Episode Transcript
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SA: Hello, and welcome to Practicing Paediatrics. In this series, we'll be showcasing the specialist work of the clinical staff here at Great Ormond Street Hospital. There are over 60 different clinical specialties at GOSH, providing tertiary and quaternary level care for many rare conditions. So if you are hoping to learn a little bit more about a unique condition or intervention, or just find out more about the advances at GOSH, this may be the series for you.
MAT: Hello and welcome. My name is Maria Athina Tsitsika and I'm currently a clinical fellow in audio vestibular medicine at GOSH. In this podcast, we joined Dr. Surangi Mendes, who is a newly appointed consultant in audio vestibular medicine, but who recently finished her training at GOSH, where she saw a range of children presenting with paediatric vestibular disorders.
In this episode, we will be covering definition used in vestibular medicine and looking at the relevant anatomy and physiology, which is related to balance. We will look at the two main categories of vestibular dysfunction in children. There are those with reduced functioning of the vestibular organ on one or both sides, known as vestibular hypofunction, and those who experience episodic dizziness.
We will also discuss how vestibular testing is undertaken, and round up with a brief glimpse into the principles of treatment.
Thank you so much, Surangi, for joining us on this podcast, and welcome. Shall we start by asking you, what would you like our listeners to get out of this podcast today?
SM: Hi Mara, thank you so much for asking me to join you. I'm really glad to be here. I suppose what we really want to get across is that balance problems and dizziness presenting in children is thought to be rare, but actually the overall prevalence in the paediatric population is around 5%, so it's not really that uncommon.
But dizziness, vertigo and balance problems are symptoms that can worry clinicians sometimes, as I think it's fair to say that it's not usually a topic that's extensively taught at medical school, particularly in relation to children. So I just wanted to give everyone a flavour of the sorts of problems that can present in a paediatric balance clinic and how one might approach a child presenting this way if they present in a generalised setting such as paediatric outpatients.
MAT: So our first question relates to some of the definition used in vestibular medicine. I think we really need to be clear on the terminology we are using, as of course the words dizziness, vertigo and unsteadiness can mean different things to non balanced specialists. So could you please go through those three terms for us?
SM: Sure. Yes. I mean, this is super important, particularly in relation to children, as you've got the added complexity, because they themselves might not be able to provide the history if they're very small. Or even if they can and the child is older, they might not really have the words to articulate these really difficult to describe symptoms properly. I mean, most adults find it really hard to describe these feelings. So I'll go through all these three.
So first of all, vertigo. By definition, this is an illusion of movement, usually a spinning or rotation of the child or their surroundings in the absence of any actual physical movement. You can ask the child what they feel, and if they recall the feeling, you might be surprised at what they're able to describe and remember. They might describe everything moving, or the house was turning, for example. Or you could give a suggested analogy. Was it like a spinning ride at a park, for example? Alternatively, you could give them a piece of paper and some pencils and ask them to draw what they felt. We've had kids before in our clinic draw in really large circular motions. So that gives us a pretty good idea of what's going on. But more often than not, you're relying on the parent or carer's description of what actually happened. Children with vertigo often look frightened, they might suddenly look pale and cling to a nearby adult or drop to the floor to attempt to try to hold on to what they perceive is moving around them. The description of these events is key. If rotation or spinning is described, this is suggestive of vestibular pathology most of the time.
Whereas dizziness is usually referred to as a sensation of lightheadedness and can be more of a non specific term. Again, ask the child to describe what they feel in a child friendly way. For example, does it feel like cotton wool in the head?
Unsteadiness is the correct description of what we used to call imbalance. It's the preferred way to describe the term postural instability, for example when standing or walking, rather than imbalance or the more ambiguous term of disequilibrium. If the unsteadiness is permanent, and present since early childhood, this can arise due to reduced function of vestibular organs in the inner ear, either the right or the left, or both, usually both, particularly if there are also delayed motor milestones. Parents might describe this to look like a drunk like walk or a waddle. And they may have a broad base gait to try to shift their centre of gravity. Or they might report frequent falls. They might have difficulty participating in PE or riding a bike, for example. Children are naturally very active, compared to adults anyway, so just asking about their usual activities will usually give some clues if they're having difficulties in relation to steadying their balance specifically.
If children have reduced balance function on both sides, they might specifically describe difficulty walking in the dark because they're more reliant on their vision specifically for balance, rather than the vestibular inputs from the inner ear, and they can have difficulty walking on uneven surfaces.
Similarly, when their proprioception is challenged on top of their vestibular inputs being low, this is challenging.
MAT: And what kind of questions should we be asking in terms of history taking?
