Balance Awareness Week (BAW) aims to raise awareness of vestibular disorders, and takes place annually in September.
As part of this year’s BAW (12th – 18th September), we spoke to Dr Barry Seemungal about his research into conditions relating to vestibular dysfunction, and the problems facing those who suffer from them.
Can you explain how the vestibular system works, and which aspects of it you are interested in researching?
Understanding how our balance system works is to understand how our species lifted itself off the ground, stood up and looked around. Human balance, involving two and not four feet, is a precarious act. It takes time to get it right – ask any toddler. Get it wrong and you fall; get it very right and you are a gymnast.
The vestibular organ in our inner ear is a marvel of engineering. It will rapidly detect the smallest of head movements and sends this information to the brain, leading to a cascade of responses, including reflexive responses in less than 10 milliseconds. An important reflex is the vestibular-ocular reflex that works by adjusting eye position to compensate for head movements. Because of this, when we move around we do not see the world as if through a very shaky video camera.
But the vestibular system doesn’t just stop with the reflex component. The signals ascend to more complex areas of the brain called the cerebral cortex, which are responsible for our thinking. The cerebral cortex receives signals from the vestibular organ, which indicates and detects movement, and we can then feel that we are moving. This aspect of perception is in contrast to the reflex component, which acts without you thinking.
My research is focused not simply on the reflex component, but on how that reflex function interacts with the vestibular perceptual system in the cerebral cortex. I’m interested in whether deficits in feeling that we are moving are important for our balance. The simple concept of your brain being aware of where you are in space, and whether that is important for maintaining your balance, is something that has not, bizarrely, been explored in any depth.
Why do you think that is?
Most investigators have assumed that the vestibular reflex system is capable of taking charge of all of our balance needs. However, although the reflex function might be important for a sudden lurch, the brain also needs to assess your orientation continuously. This would require some kind of ongoing process to update your position in space.
There have been studies in animals to show that a part of the brain called the cerebellum is particularly important for calculating spatial orientation, but it’s unclear as to whether the cerebellum is the whole story. We published a paper looking at the structural brain correlates of perceiving self-motion in space in healthy individuals, and we conducted the same test in a group of ballet dancers who are particularly adept at maintaining their orientation in space. We found differences in the two groups, primarily in the cerebellum, which supports the animal data. However, we also found important differences in the cerebral cortex in the two groups, which intuitively makes sense. With a function as important as balance, you wouldn’t simply leave it up to one part of the brain; you can imagine that lots of brain areas would want to have that information. It’s not unreasonable to expect that most of the brain areas that are responsible for these sensory and motor functions would want to have a signal that indicates self-motion as quickly as possible.
You were recently awarded an MRC grant. Can you explain in a bit more detail about what this study will be focusing on?
The MRC grant will look at how brain injury from trauma will affect vestibular functions, including balance, that are dependent upon cerebral cortical function. For example, we recently showed in acute stroke patients a region of the brain called the temporoparietal cortex is important for our spatial orientation when we are navigating in the dark using only our vestibular signals. This brain region acts as a sort of Sat-Nav. We have other tests of vestibular function that depend upon a healthy cerebral cortex and we think these tests might be sensitive markers of brain injury. Diagnosing and treating balance dysfunction in head trauma is important as these patients tend to be of working age and previous research has shown that vestibular dysfunction is an independent risk factor for being out of a job in the long term, following a head injury.
One of our hypotheses is that the visible balance disorder is a result of a disruption in the brain network, which mediates vestibular functioning. Since this brain network is quite diffuse, then this network might be fairly susceptible to injury. If you have a method for probing that network function, then it could be quite a precise test for head injury.
Vestibular conditions are typically considered uninteresting in neuroscience as there is the notion it is all to do with the inner ear. However, this notion is incorrect since the vestibular system is highly interconnected. For example, we showed that stimulating the inner ear directly resulted in changes in functioning of the visual cortex. Furthermore, brain diseases can directly affect vestibular functioning. For example, many patients with Alzheimer’s disease complain of both spatial disorientation and imbalance, both key functions influenced by the vestibular system. Despite this there is little known of higher vestibular functioning in dementia.
