Balance and balance disorders

Transcription

1 Introduction This factsheet has been written for parents to provide information about the balance system and balance disorders. You may have been given this factsheet when balance tests are recommended. If you have any questions or concerns about your child s balance discuss them with your child s doctor. Balance problems can occur when the organ of balance does not work properly (vestibular hypofunction). Children can be born with this or acquire it with illness or trauma. With hypofunction development of balance function may be delayed and this might mean that babies and young children take longer to reach developmental milestones such as sitting unsupported and walking. Older children may have difficulties with certain activities such as learning to ride a bike. This is called imbalance. Other types of balance problem can give rise to dizziness or vertigo or episodes of unsteadiness. These can occur at any time in childhood. Throughout the factsheet we use the term your doctor which could be a paediatrician who specialises in audiology, an ear, nose and throat (ENT) consultant or an audiological physician. Contents How the balance system works Page 2 Why is the balance system tested? Page 3 How is the balance system tested? Page 3 Helping balance problems Page 5 Some conditions that may include balance problems Page 6 Useful organisations Page 7 More information Page 8 NDCS uses the word deaf to refer to all levels of hearing loss.

2 How the balance system works The inner ear consists of the cochlea, the vestibule and the semicircular canals. The cochlea is the organ of hearing and looks like a snail s shell. The organ of balance includes the vestibule and the semicircular canals. These structures are filled with fluid and have sense organs made up of small hair cells which detect movement and gravity. As we move in space these sense organs send information about our balance to the brain. As well as the vestibular system in the inner ear, the brain also uses information from two other systems to maintain balance: Visual information from the eyes tells the brain where we are in relation to the environment around us. For example, when we are walking our brain is receiving different visual information from our surroundings. Special pressure receptors in the legs and body, known as proprioceptors, send signals to the brain that tell it about posture and movement and also about the surrounding physical environment such as uneven or sloping ground. Information from these three systems is received and interpreted by the brain, which then sends back instructions to the muscles controlling our movement so that we are able to keep our balance. A temporary change or problem with one part of the system can result in temporary dizziness or unsteadiness, for example inner ear infection or glue ear. Sometimes the vestibular system is affected by injury, illness or a long-term condition, for example migraine. Sometimes the vestibular system and the cochlea have been affected by the same problem and so deafness and balance problems can occur together, for example meningitis, EVA, CHARGE and other syndromic causes of deafness. However, this is not always the case and many deaf children have excellent balance while dizzy children can have normal hearing.

3 Why is the balance system tested? Tests of the balance system can be done when: there is a history of dizziness there is some difficulty with balance A deaf child may also have balance tests when: there has been delay in learning to sit or walk the deafness is one-sided (unilateral) or a different level in each ear (asymmetrical) the level of deafness is changing a cochlear implant is being considered the cause of the deafness is being examined in detail The tests can: help to determine the cause of balance problems and/or dizziness give more information about the function of the inner ear may help find the cause of the child s deafness Even if a deaf child appears to have good balance it can still be useful to look more closely at their balance system. Children are clever at compensating for weaknesses in the balance system and it may not be obvious until full testing is done. Identification of balance problems can help your doctor understand more about your child and can sometimes help to understand the cause of the deafness. How is the balance system tested? Your child s doctor will carry out a clinical examination to assess your child s balance. These will include observation of some simple activities such as walking, marching on the spot and hopping on one foot, often with the eyes open and then closed. In very young babies an assessment of head control and muscle tone will give the doctor information about the child s balance system. Your child s doctor may recommend that a more detailed assessment of the balance is done. Some of the tests used in this assessment are described below. Your child s doctor will discuss which tests are planned and why they are recommended. A full balance assessment may last between 1½ to 3 hours. Preparation for the tests Balance tests are painless, but some of them may make your child feel unsteady, dizzy, or occasionally, sick. Most children do not have any trouble with testing and many even enjoy them. If your child does experience problems during testing, the tester will stop and give them a chance to recover. Some tests are carried out in the dark. If your child lip-reads or uses sign language it is important that they understand what will happen before the lights are turned off. One test may involve putting water into the ear canal and therefore the removal of any hearing aids.