SM: Yeah, so this is a really good question. So if you already have a description of the symptom, as we've discussed, just now, you want to ensure you've also got a good timeline of events next. Go back to the very start. Get the child or parent to describe the very first episode. What were they doing at that time? What was the environment like? Had they been travelling? What other important life events were happening at that time?
Then, were there any associated symptoms such as nausea, vomiting, light sensitivity, hearing loss, tinnitus, ear specific symptoms like ear pain or discharge? Or triggers such as loud sounds or head movements or lying in specific conditions, lack of sleep or stress causing these symptoms.
Then you need to try to work out the pattern of the presentation. Are the symptoms constant or are they episodic? Do they come and go? Was it just a one off event? All of these things can give you clues. If there are headaches, be sure to also take a thorough headache history. Ensuring you ask about the standard red flags as well. For example, symptoms of raised intracranial pressure, or new onset neurological symptoms, for example.
And then you have to go through the rest of the standard history taking, looking at medications, past medical history, family history, and the psychosocial setup for these children. All of these help pinpoint the diagnosis, as of course, as we know, the history is key with all areas of medicine.
MAT: And we appreciate this is really quite tricky to convey through a podcast without any visual aids but could you also give our listeners an overview of the relevant anatomy and physiology of the vestibular system, please? We know ENT does not feature as heavily in the UK medical school curriculum as we'd like it to.
SM: Yes, I can try. It is obviously difficult as you say without any visual aids, but we can try.
So there are two inner ear structures. There's the hearing organ, the cochlea, And then the vestibular organ, which is anatomically very close by. One on the right and one on the left. Each of the vestibular organs is made up of five components. There are three semicircular canals, which sense angular acceleration, and two otoliths, known as the utricle and saccule, which detect linear motion.
These vestibular structures provide inputs to the brain, along with visual input from the eyes, and proprioceptive input from the muscles and joints to allow a child to control their balance and achieve postural stability.
Now, anyone who's interested in balance and the vestibular system may have heard of the vestibular ocular reflex, which is abbreviated to the VOR. This is a very fast reflex that's super important to us as audio vestibular doctors. It exists between the vestibular organs, the eyes, and the eye movement nuclei in the brainstem. It serves to stabilize gaze by countering quick movements of the head. So, for example, when we make a head movement, our eye muscles are triggered instantly to create an eye movement opposite to that of our head movement at exactly the same speed to readjust the visual world, which in turn stabilizes the retinal image by keeping the eye still in space and focused on an object despite the head movement.
This reflex keeps us steady and balanced even though our eyes and head are continuously moving when we perform most actions. Therefore, if it's interrupted for any reason, this in itself can be a cause of steadiness, unsteadiness, and poor balance.
MAT: So what kind of things can go wrong with the vestibular system? How does a child with vestibular impairment present?
SM: So, yeah, this is a good question. There are two main presentations in the paediatric balance clinic. There's the child who's unsteady due to either one sided vestibular reduced function or complete loss, and that could also be affecting both sides. And there's also the child who has episodic dizziness and, or vertigo. That's a really loose generalisation but it's a good place to start usually. I think it's beyond the remit of this chat to go through a complete list of differentials for both of these presentations, but it's worth discussing some common causes.
So for the child presenting with episodes of dizziness or vertigo, the commonest cause, statistically, is migraine and its variants that can present in childhood. So I think most clinicians are familiar with the presentation of standard classical migraine headaches, but if vestibular symptoms coexist with these headaches, this can be due to a vestibular variant known as vestibular migraine.
Other variants of migraine in childhood include recurrent vertigo of childhood, cyclical vomiting, and abdominal migraine. It's also thought that paroxysmal torticollis and even infantile colic can, in some people, be forms of migraine variants. Other important causes of dizziness in children not to miss include an acute vestibulopathy, when the function of the vestibular organ is reduced on one side due to, for example, infection, and we call this vestibuloneuritis.
If there is associated hearing loss, then this is labyrinthitis. And things that are common in adults tend to actually be less prevalent in children, such as BPPV, benign paroxysmal positional vertigo, and Meniere's disease. These can occur in children, but are very, very rare. And remember, dizziness doesn't always arise due to vestibular pathology.
POTS and other causes, such as cardiac structural problems and conduction problems, can cause dizziness. Problems with the eyes can also cause dizziness such as squints and even uncorrected standard refractive errors. And also there are neurological causes. Psychological distress can also cause dizziness. For example, anxiety and panic attacks.
And for a child presenting with unsteadiness, there's a quite a wide differential. But if this has been present from birth with delayed motor milestones, as we touched upon before, this could be associated with vestibular cochlear structural abnormalities, such as aplasia of the vestibular structures.
