Download Enlarged vestibular aqueducts and childhood deafness

A guide for families
Enlarged vestibular aqueducts
and childhood deafness
Our vision is of a
world without barriers
for every deaf child.
Thank you
To Dr Lesley Batchelor, Consultant Community Paediatrician
(Audiology), Macclesfield District General Hospital, who allowed
us to use text from an existing leaflet, and to Dr Breege Mac Ardle,
Consultant in Audiovestibular Medicine, Nuffield Hearing & Speech
Centre, London. We are grateful for their advice and guidance in
producing this booklet.
Enlarged vestibular aqueducts and childhood deafness A guide for families
Page Contents
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Introduction
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Types of deafness
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What are enlarged vestibular aqueducts?
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What type of deafness do children with enlarged vestibular aqueducts have?
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How are enlarged vestibular aqueducts diagnosed?
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How common are enlarged vestibular aqueducts?
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What causes enlarged vestibular aqueducts?
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Audiological management
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How does having enlarged vestibular aqueducts affect hearing and balance?
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Precautions and prevention
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Where can I get further information or support?
Do enlarged vestibular aqueducts cause any other difficulties?
Considerations for the classroom
NDCS uses the word ‘deaf’ to refer to all levels of hearing loss.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
Introduction
This booklet has been written for families and aims to provide
the relevant information for all children with enlarged vestibular
aqueducts. 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.
It may be helpful to read this booklet alongside other NDCS
publications. Throughout the text the reader is referred to other
relevant information.
The name ‘enlarged vestibular aqueducts’ may be shortened and
known as EVA. They are also known as wide vestibular aqueducts,
dilated vestibular aqueducts, large vestibular aqueduct syndrome
(LVAS) or large endolymphatic duct and sac syndrome (LEDS). All
these terms relate to the same condition.
Enlarged vestibular aqueducts and childhood deafness A guide for families
Types of deafness
Conductive deafness happens when sound cannot pass efficiently
through the outer and middle ear to the cochlea and auditory nerve.
The most common type of conductive deafness in children is caused
by glue ear.
Sensori-neural (or nerve)
deafness is when there is a
fault in the inner ear (most
often because the hair cells in
the cochlea are not working
properly) or auditory
(hearing) nerve. Sensorineural deafness is permanent.
Children who have a sensorineural deafness can also
have a conductive deafness
such as glue ear. This is
known as mixed deafness.
For more information about
different types and levels of
deafness, and information
on hearing tests, read the
NDCS booklet Understanding
your Child’s Hearing Tests.
For more information about glue ear and various treatments available,
read the NDCS leaflet Glue Ear: A guide for parents.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
What are enlarged vestibular aqueducts?
The inner ear is located deep in a skull bone called the temporal bone.
The vestibular aqueduct is a tiny, bony canal located in the temporal
bone, which connects the inner ear to the brain cavity. The vestibular
aqueduct contains a fluid filled tube called the endolymphatic
duct and this connects the inner ear to the endolymphatic sac.
The endolymphatic duct and sac contain fluid called endolymph.
Endolymph has a unique chemical composition and is essential for
normal inner ear function.
In the early months of life the vestibular aqueduct is short and wide.
It is usually fully formed at around 3–4 years of age when it is narrow,
long and J-shaped. In children with enlarged vestibular aqueducts
their vestibular aqueducts have not fully formed. They remain short
and wide and, in turn, their endolymphatic duct and sac are larger than
usual. The enlarged vestibular aqueduct can occur just on one side
but often is seen on both sides.
Diagram of enlarged vestibular aqueducts
Thank you to the National Institute on Deafness and Other Communication
Disorders for providing this image
Enlarged vestibular aqueducts and childhood deafness A guide for families
What type of deafness do children with enlarged
vestibular aqueducts have?
