Concussion: Determining when the brain has recovered
A sudden stop, a blow to the body, or a sharp twist of the head may make an athlete feel momentarily dazed, dizzy or nauseated. Typically, the athlete would play through these symptoms or return to play as soon as he or she felt better. Yet, days and months later, that same athlete could be plagued by headaches, difficulty concentrating and mood swings.
Mental exertion or a return too early to physical activity before a brain injury is resolved can worsen symptoms and puts athletes at increased risk of repeat injury with potentially permanent neurologic consequences. Until fully recovered, the brain is in crisis. Injured again, the crisis could turn life-threatening.
Second-impact syndrome, a rare but usually fatal syndrome predominantly affecting young male athletes under the age of 18 years, is a devastating consequence of returning athletes to play before complete recovery.
Determining when the brain has fully recovered is critical to the long-term health and even survival of someone who has sustained an initial concussion. The Department of Neurology at Mayo Clinic in Arizona is addressing this and other issues surrounding concussion by offering complimentary baseline and after-injury computerized cognitive testing to all athletes of high school and middle school age in the state.
In addition, the department has founded a new comprehensive concussion program and is working to develop a sports neurology subspecialty for neurologists nationwide.
Complimentary baseline cognitive testing
In the face of heightened public concern about concussion, several states have mandated through legislation that athletes recognized as experiencing a concussion be immediately removed from play and not allowed to return to play until evaluated and cleared by a licensed health care provider.
However, without an objective measure, such diagnostic decisions are difficult even for those providers with expertise in dealing with brain injury. Results of the neurologic examination may be normal. Standard imaging, such as CT and MRI of the brain, lacks the resolution to show microscopic structural and metabolic changes in the recovering brain. And the subjective assessment of athletes, many of whom do not recognize the connection between their symptoms and a concussion or fail to report their symptoms in the interest of returning to their sport, can be unreliable.
Cognitive testing is often the only viable and objective measure of impairment and recovery, but to be effective, it must be measured against an individual's pre-injury baseline. Administered online, the cognitive baseline and after-injury test takes about 10 minutes to complete. It assesses skills such as memory, attention, learning, reaction time and processing speed. Students can share the results with coaches, athletic trainers, and the health care provider of their choosing.
In its first month of distribution, more than 25,000 athletes completed the testing. "While advances in helmets and protective equipment are important, there is a limit in their capacity to prevent concussion, and we may be nearing that limit," says David W. Dodick, M.D., a neurologist at Mayo Clinic in Arizona, director of the comprehensive concussion program, and president of the American Headache Society.
"Educating athletes, coaches, parents and athletic trainers about the symptoms, signs and potential long-term effects of concussion and repeated concussion is critically important," says Dr. Dodick. "Preventing concussion is as important as detecting it. Emphasizing the importance of mutual respect among players, eliminating head hits and fighting, and teaching young athletes who are involved in collision sports how to deliver and absorb a body check or tackle will go a long way to minimizing the frequency of concussion."
He also notes that it is important to be aware that children are particularly vulnerable to concussion. The developmental and maturational changes that occur in the brains of children appear to render them vulnerable to concussion, with symptoms that may take longer to resolve. In addition, concussions are more frequent in female athletes than male athletes, possibly because of their smaller neck girth, which does not provide the stability required to prevent the angular or rotational acceleration of the head that is a common mechanism of concussion.
As Dr. Dodick puts it, "Injured brains need rest — both cognitive and physical." He notes that recovery typically takes more time in a child than an adult. He goes on to say, "Not only is the developing brain more susceptible to injury, but an injury of similar magnitude will have a greater impact on a 12-year-old child than a 28-year-old adult. Repeated concussive injury can affect cognitive development, with consequences for learning and future employment. The concussed brain is a brain in crisis, and even a return to cognitive activities at school can stress the brain, amplify symptoms and prolong recovery."
Comprehensive concussion program
As part of its commitment to patients with concussion, Mayo Clinic in Arizona has established the comprehensive concussion program, led by Dr. Dodick. Reflecting the three shields of Mayo Clinic, it focuses on patient care, education and research.
The care of patients treated through the program will be managed by an interdisciplinary team that includes 13 subspecialties.
This past August, in conjunction with Arizona State University and Phoenix Children's Hospital, Mayo Clinic in Arizona held a concussion education and awareness summit designed to educate the general public, athletes, athletic trainers and directors, coaches, and health care providers about concussion. The day the concussion summit was held was proclaimed "Arizona Concussion Awareness Day" by the governor of Arizona.
The comprehensive concussion program will also conduct research. Working with clinical researchers at Mayo Clinic in Rochester, Minn., Dr. Dodick and colleagues are beginning a prospective study in Junior A League hockey players to evaluate the correlation between clinical, imaging, and serum biomarkers and in-helmet g-force measurements and outcomes following concussion.
Dr. Dodick is also working with his colleagues in Arizona on developing research protocols to:
- Evaluate the cellular pathophysiology of concussion
- Identify clinical, imaging or neurophysiological biomarkers that are diagnostic for concussion
- Identify risk factors and prediction models for persons at risk of long-term neurologic sequelae such as dementia, stroke or psychiatric disease
In the future, for example, there may be an imaging signature on proton MR spectroscopy that indicates when an individual's brain has actually recovered from concussion, rather than relying on subjective reporting of symptoms or on subtle or absent findings on the physical examination.
Dr. Dodick points out that evidence in the experimental and imaging literature shows that it takes much longer for the brain to recover from concussion than outward symptoms might suggest. "Right now, we're dependent on measures that require us to infer recovery. I want to know not only when athletes tell me they're back to baseline, but when their brain has returned to its metabolic baseline. It's all about when the athlete's brain is safe to return to play."
Sports neurology subspecialty
Dr. Dodick and his colleagues are collaborating with four other institutions to become among the first programs to offer accredited fellowships in sports neurology. Currently, most sports medicine programs are part of a physical medicine and rehabilitation or orthopedic practice and focus on the physical aspects of recovery.
A sports neurology program would bring neurologic expertise to the practice of managing athletic injuries related to concussive brain injury, among other neurologic aspects of athletic participation, such as peripheral nerve injury and neuromuscular and movement disorders.
Points to remember
- Most sports-related concussions are never diagnosed because athletes may not recognize or report the symptoms of concussion.
- Among people who are 15 to 24 years old, sports are second only to motor vehicle crashes as the leading cause of traumatic brain injury.
- Annually, 3.8 million children and adults in the United States experience a sports-related concussion.