Or these abnormalities may form part of a syndrome, for example, CHARGE syndrome, Pendred, or Usher syndromes. Another cause could be resulting from medication use. And the two big groups of medication we need to think about in children are antibiotics, specifically the aminoglycosides gentamicin, tobramycin, amikacin, and then in our oncology patients, cisplatin or carboplatin based chemotherapy can also cause autotoxicity. So that's just an overview of causes. Clearly there are more, but those are the big ones I think to be aware of.
So, just to kind of recap on that, there's two main presentations, bilateral or unilateral vestibular hypofunction and episodic dizziness.
MAT: And what is the difference between the vestibular presentations in children versus adults? Do adults with vestibular problems have the same type of diagnosis?
SM: So, I think the main thing to remember, and this is emphasised throughout our training in audio vestibular medicine, is that children are not just mini adults. You can't really just translate what you do and how you investigate adults to the paediatric population. Children present differently, they usually describe their symptoms differently to adults as we've discussed. The investigations tend to be much more comprehensive purely because you might just have less to work with in terms of the history because a child may not be able to describe their symptoms accurately as we touched upon. So you have to probably need to be more comprehensive in terms of the examination and investigations and they're certainly treated differently compared to adults as I think we're going to discuss shortly. So the big headline is that, the most common cause of paediatric episodic dizziness is migraine and its variants, and that can arise with vestibular presentations. And the most common cause of unsteadiness, presenting to our specialist vestibular clinics anyway, arises due to structural abnormalities or syndromic presentations. Whereas in adults, the commonest cause of episodic vertigo, particularly presenting in generalist settings, is benign paroxysmal positional vertigo, BPPV.
And there's also vestibular neuritis, as we touched upon before, which is inflammation usually due to viral infection of the vestibular nerve. Vestibular migraine is actually also very common in adults. And bilateral vestibular loss is clearly less likely to occur in adults due to structural problems. When this presents later in life, it might be due to exposure to ototoxic medications, meningitis or autoimmune disease or various other causes.
MAT: So for non vestibular specialists who are listening in, how and when can we refer children for balance testing? We know that access to specialist testing is limited and testing , facilities for vestibular problem is not available everywhere in this country.
SM: Yes, thanks for asking that. This is quite tricky actually, as access to specialist vestibular test centres is limited geographically. But, audio vestibular test centres do exist, and they have good facilities to be able to conduct a range of tests that assess the five different components of the vestibular organs, and also their central pathways.
So who should be referred? I think anyone with recurrent dizziness, vertigo or unsteadiness that cannot be explained after initial exploration and basic examination should be referred. Also, anyone with vestibular symptoms who also has hearing loss, any child with unexplained falls, and any child who has delayed motor milestones without any other explanation. These are the big ones. And the usual referral route would be for a child to be referred from primary care to a general paediatric clinic and then referred onwards to us. But if any of these features are present, then we really should be seeing them in a specialist paediatric dizziness and balance centre.
MAT: So where are these clinics?
SM: Yes, there is a full list on the British Association of Audio Vestibular Physicians website. But the main centres are GOSH, of course, UCLH in London, St George's in South London, and there are a few other centres in London, and then in the home counties as well. And then there are numerous other centres in the rest of the country, Alder Hay in Liverpool, Bolton, the Wirral, and in Cardiff in Wales and Glasgow in Scotland. There's a full list on the BARP website.
MAT: And are there any simple examination techniques that can be undertaken in a clinic or at the bedside by non specialists who suspect a child might have a vestibular problem?
SM: Yes, so examination starts as soon as you start calling the child in from the waiting area. You need to look at their gait, look for any dysmorphic features, what's the posture like, for example. Then you need to look at a focused examination of the cardiovascular, neurological and musculoskeletal systems. Then a detailed eye movement assessment is needed. So first you want to look at the ocular alignment, look for any squint that could be contributing to their problems. Then assess to see if there is a good, normal, full range of eye movements bilaterally.
Whilst doing this, you're also assessing for nystagmus. This is a really useful sign for us when assessing a child with dizziness or balance problems. It helps you to distinguish whether the cause of the problem is peripheral, so arising from the inner ear vestibular organs or the nerve, or central. As a general rule of thumb, peripheral nystagmus tends to beat in just one direction, whereas nystagmus that is vertical, so up or down, or changing direction, is more likely to be central. And then you also want to then look at saccades and smooth pursuit.
Next, we would suggest undertaking head impulse testing, which is also known as the head thrust test. This is a simple and reliable bedside test that can be used to detect a unilateral peripheral vestibular deficit. It works by testing the VOR, the vestibular ocular reflex, which I mentioned before. This reflex is helpful to maintain corrective eye position during any change in head position and to correct the eye movement rapidly so that vision remains on target, as I explained previously.
