Goggles Differentiate Between Stroke and Vertigo
By Jessica Girdwain
A new electronic device called a video-oculography machine, used by a team of scientists at Johns Hopkins University School of Medicine, can measure eye movement to determine whether a patient’s dizziness results from a stroke or more benign vertigo.
David Newman-Toker, MD, PhD, an associate professor of neurology and otolaryngology at Johns Hopkins Medicine, explains that the gogglelike device measures eye movement in a way similar to that in which an electrocardiogram (EKG) measures heart physiology. “It’s not the same technology, but it’s the same ideology. Instead of measuring electric impulses the way an EKG works, the goggles use a video signal of the eye itself via a USB camera embedded in the frames to measure the acute physiology of the eye,” he says. An abnormal eye movement pattern can indicate whether a patient has suffered a stroke or has an inner ear problem.
The first study involving the new device enrolled 12 patients and recently was published in the journal Stroke. “Results are consistent and stable, and match what we see in our patients when we do exams [to determine whether someone has suffered a stroke]. We have more experience in this field than just published in the study,” lead study author Newman-Toker says. “We have confidence that as a result, the goggles, in the long run, will prove to be a significant new technology that influences diagnosis.”
Strokes that present with the well-known symptoms such as weakness on one side and difficulty speaking are detected fairly accurately, Newman-Toker notes. But not all patient presentation is easily identifiable.
Currently, when a patient presents in the emergency department (ED) with a possible stroke, a physician will make a judgment call about his or her level of concern that the patient is indeed having a stroke; the patient’s age and history of risk factors are major indicators of the possibility of a stroke.
If a stroke is suspected, the physician will order a CT scan. If a stroke is highly suspected, an MRI may be ordered. If either test is negative, the patient likely will be discharged and given antivertigo medication to treat his or her symptoms.
For accurate stroke diagnosis, the current testing may be inadequate or inappropriate. “We know from analysis that 40% of vertigo cases in the ED receive a CT scan, while only 1% or 2% get an MRI. CT scans are useless for detecting a stroke. These tests miss more than 80% of strokes that occur in the back part of the brain, the same area that controls balance and eye movement,” Newman-Toker says. Subsequently, many patients are falsely reassured that they have not experienced a stroke. “Some of these patients actually have a stroke, and some of them end up dying as a consequence,” he says.
Subtle eye movements, however, can indicate the only difference between a stroke in the back part of the brain and an inner ear disease. “That fact isn’t well-known, but it is something we’ve done a lot of work to establish over the past five years is accurate,” Newman-Toker says.
However, few physicians are trained to know the difference by analyzing eye movement, so Newman-Toker hopes the video-oculography machine could one day make it easier for other medical professionals to pinpoint a stroke via eye movement. “We’ve shown that eye movement is a better predictor of a stroke than an MRI with patients who have dizziness and vertigo symptoms,” he says.
The device ultimately may hasten the process of diagnosing a stroke in the ED. CT and MRI scans can take one to several hours to administer. If widely developed, the video-oculography machine could be placed on patients in a manner similar to an EKG machine. In practice, a physician would need to set up only a computer and the machine—a 10-minute procedure—with important results being immediately available.
Additionally, the new technology costs less than CT and MRI scanners—roughly $15,000 to $18,000 in the United States. And as the production volume increased, the price point likely would decrease. Newman-Toker hopes this would make the technology more affordable at the community level and therefore more accessible.
Currently the goggles are FDA approved for use only as a testing device and are not indicated for diagnosing stroke. However, Newman-Toker is seeking FDA approval for diagnostic use. “As we do more research, we will build the scientific foundation to prove that this device is better than the current practices in place. After that happens, I think the use of this device will become widespread,” he says.
However, Newman-Toker cautions health care providers who may be interested in buying the goggles for use in their practices that although the device’s future looks promising, it’s not yet ready for widespread use. “We don’t want to advise people to rush out and buy a pair tomorrow unless they are experienced in and trained for eye-movement analysis,” he says. “If this information—that eye movement can be used to diagnose stroke—is news to someone, they are frankly not ready for the device. We need to fully automate it to the point where it is independent of all expert knowledge.”
That may happen as early as five years from now. At that point, the information the device can deliver would be prepackaged so that any health care professional could use it. Newman-Toker says that is what he and his team are working toward. “We have a clear bridge from where we need to be for more accessibility,” he says.
The new device has the power to be transformative for both physicians and their patients. If the device can make the distinction between a patient with stroke and one with inner ear disease, such detection could save an entire group of patients from unnecessary hospital stays, along with the associated potential exposure to hospital infection, large medical bills, and radiation from imaging exams.
For now, Newman-Toker says health care practitioners who can adeptly distinguish eye movements associated with stroke from those related to inner ear disease and want to take their practice to the next level may want to consider this device.
— Jessica Girdwain is a Chicago-based freelance writer who has contributed health-related articles to several national magazines.