by
Brendon Nafziger, DOTmed News Associate Editor | September 29, 2009
"We can do better at the bedside than technology can do in the same time window," Dr. Newman-Toker says.
The eye movement exam
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The eye exam is a simple, bedside procedure that takes only a few minutes and relies on three tests. The head impulse test, the most predictive of the three, involves rapidly spinning the patient's head to either side while they look at the doctor's nose. It tests for a reflex that keeps the eyes stable when the head is moving. In people with inner ear injuries, this reflex doesn't work properly. But when they have strokes in the back of the brain, this reflex is usually fine.
The other tests include alternately covering eyes while patients look at a fixed target to see if the eyes are misaligned vertically; and having the patients look to the right and left to look for jerky eye movements called nystagmus that changes direction. If either is present, it's usually a stroke.
Exam vs. exam
Dr. Newman-Toker is now trying to work out the cost-effectiveness of training a physician to take this approach versus developing a device to detect these eye movements in a more automated fashion, versus obtaining MRIs or other types of neuro-imaging to see what the optimal diagnostic strategy is for these patients. "We're now designing a research study that would get at the head-to-head comparative effectiveness of these different approaches."
Most front-line ER physicians, Dr. Newman-Toker says, are not trained to conduct the eye exams, and getting them up to snuff could be a massive undertaking. Still, it could help, especially in rural hospitals where there is little imaging equipment and often no neurologist on call. In fact, in many hospitals, Dr. Newman-Toker says, the standard diagnosis for strokes doesn't even use MRIs -- it uses CT scans, which can miss more than 80 percent of strokes in the first 24 to 48 hours.
According to Dr. Newman-Toker, there are about 2.6 million visits to the ER in the U.S. for dizziness each year, with about 150,000 of those being for AVS-like symptoms.
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