Eye motion test shows promise for concussion detection
A precise way to diagnose concussions has been an elusive Holy Grail in medicine, despite a sharp increase in sports-related youth head injuries. But a Minneapolis neurosurgeon is reporting success with an experimental test that tracks eye movements of patients watching music videos.
Tested on 255 people, the eye tracking system correctly identified seven of the eight who had confirmed concussions, though it also registered false positives on a handful of healthy patients, according to results published Friday.
When healthy people watched music videos such as Shakira’s “Waka Waka” to Disney’s “The Lion King,” their eyes tended to stay tightly in sync. That synchronicity was lacking in people with concussions.
An 88 percent accuracy rate is superior to many commonly used screening tests, said Dr. Uzma Samadani, lead author of the research, who was recently recruited as a neurosurgeon and traumatic brain injury specialist from New York to Hennepin County Medical Center.
“We’re better than mammography for breast cancer,” said Samadani, whose study was published in the online journal Concussion.
Samadani’s results add to a growing body of research on ways to detect concussions — from blood screenings to balance tests to competing methods of vision tracking.
Heightened concern over head injuries, especially in youth sports, has fueled the search. ER visits for children with sports-related traumatic brain injuries rose 57 percent from 2001 to 2009, according to the U.S. Centers for Disease Control and Prevention.
Several states, including Minnesota, have responded with laws clarifying when athletes should be removed from play. But a lack of precise tests has made it hard for doctors, coaches and trainers to know for sure when collisions have caused brain injuries that require a player to be benched.
“The science hasn’t been able to keep up with the … explosion of awareness around the dangers of concussions,” said Dr. David Dodick, director of the Mayo Clinic’s concussion clinic in Arizona, “The diagnosis of concussion on any sideline is very subjective. It basically depends on the athlete reporting symptoms.”
Memory tests such as ImPACT have helped identify concussions in athletes, who generally aren’t cleared to return to sports until they perform as well as they did on initial baseline tests when they were healthy. But ImPACT is useless for athletes who didn’t take baseline tests, and requires a quiet computer room — so it can’t be easily provided at a sports venue.
Vision has long been an attractive alternative for concussion testing, because it is heavily intertwined with brain function, Dodick said. “The eyes are really an extension of the brain. They’re essentially hanging from the brain by two optic nerves.”
Mayo last year put its brand name on a vision test called King-Devick — a flip chart of sequential numbers that potentially concussed athletes must read as quickly as possible. If they’re slower by as little as a second than their baseline tests, the athletes likely have concussions that require removal from play, Dodick said.
King-Devick is already used on many sidelines, with the NFL, NHL and several state high school leagues adding it to their concussion protocols in the past year.
The need for objective tests was underscored by head injuries suffered in the NBA playoffs by star players this summer, Dodick said, as well as two female soccer players in the FIFA World Cup semifinals who returned to play shortly after they collided. “We know that 50 percent of athletes don’t even report their symptoms,” he said.
Despite the rapid spread of the King-Devick test, Samadani said there are key advantages to her eye-tracking system. (As founder of Oculogica, the company that manufacturers the system, she has a financial interest that she disclosed in her study.) It doesn’t require a baseline test, and patients don’t have to be literate. Its sophisticated eye-tracking technology means that it would likely have to take place in a clinic, but it can render a verdict after just 220 seconds of videos.
“Suppose you have a little kid and he gets hit in the head,” Samadani said. “You want to know, how injured is this kid and does he need to miss school? Does he need medication and should you be looking at therapies, or is this something that is relatively trivial and the kid can just go home and sleep it off? This will help you” make that determination.
Samadani said the study data will be presented to the U.S. Food and Drug Administration in the hope of getting federal approval for clinical care. The technological secret is in a system that is quick enough to track even minute eye movements.
More research will be needed, at the very least by another researcher who doesn’t have a direct financial interest, Samadani said. Addressing the false positive test results will be important as well. About two of every 10 healthy people in the study were screened in by the test as having potential concussions — an acceptable rate compared to other commonly used tests, but still a limitation.
FDA officials have raised a variety of additional questions, including whether the test was more effective with one kind of music video than another. But Samadani said it didn’t matter whether patients watched hip-hop or kiddie videos.
“It doesn’t seem to matter much what you are watching, or if you’re even watching the TV,” she said. “What matters is whether your eyes are moving together.”