4 Some medication/drugs can affect balance tests and you may be advised to stop using them before coming to the clinic. Alcohol can also affect results and young adults should not drink for 48 hours before testing. Balance Tests Balance tests rely on looking for and recording eye movements. Eye movements are recorded because there is an interaction between the eyes, eye muscles, and the vestibular system in the inner ear. These movements are called nystagmus. Nystagmus is an involuntary jerking of the eyes that occur when the balance system is stimulated. During everyday life nystagmus is not usually seen but it can be induced by certain movements or stimulating the vestibular system. Measuring nystagmus helps to determine the origin of the dizziness. Video-Nystagmography (VNG) The VNG measures movement of the eyes using special goggles. Your child will wear these goggles in a darkened room while their eye movements are recorded. Electronystagmogram (ENG) The ENG records eye movements using small stickers called electrodes, which are placed on the skin around the eyes. These electrodes pick up changes in the electricity within the eye as it moves. With both VNG and ENG your child will have eye movements recorded while they watch a bright light or a striped curtain (saccades, gaze testing, smooth pursuit tracking and optokinetic testing). In addition your child may be tested when sitting in a computercontrolled chair that rotates gently back and forth or round and round (sinusoidal and impulsive rotation). Very young children may be tested sitting on their parent s lap. Most of these tests are performed in a very dark room. Calorics Caloric testing is performed using either VNG or ENG recordings. A small earpiece is placed at the entrance of the ear canal and through this warm and/or cool water is washed into the outer ear for about 30 seconds. The water is a few degrees above or below body temperature. The temperature change caused by the water stimulates a response from the balance system. Eye movements are measured to record this response. Caloric testing is not painful, but may make your child feel lightheaded or dizzy for a short time. Posturography Your child will stand barefoot on a platform that measures how much they sway. The platform moves back and forth during the test and records how well they keep their balance. Your child will be wearing a safety harness so that they cannot fall.

5 Vestibular evoked myogenic potentials (VEMP) VEMP are used to measure the function of the sense organs of the vestibule. Small sticky electrodes are placed on the muscles of the neck and a sound is played into the ear. The sound waves stimulate the balance sense organ and the resultant change in tension of the muscle in the neck is measured. This is painless. This test is uncommon. Helping balance problems Dizziness or vertigo Some causes of dizziness are self-limiting and the child recovers quickly without the need for specific help. However children who develop recurrent or persistent dizziness often need quite specific help. Depending on the cause this may involve medication, physiotherapy exercises, occupational therapy or psychology. Your child s doctor will advise if these are necessary. Imbalance If a child is born with or acquires a balance problem early in life it is likely that they will develop ways of compensating quite naturally without the need for any special help or therapy. However it will be helpful to know that there are weaknesses in their system so that simple steps can be taken to help if necessary. For example, a child may manage extremely well during the day but have difficulty walking in a straight line in the dark. It might be helpful for this child to have a night light in hallways in case they need to get up at night to prevent them bumping into doorways etc. It is unlikely that a balance problem will prevent a child from doing normal childhood activities but it is also important to know if there are any safety precautions to be aware of. For example, ensuring that children are closely supervised when swimming in case they become disorientated underwater, and giving children extra time and support when learning to ride a bike. Some conditions that may include balance problems Benign paroxysmal vertigo of childhood (BPVC) is characterised by brief episodes of vertigo and nausea with no change in hearing or loss of consciousness. Children may also be sick. This sometimes, but not often, happens when children get migraine. For more information about migraine in children go the and type migraine in children into the search box. The Migraine Action Association also hosts a website for children and teenagers at For further information about migraine contact The Migraine Association (details can be found in the Useful Organisations section at the end of this factsheet). CHARGE syndrome is a congenital (born with) condition affecting about one in 10,000 births. The condition affects several areas of the body and development. The acronym CHARGE reflects the involvement of Coloboma (a hole in one of the structures of the eye), Heart defects, Atresia choanae (blockage of the nasal passages), Restricted growth and development, Genital hypoplasia and Ear anomalies. For further information about CHARGE contact Contact a Family (details can be found in the Useful Organisations section at the end of this factsheet).

