Dr Rachael Taylor wants to understand why we can suffer dizziness and balance problems after a mild head injury – when all the tests say there’s nothing wrong.

It’s what she calls a “massive jigsaw puzzle” and a project she hopes will lead to better assessments, and ultimately to better and more effective rehabilitation.

Rachael, who has a prestigious Aotearoa Fellowship from the University of Auckland’s Centre for Brain Research to study balance problems after mild traumatic brain injury (TBI) and also works one day a week at the New Zealand Dizziness and Balance Centre on Auckland’s North Shore, says it’s a puzzle she’s determined to help solve. The Eisdell Moore Centre is providing support to help Rachael solve this puzzle.

“[The whole area] is poorly understood,” she says. “That’s the reason why I chose to put in a research proposal on that topic.”

The issue, she says, is complex.

Scientists understand the five vestibular balance organs in the inner ear – the biological gyroscopes that tell us about our head position and our movement – but while they can test them following a brain injury, the tests usually don’t show there are problems.

“Even with all those tests, my experience at the New Zealand Dizziness and Balance Centre is that unless they’ve got a direct fracture going through their temporal bone, the inner ear function is still completely normal and the reflexes that we test are usually normal – within normal limits,” she says.

“There’s no consensus for how to rehabilitate these patients who report dizziness and balance problems. That’s because we don’t understand the mechanism.”

That means Rachael needs to look in other areas to find potential causes and answers.

To do this, she and her small team, which is funded by the Eisdell Moore Centre, are working with people with mild concussion – which accounts for more than 80 per cent of New Zealand traumatic brain injuries – and looking at a range of issues that could be causing dizziness and balance problems.

As well as the vestibular balance system, sometimes referred to as the “sixth sense”, vision and sensations from muscles and joints are also key elements.

A key target area is the cortex in the brain where information from the vestibular system and other sensory input is processed.

“They might be getting good input from their [senses] … but if they can’t process it properly and interpret it properly, then they’re going to be off balance,” she says.

Another target is the brain’s ability to “weight” the sensory information it’s getting so it can process it rather than being overwhelmed by it, and other inputs including spatial memory. Further targets include psychological factors such as anxiety and even a history migraine.

“Hopefully, if we understand the mechanisms, that can lead to the development of more effective rehabilitation programmes,” she says.

“There’s a few other things that I hope will potentially come out of it too.

“One thing is better characterisation of the types of dizziness or balance issues that these people experience. Identifying risk factors is another one for this type of problem – why do some people get these dizziness or balance problems and some people don’t? How do the problems develop?

“The other goal is to adapt the technology that we have to identify tests that will be useful in identifying balance problems in traumatic brain injury.

“I want to look more into how the brain is integrating information from the different senses and how the input from the ears – vestibular information – is being perceived by the brain.

“And if we can identify tests that are proving to be sensitive … then that could direct future test protocols.”

Rachael took up the prestigious Aotearoa Fellowship in 2018 with the aim of building a programme of research at the University of Auckland around vestibular function in humans.

She’s also looking to contribute to this section of the University’s Master of Audiology programme, and is developing other lines of work in balance research for the Eisdell Moore Centre.

Rachael followed her love of maths into a Bachelor of Computing and Mathematical Science at the University of Waikato but switched to a BSc majoring in psychology and neuroscience at the University of Otago, followed by a Post-Graduate Diploma in Science, then discovering a fascination with the body’s vestibular function.

That led her to a Master of Audiology at the University of Auckland and work as an audiologist, before she left for London in 2003 to eventually work with audio-vestibular physician Professor Linda Luxon at the National Hospital for Neurology and Neurosurgery.

She then did her PhD on Vestibular Evoked Myogenic Potentials in different vestibular disorders at Sydney’s Royal Prince Alfred Hospital under Associate Professor Miriam Welgampola and Professor Michael Halmagyi, and returned to New Zealand in 2016, where she worked as senior audiologist at Whangarei Hospital.

Her work at the University of Auckland puts her among the few scientists worldwide working on TBI-related dizziness and balance issues and the laboratory she’s establishing at the university will be one of just three centres in New Zealand that can test all five vestibular organs.

As to how many people she will be able to help with her work, it’s difficult to define.

“We see a lot,” she says.

“Not everyone who has had a brain injury has dizziness or balance issues, but exactly how common it is, because it’s so poorly defined, it’s very difficult to quantify.”