Simple Bedside Test Helps Diagnose Stroke

A novel electronic device that measures eye movements can successfully determine whether the cause of severe, continuous, disabling dizziness is a stroke or benign.

Researchers at Johns Hopkins Medicine (Baltimore, MD, USA) used the small, portable device to detect minute eye movements that are difficult for most physicians to notice in regular tests, such as the horizontal head impulse test, one of the best predictors of stroke. The test involves asking patients to look at a target on the wall and keep their eyes on the target as the doctor moves the patients’ heads from side to side. The test 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.


After performing the standard clinical test, the researchers repeated it using a video-oculography machine, goggles with a USB-connected webcam hooked up to a laptop and an accelerometer in the frame. Special software interprets eye position from continuous pictures of the eye, while the accelerometer measures the speed of the movement of the head. The researchers enrolled 12 patients in a proof-of-concept study; six were diagnosed with stroke and six with a benign condition. The patients then underwent confirmatory magnetic resonance imaging (MRI), which verified all 12 diagnoses. The study was published ahead of print on March 5, 2013, in Stroke.

“Using this device can directly predict who has had a stroke and who has not,” said lead author associate professor of neurology and otolaryngology David Newman-Toker, MD, PhD. “We’re spending hundreds of millions of dollars a year on expensive stroke work-ups that are unnecessary, and probably missing the chance to save tens of thousands of lives because we aren’t properly diagnosing their dizziness or vertigo as stroke symptoms.”

Strokes can be distinguished from benign peripheral causes of acute vestibular syndrome with three bedside oculomotor tests - the head impulse, nystagmus, and test-of skew. Using these tests is more sensitive and less costly than early MRI for stroke diagnosis in acute vestibular syndrome, but requires expertise not routinely available in emergency departments. Computerized tomography (CT) scans are therefore ordered for roughly 40% of patients who present with dizziness, but miss more than 80% of acute strokes occurring in the brainstem and cerebellum, making it impossible to rule out stroke in dizzy patients this way.

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