syndrome and childhood deafness webpage has information for parents of a child with Down's syndrome and explains how hearing loss can be managed.