This lack of awareness of the impact and importance of vestibular function can make it initially difficult to convince grant-awarding bodies of the need for such funding, however, as ever it is up to the researcher to make the case by demonstrating both a clinical need and a sensible research question.
Untreated dizziness can destroy your life, and it often does.
– Dr Barry Seemungal
Given that vestibular conditions could be defined as “invisible” illnesses, do you think that patients often end up being stigmatised when trying to seek treatment?
I think this is very true. The vestibular symptom is often invisible, not only to lay people but to medical staff. If you have a tremor or broken leg, that’s very visible. A lack of recognition of an invisible, sensory problem is a big issue for many patients. Imagine if you felt a continuous sensation as if you were on a merry-go-round the whole day – it would be horrible. You wouldn’t be able to concentrate on anything. It might affect your job or your relationship and maybe get depressed. Untreated dizziness can destroy your life, and it often does.
Many patients with balance problems are diagnosed incorrectly with mental health issues. The patients stop going out because of the overwhelming sensory problems they experience in the outside world. Many patients are diagnosed as agoraphobic (a psychiatric condition that denotes a fear of open or public places), when in fact they have a balance problem. In this situation, we need to diagnose and treat the balance problem, as well as treating any mental health issues. Regrettably, many patients are just referred for their anxiety and agoraphobia, and they will not get better unless the underlying balance problem is also diagnosed and treated.
If patients are being routinely misdiagnosed, what is being done to challenge this?
I have produced some teaching videos for GPs for NHS England London. I am also involved in an NHS London common conditions working group trying to improve the treatment of all dizzy patients in the community. One idea is to develop a network linking the community with the acute hospital so that expertise can be exported through training, from the hospital to the community. I would like to facilitate the treatment of patients with simple balance disorders at source, in the community.
I’m very keen that the community deal with the simplest causes of imbalance quickly and correctly, as this has a number of positive knock-on benefits. Firstly, if you treat patients with a balance disorder quickly and correctly, then they do not develop chronic dizziness, including psychiatric symptoms. Secondly, it will be cheaper. If you treat patients quickly, then it removes the need for them to go to hospital and see a consultant in an expensive clinic. You can also prevent the development of chronic dizziness, which is even more costly because the patients repeatedly attend their GP practice. If the patient is young, it means that they can’t work, and the socioeconomic consequence to society as a whole is quite important. All of these things – if they can be done in the community – can have a major health and hence, socioeconomic impact.
The other thing I want to touch on is the elderly. Falling is a major component of mobility and mortality in the elderly, and there is one condition that can be diagnosed very easily and cured in the community called Benign Paroxysmal Positional Vertigo (BPPV). In the current NICE guidelines, there is no mention of diagnosing and treating BPPV. I am trying to change that, having written a letter to the British Medical Journal on this issue. I have also been in touch with the NICE Centre for Guidelines and they will revisit this issue for their next revision. The treatment for BPPV is a very simple manoeuvre, it costs nothing, and if we enable local medical practitioners to carry it out then the impact will be huge.
Ultimately the clinical management of balance disorders comes back to the diagnosis: if you can make the correct diagnosis, then usually there is a treatment available. The good thing about treatment for balance disorders is that they work, and we have in some situations curative treatments for some very simple disorders, such as BPPV. The research domain is still important because there are some areas that we don’t understand in terms of mechanisms. It might then lead us to develop new treatments, but we first have to understand the disease process.
I would like patients to know that balance and dizziness problems are amenable to clear cut diagnosis and specific treatment which is usually successful
– Dr Barry Seemungal
Do you think that awareness-raising events like BAW can help make people more conscious of the issues that we have been discussing?
Yes, I hope so. I would like patients to know that balance and dizziness problems are amenable to clear cut diagnosis and specific treatment which is usually successful. Although there is much to understand through research, the knowledge that we already have is not being implemented.
Do you have any advice for patients who are currently seeking treatment?
When you go for an assessment by a doctor, you need to come away with a discrete diagnosis and an appropriate treatment plan or with a plan to refer you to someone who can provide such a plan.
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