Dr Millie Nakatsuka | Decoding Dizziness in the Emergency Room

Jul 27, 2023 | Health and Medicine

Acute vestibular syndrome is one of the most common reasons people present at hospital with dizziness. The symptoms can arise from damage within the brain or the ear, and specialist medical knowledge or equipment is typically needed to determine the specific cause. Dr Nakatsuka from the University of Sydney in Australia has conducted a large-scale analysis and review of the published literature to determine if well-trained emergency physicians can differentiate between the two causes using a quick bedside physical examination without expensive special equipment.

Acute Vestibular Syndrome

Acute vestibular syndrome (AVS for short) is the onset of sudden and intense feelings of spinning or dizziness, often accompanied by nausea, balance problems, and involuntary eye movements known as nystagmus. These symptoms can all be caused by damage or disease in the vestibular system – the network responsible for maintaining our sense of balance and spatial awareness. AVS can either be central (i.e., related to the brain) or peripheral (i.e., related to the inner ear). Knowing the location of the damage helps doctors identify which patients may be suffering from a potentially life or brain-threatening medical condition. This is because central AVS is associated with severe morbidity. In contrast, peripheral AVS is a common condition of the inner ear or 8th cranial nerve, which is not lethal (e.g., mild viral infection).

Central and Peripheral Causes

Diagnosing AVS and categorising the cause as either central or peripheral can be achieved by gathering a medical history, conducting physical and neurological examinations, and using complex diagnostic technology such as video-oculography (VOG).

Doctors and healthcare workers can perform a HINTS examination to differentiate between central and peripheral AVS. The HINTS examination consists of three components: Head Impulse, Nystagmus, and Test of Skew. The head impulse test involves rapid horizontal movements of the patient’s head while the patient focuses on a fixed point. Nystagmus are involuntary eye movements. Factors such as the presence or absence and direction of these movements can indicate if AVS is central or peripheral. The test of skew analyses the alignment of the eyes; in central AVS, imbalances in the eye muscles can lead to one eye appearing higher than the other. The original HINTS examination was established in 2009. Since then, variations have been released, including the HINTS-PLUS, which includes a hearing test, and the STANDING algorithm (SponTAnous or positional, Nystagus Direction, Head Impulse test, StaNdinG).

VOG uses video goggles or a specialised camera to track a patient’s eye movements. It is highly accurate and may capture subtle abnormalities that would be missed by a physical examination. It is also a highly specialised piece of equipment requiring trained healthcare staff to perform the tests and interpret the results.

Problems with Differentiation

A recent review paper found that less than 20% of patients who came to hospital with severe dizziness underwent a HINTS examination. Several studies have suggested that only specialised doctors such as neuro-ophthalmologists or neuro-otologists (specialists in eye or ear problems relating to the nervous system) are able to correctly conduct and interpret physical and neurological examinations such as the HINTS examination (which is better than an early MRI in identifying stroke). The findings of these studies are particularly concerning when we think about the care of patients attending rural or remote hospitals that may not have access to doctors in every speciality or VOG technology.

Dr Millie Nakatsuka of the University of Sydney in Australia has a special interest in neuro-ophthalmology and a particular interest in health inequality in regional and rural hospitals. Working with a multidisciplinary team, Dr Nakatsuka conducted a large-scale review of published studies to evaluate whether appropriate training and education can allow emergency doctors to use the HINTS examination (or the latter variant) and, thus, effectively distinguish between central and peripheral AVS.

The team began by looking at 1,757 results from all the major clinical journals and clinical trial records. Of these, 27 were deemed appropriate for further consideration. Articles were screened against multiple factors to ensure they met the stated criteria for clinician education and did not contain significant bias. After being screened, five studies were available for qualitative (descriptive and interpretative) analysis and two for quantitative (numerical) analysis.

More information was available on the STANDING algorithm than the traditional HINTS examination and its variations. Data supported the proposal that emergency doctors who are well-trained and educated can use the STANDING algorithm to identify central AVS in comparison to AVS with a peripheral cause. The STANDING algorithm offers high levels of sensitivity – meaning that 96% of cases of central AVS were accurately detected, and also high levels of specificity – meaning that 88% of non-central AVS cases were ruled out, when administered by trained emergency doctors. 

The researchers did not find enough evidence to fully support emergency doctors’ use of the original HINTS examination. However, they did report that two separate research studies are currently being conducted to assess the reliability of HINTS when performed by trained emergency doctors.

Implications for Diagnosis in Resource-limited Settings

Dr Nakatsuka’s study is the first provision of high-quality evidence supporting the diagnostic accuracy of the STANDING algorithm when conducted by trained point-of-care emergency doctors. As such, the team’s findings contradict previous reports concluding that bedside physical examinations for AVS should only be conducted by specialist doctors.

