The challenges & impacts of engineering for epilepsy

Hi, I’m Josh Reich, the CTO at Seer Medical, an Australian medical technology company specialising in the diagnosis and management of neurological disorders. I lead the teams building our software. In launching this blog, we’re hoping to highlight the work that our team is doing to use advanced technologies, from material science and electronics to software and interaction design to have a deeply meaningful positive impact on the lives of people with epilepsy. We have plans to dive into a range of topics and share our work with the broader technology community.

A very short introduction to the electrophysiology of epileptic seizures.

Epilepsy is a disorder in the brain that impacts about 1% of the world’s population, with about 1 in 26 people experiencing a seizure at some point in their lives, and about 50 million people currently diagnosed. For people who suffer epileptic seizures, their lives are punctuated by seemingly random events that can range from momentary loss of awareness, localised motor or speech disorders, through to the stereotyped tonic-clonic seizures, with loss of consciousness, muscle stiffness and violent shaking.

While there are a range of underlying causes, with roughly one third of folks having their first seizure in childhood, and others developing it later in life, epilepsy is characterised by spreading waves of electrical depolarisation in neurons. As different regions of the brain are impacted, their function is disrupted. This makes an electroencephalograph (EEG) a vital tool in diagnosing and localising the disease.

The function of neurons is complex. At the large cell body, dendrites reach out to nearby neurons where they meet at a synapse. Neurotransmitters, released into the synapse, bind with receptors on the dendrites and when the right combination and volume of binding occurs, it triggers an action potential down the long axon of the neuron. This action potential is a voltage that develops across the cell membrane, induced by the activity of ion channels that allow charged ions to cross the membrane. This voltage wave travels down the axon and then triggers the release of neurotransmitters at the synaptic terminals where further neurons are impacted.

In normal brain function, billions of neurons are processing information in a relatively uncoordinated fashion. This results in a near net-zero charge measurable on the scalp. During a seizure synchronisation between neurons occurs, and voltages in the order of 10’s of microvolts can be measured by an EEG.

To diagnose epilepsy, people with seizures are typically referred to a hospital setting where they are connected to an EEG and monitored by clinical staff around the clock for seven days. In Australia, patients can wait anywhere from six to 18 months for a diagnostic session. Waiting upwards of a year - while having seizures, while losing consciousness, while living with a suspected disease affecting their brain. Unnecessary, anxious waiting, just to find out what’s going on.

In 2017 our founders believed that there was a better way. A small group of neurologists, computational neuroscientists and electrical engineers got together to build Seer Medical with the aim of giving patients faster access to accurate diagnosis - from the comfort of their own homes.

Introducing Seer Medical

Seer has tackled the issues of accessibility and long wait times for hospital monitoring through two critical innovations. We’ve taken equipment that historically needed to be wheeled around hospitals on a cart and always plugged into the wall outlet and miniaturised it to a small wearable device. With low power analog to digital converters (ADCs), microcontrollers and radios, a patient can be fitted with electrodes in one of our offices, and can wear the device for 10 days without a recharge.

Redesigning the hardware from the ground up allowed us to take a patient-centric approach, so we’ve built our own magnetic EEG connector, that places the ADCs directly on the head, lowering noise, and allowing the patient to quickly remove it to shower — something they can’t do at all easily in hospital. We've also invented a new water-based electrode adhesive (WaterTabs®) to replace collodion, an inflammable noxious solution that is one of the leading causes of complaints with traditional EEGs. WaterTabs are innocuous and non-irritant, and can be simply washed off at the end of a study.

The other main innovation is our use of machine learning to interpret EEG signals. To the untrained eye (myself included), EEG traces look like squiggly lines. I’ve sat in frequently with neurologists as they review patient data. They have an uncanny ability to see through artefacts from patients chewing, head movement, and other sources of noise to find clear signs of the synchronised depolarisation that characterises epilepsy. For large seizures affecting the entire brain, these can be easy to identify. For smaller localised epileptiform events, the signs on the EEG are more subtle. Over the course of their training and careers, they can read the charts as easily as the rest of us can read writing, or musicians can read a score.

