Scientists have used a portable electronic device that measures eye movements to successfully determine whether the cause of severe,continuous and disabling dizziness is a stroke or something benign.
“Using this device can directly predict who has had a stroke and who has not,” said lead researcher David Newman-Toker from Johns Hopkins Medicine. Newman-Toker said if additional larger studies confirm these results,the device could one day be the equivalent of an electrocardiogram (EKG),a simple noninvasive test routinely used to rule out heart attack in patients with chest pain.
Universal use of the device could “virtually eliminate deaths from misdiagnosis and save a lot of time and money”,he added.
To distinguish stroke from a more benign condition,such as vertigo linked to an inner ear disturbance,specialists typically use three eye movement tests that are essentially a stress test for the balance system. In the hands of specialists,these bedside clinical tests (without the device) have been shown in several large research studies to be extremely accurate – “nearly perfect,and even better than immediate MRI,” said Newman-Toker. One of those tests,known as the horizontal head impulse test,is the best predictor of stroke. To perform it,doctors or technicians ask patients to look at a target on the wall and keep their eyes on the target as doctors move the patients’ heads from side to side.
But it requires expertise to determine whether a patient is making the fast corrective eye adjustments that would indicate a benign form of dizziness as opposed to a stroke,said Newman-Toker.
For the new study,researchers instead performed the same test using a small,portable device – a video-oculography machine that detects minute eye movements that are difficult for most physicians to notice.
The machine includes a set of goggles,akin to swimming goggles,with a USB-connected webcam and an accelerometer in the frame. The webcam is hooked up to a laptop where a continuous picture of the eye is taken. Software interprets eye position based on movements and views of the pupil,while the accelerometer measures the speed of the movement of the head.
The technology,Newman-Toker said,could someday be used in a smartphone application to enable wider access to a quick and accurate diagnosis of strokes whose main symptom is dizziness,as opposed to one-sided weakness or garbled speech.
The device developed by Denmark-based GN Otometrics is not yet approved for use in US. The study results were published in the journal Stroke.