Children with enlarged vestibular aqueducts will have a sensorineural deafness that usually affects both ears but can be unilateral
(affecting one side). Sensori-neural deafness is permanent and most
types of sensori-neural deafness are stable so that the hearing does
not usually change over time. However, some features of the deafness
related to enlarged vestibular aqueducts include:
• The deafness may develop around the time of birth, in the early
months or later in childhood
• The deafness may be progressive or gets worse over time
• The deafness may fluctuate or change over time
• Hearing fluctuations may happen following relatively minor head
trauma
• Deafness, or changes to the level of deafness, may happen suddenly
• There may be a conductive (middle ear) component to the deafness
which may not be the common glue ear type.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
How are enlarged vestibular aqueducts diagnosed?
Children with sensori-neural deafness may be offered a CT or MRI
scan. A CT scan will show the bony parts of the ear and the vestibular
aqueduct can be seen and measured. The vestibular aqueduct
is usually less than 1.5mm in width. An MRI scan will show the
soft tissues and fluids so the endolymphatic duct and sac may be
recognisable. A radiologist is a doctor who specialises in obtaining
and interpreting medical images, such as X-rays. It is important
that an experienced radiologist interprets the scan result as the
condition is unusual in the general population and it is easy to miss
abnormalities.
Enlarged vestibular aqueducts may also be associated with other
deformities or underdevelopment of the cochlea and/or the vestibular
(balance) organ and these will also be visible on the scan.
For further information on CT and MRI scans, as well as other medical
tests used to help identify the cause of deafness, read the NDCS
booklet Understanding your Child’s Hearing Tests.
How common are enlarged
vestibular aqueducts?
It is not known how common
enlarged vestibular aqueducts
are in the general population
but research suggests that most
children known to have enlarged
vestibular aqueducts will develop
deafness. Around one in 10
children with sensori-neural
deafness have enlarged vestibular
aqueducts.
Enlarged vestibular aqueducts and childhood deafness A guide for families
What causes enlarged vestibular aqueducts?
There are probably many causes of enlarged vestibular aqueducts but
at the moment we don’t know what they all are. These causes may be
genetic or environmental.
Enlarged vestibular aqueducts can occur alone or sometimes happen
as one part of a syndrome. ‘Syndrome’ is a medical term used to
describe a collection of symptoms or signs that doctors recognise as
commonly occurring together.
Enlarged vestibular aqueducts are often associated with other
structural abnormalities of the cochlea, meaning the cochlea did not
develop fully before birth. An example of a structural abnormality is
a ‘Mondini malformation’ (Mondini dysplasia) where the cochlea has
fewer than the usual two and a half turns that make up its typical
‘snail shell’ appearance. One piece of research suggested that half
the people with an abnormality in the inner ear had an enlarged
vestibular aqueduct.
In some children their enlarged vestibular aqueducts are caused by a
change or fault in the SLC26A4 gene and your doctor may offer a test
for this gene. Some changes in the SLC26A4 gene are non-syndromic
and not thought to cause any other medical problems. Other changes
to this gene may result in Pendred syndrome. According to a study
by the National Institute on Deafness and Other Communication
Disorders (NIDCD), approximately one-third of individuals with
enlarged vestibular aqueducts and deafness have Pendred syndrome.
All children with Pendred syndrome have enlarged vestibular aqueducts,
but not all children with enlarged vestibular aqueducts have Pendred
syndrome. Pendred syndrome is associated with enlargement of the
thyroid gland (goitre) which may not occur until puberty.
Another syndrome where enlarged vestibular aqueducts may be seen
is branchio-oto-renal (BOR) syndrome. A genetic alteration in the EYA1
gene causes BOR syndrome although there are other rarer genetic
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Enlarged vestibular aqueducts and childhood deafness A guide for families
causes as well. BOR syndrome is associated with abnormal kidney
development (small or different shape), outer ear changes (such as
small holes known as ‘pits’), skin tags or neck cysts and is usually
suspected clinically before the enlarged vestibular aqueducts are
noted on the scans.
