Stanford Medicine Newsletter Updates For the Local Community

 

Sudden impact

New center looks to define concussion

Paige Fisher was treated at the Stanford Concussion and Brain Performance Center, which applies objective criteria for diagnosing concussion.

   

Paige Fisher was pedaling along a narrow path on her way to a yoga class last January when she crashed head-on into another bicyclist. When she came to, she was bleeding profusely and surrounded by worried bystanders. Despite a visit to the student health clinic, a scan at the emergency room and appointments with her primary care physician, she continued to feel dizzy, sleepy and sensitive to light weeks after her wounds had healed. “I was told I had a concussion and to just rest,” said the 22-year-old Stanford graduate. But the lack of activity made her feel lethargic and depressed. “I was not getting better. I felt out of it and not like myself at all,” she said.

Fisher was referred to the Stanford Concussion and Brain Performance Center, where she underwent a series of tests to track her response rate and attention span. She was put on a regimen of treadmill training and vestibular rehabilitation therapy, an exercise program that retrains the brain to regain balance control and minimize dizziness.

“The center used metrics, measurements and data to track my progress, so it wasn’t just that I felt better — I could see the measurements of my improvement. I had been feeling like it was all in my head, so that was a real morale booster,” Fisher said.

A growing concern

The Stanford Concussion and Brain Performance Center was established last year to define objective criteria for diagnosis for concussion and to treat adults and children based on the physical response of the brain.

“Concussion remains the most underreported, underdiagnosed and underestimated head injury. It affects how we think, even though physical function may be intact,” said Jamshid Ghajar, MD, PhD, clinical professor of neurosurgery and director of the center at Stanford Medicine. He collaborates with Gerald Grant, MD, associate professor of neurosurgery. “It mainly affects the ability to focus — how a person interacts with the outside world. Poor attention is the most common cognitive impairment.”

Concussion injuries are gaining attention because of their prevalence among young athletes. Approximately 3.8 million people suffer concussions from sports and recreation-related activities in the United States each year — an estimated 100,000 of them among high school athletes. Almost half of all athletes do not report feeling any symptoms after a concussive blow, but people who have had a concussion are three times more likely to have a similar event and to experience slower neurological recovery.

Defining concussion

Currently, there is no universally accepted scientific definition of concussion, and both diagnosis and treatment vary from physician to physician. Symptoms can range widely and vary in intensity and duration. Doctors typically diagnose the condition by observing symptoms such as headache and dizziness and sometimes by testing reaction time, memory and comprehension. Brain scans, using magnetic resonance imaging or computed tomography, often show no physiological change.

Ghajar defines a concussion as a change in brain function after a direct or indirect force to the head, sometimes followed by a temporary loss of consciousness that results in neurological and cognitive dysfunction, such as disorientation, balance, slowed reaction time, blurred vision and impaired memory. The condition resolves by itself in a week in 92 percent of the cases, he said.

Response to impact

A concussion begins with an impact to the head, neck or torso, which causes a metabolic cascade within the frontal lobe of the brain, affecting the way it responds to stimuli. The result is a timing gap in the way the brain interprets and predicts what is taking place in the outside world. Ghajar likens it to the way a tennis player anticipates where and when to swing the racket to hit the ball at the right time and place. When the system is disrupted, the result is a delayed and variable reaction time.

“What I think is disrupted in concussion is prediction or anticipation,” he said. “The brain is not synchronized properly with the outside world, and its moment-to-moment prediction is impaired. It’s all about the timing.”

Ghajar has developed an eye-tracking device to evaluate how well a patient can anticipate the progression of a dot of light moving in a circle, a measure of how well one can synchronize with outside stimuli. Cameras track the eye’s ability to follow the dot’s movement, which tests predictive ability. A person with a concussion cannot track the light well, resulting in “jitters” in the eye movement in relation to the target. The system works, Ghajar said, because visual tracking and attention share similar neural areas in the brain.

He is involved in a large-scale study of military personnel, high school athletes and other groups to determine whether the degree of disruption in eye movements detected by the device correlates with concussion and recovery. Using this eye-tracking technology, he and his colleagues plan to establish measurable criteria for concussion and to determine when it’s safe for a patient to go back to normal activities. Ghajar is president of the Brain Trauma Foundation, an organization focused on developing best practice guidelines, conducting clinical research and educating medical professionals and consumers about concussion.

For Fisher, watching her progression on Ghajar’s eye-tracking system showed tangible proof that she was, indeed, recovering from her concussion. After almost four months of gradually building up her strength and focus, she finally was able to get back to all her usual activities, including bicycling — always with a helmet

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