The research behind our work
From frustration to innovation
In 2015, endovascular treatment was shown to be significantly better than the established treatment with intravenous thrombolysis alone for acute ischemic stroke caused by occlusion of a large artery to the brain. Endovascular treatment had been developed since the early 90s and was now widely introduced into routine healthcare. However, the number of patients treated remained low. This mainly because the treatment only proved effective within the first 8 hours after onset and the vast majority of patients arrived too late.
It was the frustration of having an effective treatment, but not being able to give it to the majority of stroke patients that led us to design an alarm for stroke — a way to get help even when the patients are unable to call for it themselves.
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The intersection between technological and medical development
At the same time as effective stroke treatments were developed, portable devices based on three-axis accelerometers became widely available. Since unilateral arm paresis is one of the most common symptoms in stroke, in 83–90% of stroke patients at onset and is otherwise an uncommon neurological symptom, our hypothesis was that bilateral wearable accelerometers could act as a passive indication system for detecting stroke.
The art of separating stroke-affected arms from healthy
To distinguish arm paresis associated with stroke from everyday variations in arm movements, we turned to experts in signal processing and machine learning.
In a study comparing arm movements registered with bilateral accelerometer bracelets in a group of patients with recent stroke with persisting arm paresis was compared with healthy subjects’ arm movements. We showed that algorithms based on machine learning can identify stroke-affected arms with high accuracy based on 30–90 minutes of movement data, which is a short enough time for an alarm chain to react and bring the user to healthcare in time for effective stroke treatment.
How patients feel about Stroke Alarm
We have developed Stroke Alarm so that it can follow the user in everyday life with minimal interaction — day and night.
A user study showed that the majority of patients who used Stroke Alarm had a positive experience, and the vast majority would use a similar product again.