For further information and support on Pendred syndrome and
branchio-oto-renal (BOR) syndrome, see the section ‘Where can I get
further information or support?’
For further information on the genetics of deafness, genetic testing
and genetic counselling, read the NDCS booklet Genetic Counselling:
Information for families.
Audiological management
All deaf children should be offered regular hearing tests. This is likely
to be at least every three months during the first year they wear
hearing aids, then six-monthly until the age of five years, with at least
annual tests over the age of five and until they leave school.
If you notice any changes in your child’s hearing levels in-between
appointments it is important to let your audiologist know. Sometimes
children with enlarged vestibular aqueducts will have sudden drops in
their hearing levels. The hearing may come back to its previous level, or
there may be some partial improvement to a new ‘normal’ level. Hearing
levels may therefore follow a gradual stepwise deterioration over time.
Hearing aids are used very effectively for deafness caused by
enlarged vestibular aqueducts. It is important that they are regularly
programmed to take account of any changes to the child’s hearing.
Some children with severe or profound hearing loss who do not benefit
fully from conventional hearing aids may benefit from cochlear implants.
For further information about hearing aids and cochlear implants, read the
NDCS booklets Hearing Aids: Information for families and Cochlear
Implants and Deaf Children: A guide for families.
Enlarged vestibular aqueducts and childhood deafness A guide for families
Glue ear is a very common childhood condition that can cause temporary
conductive deafness. A child with enlarged vestibular aqueducts may
also have glue ear that may make their hearing levels temporarily worse.
It is important that this is taken into account when programming their
hearing aids to ensure they are not disadvantaged during this time.
For further information on glue ear, testing for glue ear, its effects and
treatment options, read the NDCS leaflet Glue Ear.
Your local audiology and education services will provide support for
you and your child. Your audiologist will refer you to the education
authority’s specialist hearing impairment service (teacher of the
deaf ) who will be able to advise you on encouraging good early
communication, use of hearing aids, school placement and is
responsible for ensuring your child has any appropriate support
they need in school for their hearing. You may also be offered an
appointment with a speech and language therapist.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
Do enlarged vestibular aqueducts cause any other
difficulties?
In addition to deafness, enlarged vestibular aqueducts may also be
linked with balance problems (known as ‘vestibular dysfunction’).
Sometimes the semicircular canals (vestibular or balance organ)
are underdeveloped in a similar way to the cochlea. Some children
may experience a feeling of dizziness and imbalance, particularly
with minor head trauma; this may occur whether or not the blow has
affected their hearing. Other children may have very poor vestibular
function (vestibular hypofunction), which makes it difficult for them
to learn to do tasks that require balance such as sitting and walking.
However, the brain is very good at making up for a weak vestibular
system, and most children and adults with enlarged vestibular
aqueducts do not have a problem with their balance on a day-to-day
basis. Some do have problems with balance in certain situations such
as walking along uneven ground in the dark.
Balance function assessment,
safety advice and specialised
physiotherapy may be helpful for
children with balance problems
due to enlarged vestibular
aqueducts.
For further information on the
balance system, testing and
disorders, read the NDCS
factsheet Balance and Balance
Disorders.
Enlarged vestibular aqueducts and childhood deafness A guide for families
How does having enlarged vestibular aqueducts affect the
hearing and balance?
Doctors don’t know exactly
how having enlarged
vestibular aqueducts affects
the hearing and balance.
The most widely accepted
explanation is that rapid
fluctuations in pressure in
the fluids surrounding the
brain result in abnormal
transmission of these forces
through the enlarged
vestibular aqueduct. This in
turn causes pressure on the
delicate membranes of the
inner ear, leading to possible
damage to the tiny hair cells
which convert sound (in the
cochlea) or movement (in
the semicircular canals) into the electrical signals which the brain
uses to make sense of sound and movement. These changes in
intra-cranial pressure could be caused by head trauma such as a
knock to the head, strenuous exercise, vigorously playing woodwind
or brass instruments, or changes in barometric pressure such as flying
in unpressurised aircraft.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
Precautions and prevention
Not every child with enlarged vestibular aqueducts will have
fluctuating or sudden drops in hearing levels. Each child with this
condition will react in a different way to minor head trauma. The
hearing of some may be completely unaffected where another may
have dizziness, tinnitus and/or fluctuating hearing. Sometimes a child
may have no symptoms or apparent trigger other than sudden and
permanent deterioration of their hearing thresholds.
