Dizziness, vertigo and nausea are common symptoms of an inner-ear infection. But they can also be signs of a stroke.
For doctors, especially those working in emergency rooms, quickly and accurately making the distinction is vital. But basic diagnostic tools, including the otoscope and simple eye-movement tests, are far from definitive. As a result, many doctors resort to a pricey imaging test such as a CT scan or an MRI. Nearly half of the 4 million people who visit U.S. emergency rooms each year with dizziness are given an MRI or CT scan, according to a study issued last month. Only about 3 percent of those 4 million people are actually having strokes.
For the 25 percent of strokes that restrict blood flow to the back portions of the brain, CT scans are a poor diagnostic tool, according to the study's leader, David Newman-Toker, an associate professor of neurology and otolaryngology at the Johns Hopkins University School of Medicine. "CT scans are so bad at detecting (these strokes) that they miss about 85 percent of them" in the first day after symptoms begin, he said. Even MRIs miss almost 20 percent of strokes if the test is done within the first 24 hours.
A new device offers a promising option for rooting out the cause of dizziness: eye-tracking goggles.
The goggles have a motion sensor for the head and a high-speed camera that records eye movements. They connect to a laptop that analyzes how the head and each eye -- the camera can record only one eye at a time -- move in relation to each other.
In March, Newman-Toker and his colleagues published the results of a small study demonstrating the goggles' effectiveness. The team used the device to check for stroke in 12 dizzy emergency room patients; it was accurate in all cases.