A guide for families. Enlarged vestibular aqueducts and childhood deafness

Transcription

1 A guide for families Enlarged vestibular aqueducts and childhood deafness

2 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.

3 Enlarged vestibular aqueducts and childhood deafness A guide for families 3 Page Contents 4 Introduction 5 Types of deafness 6 What are enlarged vestibular aqueducts? 7 What type of deafness do children with enlarged vestibular aqueducts have? 8 How are enlarged vestibular aqueducts diagnosed? 8 How common are enlarged vestibular aqueducts? 9 What causes enlarged vestibular aqueducts? 10 Audiological management 12 Do enlarged vestibular aqueducts cause any other difficulties? 13 How does having enlarged vestibular aqueducts affect hearing and balance? 14 Precautions and prevention 15 Considerations for the classroom 17 Where can I get further information or support? NDCS uses the word deaf to refer to all levels of hearing loss.

4 4 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.

5 Enlarged vestibular aqueducts and childhood deafness A guide for families 5 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.

6 6 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

7 Enlarged vestibular aqueducts and childhood deafness A guide for families 7 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.

8 8 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.

9 Enlarged vestibular aqueducts and childhood deafness A guide for families 9 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

10 10 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.

11 Enlarged vestibular aqueducts and childhood deafness A guide for families 11 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.

12 12 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.

13 Enlarged vestibular aqueducts and childhood deafness A guide for families 13 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.

14 14 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.

15 Enlarged vestibular aqueducts and childhood deafness A guide for families 15 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.

16 16 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.

17 Enlarged vestibular aqueducts and childhood deafness A guide for families 17 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 For information about Pendred syndrome, go to 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 USA 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.

18 18 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, City Road, London EC1V 1JN Tel: Fax: Freephone Helpline: or textphone: (Monday to Friday 9.30am 5pm) info@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. Yahoo group Large Vestibular Aqueduct Syndrome (LVAS) Online information and support group for people and parents of children who have LVAS.

19 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 A Freephone Helpline (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 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 updates. An online forum for parents and carers to share their experiences, at A website for deaf children and young people to get information, share their experiences and have fun

20 NDCS is the leading charity dedicated to creating a world without barriers for deaf children and young people. NDCS Freephone Helpline: (voice and text) helpline@ndcs.org.uk Published by the National Deaf Children s Society NDCS March Dufferin Street, London EC1Y 8UR Tel: (voice and text) Fax: NDCS is a registered charity in England and Wales no and in Scotland no. SC ISBN WEB This publication can be requested in large print, in Braille and on audio CD.