Parents need to make informed choices on behalf of young children,
carefully balancing up the need to try and avoid the risk of any
knocks to the head or changes in pressure with allowing children to
undertake normal childhood activities. Ultimately it is only possible to
know which triggers affect which children after they have taken place.
The general advice is therefore cautious even for children who have
previously not had any problems caused by head injury. Schools and
parents should always take decisions together on which sports and
activities children participate in during school time and this may vary
according to previous history of fluctuations in hearing.
It is advisable to avoid activities where risk of blows to the head
or increased pressure on the inner ear are inevitable or very likely,
including:
• contact sports, such as kick-boxing, boxing, ice-hockey and rugby
• scuba diving
• go-karting/quad biking
• snowboarding
• bumper cars/roller coasters
• weightlifting
• bungee jumping.
Enlarged vestibular aqueducts and childhood deafness A guide for families
When activities may result in a blow to the head but are not
considered inevitable then it may be appropriate to allow them with
the correct head protection (e.g. scrum caps, helmets, etc.):
• football, netball, hockey, squash
• cycling
• horse-riding
• sailing
• gymnastics.
Activities that are generally considered low-risk include:
• swimming
• snorkelling
• supervised bouncy castles and trampolining.
About a third of children with enlarged vestibular aqueducts
have such poor vestibular function that swimming underwater is
dangerous. These children can become disorientated under water
because they don’t know the right way up. All children with vestibular
hypofunction must always swim in the company of someone who
knows about their difficulties. If your child has poor balance you are
advised to discuss the issue with your doctor for advice about safety.
Considerations for the classroom
Below are some considerations that you may wish to think about
and discuss with your child’s teachers in order for your child to
receive the appropriate support. Remember that the support needs
of your child will depend greatly on previous history.
Pre-schoolers (for example in nurseries and playgroups)
• Depending on the degree of deafness and history, your child may
benefit from additional support in the group.
• Use of a classroom assistant may be helpful for guarding against
rough and tumble knocks.
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Enlarged vestibular aqueducts and childhood deafness A guide for families
Infants
• Depending on the degree of deafness and individual needs,
your child may benefit from additional support in the group.
• The need for a careful balance between the use of classroom
assistants for access to curriculum and for playground patrol.
• How much supervision you feel your child will need at break times.
• The need to mention if your child has an IEP (individual
education plan), statement of special educational needs or
coordinated support plan (in Scotland).
Juniors
• The need for a balance between your child’s emerging
independence and the need for caution in play fighting.
• How to encourage your child to take responsibility for their behaviour.
• How or whether your child can participate in sporting activities.This
may vary according to previous history of fluctuations in hearing.
Secondary
• How your child learns to take responsibility for not putting
themselves at risk, for example, by not sitting in a place where
there is an increased risk of getting hit on the head.
• When your child takes part in a sporting activity, whether using a
specialist helmet or head protection will be sufficient or if rules
need to be adapted.
• Whether or not your child should be discouraged from taking part
in activities that could be dangerous, such as driving a motorbike.
Enlarged vestibular aqueducts and childhood deafness A guide for families
Where can I get further information or support?
National Institute on Deafness and Other Communication
Disorders (NIDCD)
The NIDCD is one of the institutes that comprise the National
Institutes of Health (NIH). It is part of the United States Department
of Health and Human Services. The goal of NIH research is to acquire
new knowledge to help prevent, detect, diagnose and treat disease
and disability.