In Australia, only 25% of public hospitals are in major cities, with rural and regional hospitals facing large disparities in access to medical specialities and diagnostic technology such as VOG. The results of Dr Nakatsuka’s work are particularly important for less well-equipped hospitals as they highlight that if staff are given adequate education and training, patients will be able to be rapidly and accurately classified as having central or peripheral AVS without having to travel to a large well-resourced city hospital (which is not practical or feasible).

Increasing interest in using smartphones to record eye movements to aid AVS diagnosis also emerged in Dr Nakatsuka’s work, illustrating the useful application of technology and clinical skills. She hopes to build upon this current work by conducting further research on the education and training needed by point-of-care healthcare professionals to provide robust AVS differential diagnoses.






Dr Millie Nakatsuka
Discipline of Clinical Ophthalmology and Eye Health
University of Sydney

Dr Millie Nakatsuka gained her medical degree from Bond University in 2013 and has since specialised by obtaining a Master of Medicine (Ophthalmic Science) from the University of Sydney. Over her career to date, Dr Nakatsuka has gained valuable experience in various health services across Australia, working in emergency medicine, general medicine, ophthalmology, and psychiatry. She is particularly interested in neuro-ophthalmic emergencies, eye movement and cognitive function abnormalities in schizophrenia, and the potential ocular complications of medications. Dr Nakatsuka is currently studying towards a Master of Public Health with a focus on evidence-based and cost-effective clinical practice. Her overarching aim is to address health inequality in regional and rural hospitals in Australia.


E: [email protected]


Emma E. Molloy, West Moreton Health Service, Queensland, Australia


M Nakatsuka, EE Molloy, The HINTS examination and STANDING algorithm in acute vestibular syndrome: A systematic review and meta-analysis involving frontline point-of-care emergency physicians, PLoS ONE, 2022, 17(5), e0266252. DOI: https://doi.org/10.1371/journal.pone.0266252


We encourage all formats of sharing and republishing of our articles. Whether you want to host on your website, publication or blog, we welcome this. Find out more

Creative Commons Licence (CC BY 4.0)

This work is licensed under a Creative Commons Attribution 4.0 International License. Creative Commons License

What does this mean?

Share: You can copy and redistribute the material in any medium or format

Adapt: You can change, and build upon the material for any purpose, even commercially.

Credit: You must give appropriate credit, provide a link to the license, and indicate if changes were made.




Professor Kim McDonough – Professor Pavel Trofimovich | New Insights into Non-verbal Aspects of Second Language Learning

Professor Kim McDonough – Professor Pavel Trofimovich | New Insights into Non-verbal Aspects of Second Language Learning

Although most people study a second language in school, this education alone is seldom sufficient to achieve the level of proficiency needed to live in a foreign country. But in a world where global migration is increasingly common, learning a second language has become essential for millions of people. Professors Kim McDonough and Pavel Trofimovich at Concordia University, Canada, study language learning, and in doing so, are helping those trying to become competent in the use of a second language.

Dr Jon Neill | The Impact of Trade Deficits in America

Dr Jon Neill | The Impact of Trade Deficits in America

Former President Donald Trump promised to bring jobs back to the U.S., arguing that the trade deficit was responsible for slow economic growth and costing the economy jobs. While the Trump administration popularised the issue, historically, the broad impact of trade deficits has been contentious. Dr Jon Neill is a Professor of Economics at Western Michigan University. His computational modelling has shown that U.S. residents would experience a slight loss if consumer goods currently being imported from countries like China, were produced domestically instead. His calculations question whether the net benefit from trade with low-wage countries is warranted, given the distributional impact of that trade.

Dr Kyla Zatti | Aquaculture Feed: Progressing the Use of Algal Oils in Salmon

Dr Kyla Zatti | Aquaculture Feed: Progressing the Use of Algal Oils in Salmon

Salmon and other seafood represent a large and important food source. Traditionally, salmon diets consisted mainly of fish, although over the last decade, they have become more vegetable based. However, salmon require essential lipids, which are hard to find except in fish oil. Dr Kyla Zatti and a group of scientists at BioMar have been working to effectively bypass fish oil in their aquafeed by going to the original source of the lipids while maintaining the welfare, growth, and quality of the fish produced.

Professor David E. Sugden | James Croll, Ice Ages and Ice Sheets

Professor David E. Sugden | James Croll, Ice Ages and Ice Sheets

The phrase ‘standing on the shoulders of giants’ is often attributed to Sir Isaac Newton, meaning that scientific progress is only possible due to the contributions of the scientists who came before. However, many of these giants’ contributions are often forgotten or ignored in favour of their more famous peers. In the field of glaciology, Professor David E. Sugden from the University of Edinburgh is aiming to draw attention to one of the overlooked giants of his field – James Croll, whose work on Ice Age Theory is still relevant today.