We’ve found that deep learning techniques from computer vision and audio processing — namely image segmentation, object detection, and audio event detection — can be readily translated into EEG applications. In recent years, these fields have experienced an explosion in cutting-edge research, yielding rapid improvement in automatic techniques for identifying complex patterns in data. In turn, this has yielded tremendous benefit for translatable applications, such as EEG analysis. When combined with large, well-curated, expert-verified EEG datasets, these techniques are able to identify regions of interest as well as a trained neurologist. At Seer, we’ve been successful in combining the best bits from these different fields to build state-of-the-art analysis techniques. And unlike many tech companies touting ML, we’ve demonstrated that our systems are clinically effective and are approved for use in many countries around the world.

This is a critical enabler for at-home epilepsy diagnosis. In a hospital setting, a clinician is constantly monitoring the patient. They’re watching the patient’s behaviour and observing the EEG traces. In addition to the cost of the bed, the 24/7 clinical presence is a significant driver of the cost of diagnosing the disease. Hospitals have more profitable uses of their facilities, so there is a limit to the number of patients who can be diagnosed. And with COVID-19, more patients are hesitant to spend extended periods in hospital settings. Our ML system means that instead of having to spend days watching a replay of the EEG, we can quickly direct our clinical staff to only review the relevant time windows, reducing the cost and time to diagnosis by at least one order of magnitude.

Our ML models are also starting to change the way that we can present EEG data. While neurologists who specialise in EEG reading are fluent with current visualisations, we believe that we can help them do their jobs faster and gain a deeper understanding of each patient with unique visualisations of the data that we surface. This is an interesting design challenge, and if we do it well, we’ll also be able to help patients and their primary carers get better insight into the nature of their disease.

Behind the scenes, we’ve deployed all of this in a compliant fashion on the AWS cloud infrastructure. Each patient study produces gigabytes of time series electrode data that is synchronised with many more gigabytes of high resolution video. The video allows clinicians to correlate what they’re seeing on the traces with patient behaviour. Given that we do over twice as many EEG studies as all hospitals in Australia, combined, our data set is now over 200TB. Our devops approach enables us to work quickly as we enhance our systems, unlocking the unique approach we take to analysing EEG data to enable more accurate diagnosis, faster, and cheaper.

Seizure prediction and challenging commonly accepted knowledge

If you look to the world's most commonly consulted source of information - Wikipedia - it will tell you that there are no effective ways of predicting seizures. The 2016 Epilepsy Foundation Community Survey Report reveals that the leading impact of the disease on patient’s lives is its unpredictability. And yet we have found that for individual patients the risk of seizures are predictable. We're proving that the common understanding of the disease is wrong. Not only does this allow us better schedule EEGs to capture seizures, but the positive impact on patients’ lives is difficult to overstate.

There’s a common misconception that for most patients seizures are triggered by well observed events (e.g., flashing lights). While this is true for a minority of folks, many live each day not knowing what the day brings. This can be an extreme burden. We’re currently trialing these forecasts via our mobile app with a range of patients, and the results are giving us hope that we can help people with uncontrolled seizures, and empower them to live their lives more freely.

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In my prior career, I was the CEO of an online banking company that was designed to help people live their financial lives with more confidence. We put our customers at the centre of our work and used design and technology to build a system for how people think rather than how banks work. Our work was rewarding and we built a community of fans who were able to develop a more healthy relationship with money to better achieve their financial goals.

As worthwhile as that work was, it pales in comparison to the impact we’re having here at Seer. Each day I’m humbled by the brilliance of the people across our teams and the stories we hear from our patients and those in the broader epilepsy community. I’m looking forward to sharing more of our stories and building upon our multidisciplinary approach by publishing our technical findings, challenges, and their connection to the deeply meaningful impact on patients’ lives. My hope is that by being more public with our work, we can also learn from you! If there are specific topics that you’d like us to dive into, or you just want to chat, please feel free to reach out to me.

This blog series may contain "work in progress" technological developments and it is meant to be a developer focused forum. As such, posts here are not intended to make any claims relating to clinical safety / efficacy of already cleared medical devices at Seer Medical. The discussion is general in nature and does not include any personally identifiable or health information.