So to do this test, you need to sit in front of the child and ask them to fixate on a target. I usually ask them to look at the bridge of my glasses, or you can ask them to look at the bridge of your nose. But if they're too little for this, I would ask a colleague to stand behind with a small toy as a target. So they would stand behind me. I then move the head quickly and unpredictably to 10 to 15 degrees of neck rotation. It needs to be quite fast. A normal response would be for the eyes to remain on my target even after I've moved the head. In an abnormal response though, either to the right or the left, the eyes are dragged off the target by turning of the head and the child has to make a corrective saccade back to the target.
The presence of a corrective saccade indicates a deficient VOR on that side of the head turn, indicating a peripheral vestibular lesion on that side. This can be quite hard to detect initially, but I think if you were to practice undertaking this on all children with balance difficulties, falls, dizziness or vertigo in the clinic, you'll soon become familiar with doing this.
And then lastly, also assessment of dynamic and static balance.
You want to do Romberg's test where you ask the child to stand with their feet together and eyes closed. And this is positive if they step away from their original space due to unsteadiness or have very large motions of sway. Although this isn't specific just to a vestibular cause. It can be due to proprioceptive difficulties or a cerebellar disorder, for example.
And then tandem gait with heel to toe walking. This, I think, would be sufficient for a vestibular assessment that can be undertaken in a generalist settings, and you don't need any specific equipment to do this.
MAT: So we've covered quite a lot so far. We'll now start to move on to cover diagnosis and also aspects of treatment.
So when a child is referred to you at GOS, for example, what kind of process is there in terms of workup? Do you employ specialist tests and investigations?
SM: So I think we'll cover these last parts fairly quickly because I think from a general paediatric perspective most of what we should be covering and looking at and where I think the interest will lie for our listeners will be in history taking, examination and the common aetiologies which we've talked about.
But, out for interest, when these children come to a specialist clinic, such as the one at GOSH, the child is usually seen by one of the doctors first. We spend a long time going through the history and performing the examination. Of course, we make it fun, so testing of the eye movements is done with lovely big bags of toys, and we examine opportunistically. We're often running around after little ones, encouraging them to play while we observe their balance, rather than pushing them. towards formal examination, particularly if they're very young. And then they go on to have testing with the balance audiologist. Most of these tests are undertaken by assessing eye movements, usually with the child wearing goggles if they're able to, as we know that the eyes are the windows to the vestibular system. If they can't wear goggles, usually alternative means of testing can be found. So this isn't a concern for us. We usually say that a child of absolutely any age can have some form of testing if it's indicated, even tiny little babies. So age really shouldn't be a barrier.
Other things that we'd usually consider, depending on the presentation at the end of the assessment, are performing a lying and standing blood pressure with heart rate measurements, doing blood tests, including genetic testing, and testing for CMV as well.
And then performing scans, for example, MRI scan of the head or inner ear structures or CT scans.
Then, I think with children, we need to remember that MDT working is often crucial to establish the diagnosis and treating appropriately. So we might get together with local teams, particularly in neurology, occupational therapy, physiotherapy, the education settings, mental health, for example, to achieve the correct outcomes for the child going forward.
MAT: So just to draw things to a close now, say we have a child with diagnosed vestibular loss, what treatment options are out there for our patients?
SM: Yes, so treatment clearly does depend of course on the underlying cause. But as a general rule of thumb, treatment approaches can encompass simple lifestyle modifications to start with, often ensuring a child has the correct amount of sleep, food, hydration, and that they can minimize stress if it's there, can be hugely helpful, particularly in the context of migraine, as most of us know.
Medications might be used, but not often. We tend to avoid vestibular suppressant therapy, such as prochlorperazine, for example, as it might not be suitable for a child anyway, depending on their age, but it can also interfere with normal vestibular compensation processes. These drugs are also not a treatment. They're only for symptomatic relief, but they can have their uses in some select cases, maybe just as a temporary measure. And then exercises, so I've specifically not mentioned paediatric vestibular physiotherapy and that's because children tend to do very well overall in terms of compensation naturally in the vast majority of cases, given that most of them tend to move around a lot generally by themselves. So often we just encourage them to keep active, exercise, play sport where appropriate. And all of these things can be really great for strengthening the vestibular system overall. However, sometimes specialist paediatric vestibular physiotherapy input is needed and this can be accessed from specialist centres such as Great Ormond Street if needed.
If the source of the vestibular symptoms is psychological, then support from the school counsellor or CAMHS or other mental health therapy may be needed as well. So that's all we have time for today.
MAT: Thank you to Sarangi for joining me today and sharing this knowledge about a slightly lesser known specialty.
Thanks also to GOS Digital team and GOS Digital fellows, Emma Foreman and Sarah Ahmed, for facilitating this. We hope this session has been of interest to all who have listened.
SM: Thank you so much, Mara. It's been a pleasure to be here.
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