6 Diabetes. There are a number of very rare forms of diabetes that may be associated with deafness. Some of these are genetic (inherited) disorders of the mitochondria (small organelles within the body s cells that play a critical role in energy production). Mitochondrial DNA is inherited only from the mother and cells that are especially vulnerable to any defect of this sort may be damaged. DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy and Deafness) or Wolfram's Syndrome is one of these. For further information go to Children with Diabetes website at Enlarged Vestibular Aqueduct (EVA) is a congenital (born-with) condition that can cause progressive or fluctuating deafness. Some children also experience a feeling of dizziness and imbalance, and a general lack of co-ordination. EVA is sometimes known as wide vestibular aqueduct or large vestibular aqueduct. Children with Pendred syndrome have an EVA but not all children with EVA have Pendred syndrome. See below for more information on Pendred syndrome. For more information on EVA read the NDCS Enlarged Vestibular Aqueducts publication. Glue ear is a very common childhood condition. It is caused by is a temporary build-up of fluid blocking the middle ear that makes it harder for sound to pass through to the inner ear. This can make quieter sounds difficult to hear. Sometimes glue ear can also affect a child s behaviour, for example becoming tired and frustrated, poor concentration and preferring to play alone. Some parents also notice that their child has more problems with their balance or become clumsy whilst they have glue ear. For more information on glue ear read the NDCS Glue Ear leaflet. Jervell and Länge-Nielsen or Long QT syndrome is a congenital (born with) condition that may be genetic (inherited). Jervell and Länge-Nielsen syndrome is characterized by deafness and abnormality of the heart rhythm that may cause fainting or be life threatening. Profoundly deaf children should be offered an ECG to help rule out the condition as a cause for their deafness. If the condition is diagnosed most people with the condition respond well to medication or other treatment. For further information about Jervell and Länge-Nielsen or Long QT syndrome contact Contact a Family (details can be found in the Useful Organisations section at the end of this factsheet). Meningitis is inflammation of the meninges, the lining that surrounds the brain. This is usually caused by bacterial and viral infections. Meningitis can cause hearing loss in a number of ways. The most common cause is the infection spreading into the inner ear. This can damage the cochlea in the inner ear. Another possible cause is inflammation of the auditory nerve, the nerve that carries sound signals to the brain. For more information on meningitis, phone the Meningitis Trust helpline on or visit their website at For more information on meningitis and deafness read the NDCS Meningitis and childhood deafness leaflet. Pendred syndrome is a genetic (inherited) condition. Pendred syndrome causes progressive deafness (becoming worse over time) as well as affecting the thyroid gland and sometimes a child s balance. The deafness in Pendred syndrome is caused by enlarged vestibular aqueducts (see EVA for more information). For more information on Pendred syndrome go to the National Institute on Deafness and Other Communication Disorders website at

7 Usher syndrome is a genetic (inherited) condition which affects around 3% to 6% of those children in the UK who are born with a hearing loss. During mid- to latechildhood, children with Usher syndrome start to have sight problems caused by a form of retinitis pigmentosa. The retina slowly loses its ability to send pictures to the brain. The early symptoms include difficulty seeing in the dark and in different lighting conditions. Over time, the field of vision gradually deteriorates until tunnel vision develops. For further information about Usher Syndrome contact Sense (details can be found in the Useful Organisations section at the end of this factsheet). Waardenburg syndrome is a genetic (inherited) condition. The common features of the syndrome can be deafness associated with wide spacing between the eyes, broadening of the bridge of the nose, different coloured eyes or a different coloured segment in one or both eyes and sometimes a distinctive white forelock of hair present above their forehead. Some people with Waardenburg syndrome are reported to have problems with balance as a result of the vestibular system being affected. Useful organisations Contact a Family is the only UK-wide charity providing advice, information and support to the parents of all disabled children - no matter what their disability or health condition. They enable parents to get in contact with other families, both on a local and national basis. They offer a range of services to support families including a freephone helpline and a number of offices, staff and volunteers around the UK. They provide information to professionals and developmental advice to support groups. They also work to influence services and have campaigns that aim to improve the quality of life for families with disabled children City Road London EC1V 1JN Phone: Fax: Helpline or Textphone Freephone for parents and families (Mon-Fri, 10am-4pm) helpline@cafamily.org.uk Sense is a national charity that supports and campaigns on behalf of children and adults who are deafblind. They provide specialist information, advice and services to deafblind people, their families, carers and the professionals who work with them. They also support people who have sensory impairments (deafness or blindness) and other disabilities. 101 Pentonville Road London N1 9LG Telephone: Textphone: Fax: info@sense.org.uk Website:

8 SENSE also has offices in Scotland, Wales and Northern Ireland, and regional offices in England. The Migraine Action Association is a charity, which helps people to understand what migraine is, how it can affect your life and the lives of those around you such as your family and friends. They also try to help people find ways to get better. They raise money for more research into what causes migraine and finding new treatments for special clinics where people with migraine can be treated by expert doctors and nurses. 27 East Street Leicester LE1 6NB enquiries@migraine4kids.org.uk More information If you are interested in finding out about or your child is already undergoing tests to try and establish the cause of their deafness you may like to read the NDCS publication Understanding your child s hearing tests which explains the different tests available. If you have been referred for genetic counselling or testing or you already know that your child has a genetic condition you may like to read the NDCS publication Genetic Counselling. All the publications mentioned in this factsheet are available to download from the NDCS website at For hard copies of any of the NDCS publications or information and practical support on issues related to your child s deafness, contact the NDCS Freephone Helpline on , us at helpline@ndcs.org.uk or contact us via Live Chat at If you prefer to speak a language other than English, tell us the language of your choice and your phone number (in English). We will call you back with an interpreter within a few minutes. Thanks We would like to thank Dr Katherine Harrup-Griffiths who provided some of the text from an existing leaflet, as well as all the professionals who commented on the contents of this factsheet. This information can be requested in large print, audio CD and in Braille. March 2008