For information about enlarged vestibular aqueducts, go to
www.nidcd.nih.gov/health/hearing/eva
For information about Pendred syndrome, go to
www.nidcd.nih.gov/health/hearing/pendred
The Vestibular Disorders Association (VEDA)
VEDA is an American organisation that aims to serve people with
vestibular disorders by providing information, offering a support
network and elevating awareness of the challenges associated with
these disorders.
VEDA, PO Box 13305, Portland OR 97213 USA
www.vestibular.org/vestibular-disorders/specific-disorders/
enlarged-vest.-aqueduct.php
The Cain Foundation for Branchio-Oto-Renal Syndrome
The Cain Foundation is a voluntary health organisation based in
Australia that seeks to develop and rapidly apply the most promising
research to treat and cure those with branchio-oto-renal (BOR)
syndrome, educate both the public and medical practitioners and to
improve the health and well-being of individuals and families affected
by this syndrome.
www.thecainfoundation.com
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Enlarged vestibular aqueducts and childhood deafness A guide for families
Contact a Family
Contact a Family provides support, advice and information for families
with disabled children, no matter what their condition or disability.
Contact a Family, 209–211 City Road, London EC1V 1JN
Tel: 020 7608 8700
Fax: 020 7608 8701
Freephone Helpline: 0808 808 3555 or textphone: 0808 808 3556
(Monday to Friday 9.30am–5pm)
Email: [email protected]
www.cafamily.org.uk
Center for Hearing Loss Help
The Center for Hearing Loss Help aims to help people live successful
lives by providing information, help, support and selected quality
products to people with hearing loss, tinnitus and phantom sounds,
balance issues and other ear-related problems.
www.hearinglosshelp.com/articles/lvas.htm
Yahoo group – Large Vestibular Aqueduct Syndrome (LVAS)
Online information and support group for people and parents of
children who have LVAS.
http://health.groups.yahoo.com/group/LVAS
NDCS provides the following services through our membership scheme.
Registration is simple, fast and free to parents and carers of deaf children
and professionals working with them. Contact the Freephone Helpline
(see below) or register through www.ndcs.org.uk
• A Freephone Helpline 0808 800 8880 (voice and text) offering clear, balanced
information on many issues relating to childhood deafness, including
schooling and communication options.
• A range of publications for parents and professionals on areas such as
audiology, parenting and financial support.
• A website at www.ndcs.org.uk with regularly updated information on all
aspects of childhood deafness and access to all NDCS publications.
• A team of family officers who provide information and local support for
families of deaf children across the UK.
•
Specialist information, advice and support (including representation at
hearings if needed) from one of our appeals advisers in relation to the
following types of tribunal appeals: education (including disability
discrimination, special educational needs (SEN) and, in Scotland, Additional
Support for Learning (ASL)); and benefits.
• An audiologist and technology team to provide information about deafness
and equipment that may help deaf children.
• Technology Test Drive – an equipment loan service that enables deaf children
to try out equipment at home or school
• Family weekends and special events for families of deaf children.
• Sports, arts and outdoor activities for deaf children and young people.
• A quarterly magazine and regular email updates.
• An online forum for parents and carers to share their experiences, at www.ndcs.org.uk/parentplace.
• A website for deaf children and young people to get information, share their
experiences and have fun www.buzz.org.uk.
NDCS is the leading charity dedicated to creating
a world without barriers for deaf children and
young people.
NDCS Freephone Helpline:
0808 800 8880 (voice and text)
Email: [email protected]
www.ndcs.org.uk
Published by the National Deaf Children’s Society © NDCS March 2011
15 Dufferin Street, London EC1Y 8UR
Tel: 020 7490 8656 (voice and text) Fax: 020 7251 5020
NDCS is a registered charity in England and Wales no. 1016532 and
in Scotland no. SC040779. ISBN 978-1-907814-14-3 WEB
This publication can be requested in large print, in Braille and on audio CD.