Concussion: Mayo's multidisciplinary approach
Few neurological conditions have sparked as much public discussion as concussion. Injuries sustained by professional athletes and U.S. soldiers in combat zones have focused attention on the long-term effects of repetitive concussive injury. Once dismissed as "just having your bell rung," concussion is the focus of a multidisciplinary group of physicians at Mayo Clinic who provide enhanced treatment for patients as well as research the role of concussion in age-related neurodegenerative disease.
"Our practice has always considered concussion for what it is — a traumatic brain injury along the spectrum of injury severity and mechanism," says Allen W. Brown, M.D., a physiatrist at Mayo Clinic in Rochester, Minn., who specializes in rehabilitation after acquired brain disorders.
The integrated approach, which is pursued at all three Mayo campuses, is especially appropriate for concussive traumatic brain injury because symptoms vary widely among individuals and span the fields of neurology, physiatry, psychiatry and psychology. "Concussion must be approached from every angle," says Bradley F. Boeve, M.D., a neurologist at Mayo Clinic in Minnesota. "Just treating headache or memory problems does not treat the whole patient. That is the value of a multidisciplinary program."
Recognizing what patients need
The vast majority of traumatic brain injuries — an estimated 70 to 90 percent — are mild or concussive. Although Mayo physicians treat soldiers and professional athletes, most of the practice consists of patients who suffer concussion from routine work- and sports-related injuries. Concussion doesn't always involve loss of consciousness or post-traumatic amnesia, and neurological imaging is typically normal. Thus, concussion is a clinical diagnosis, with headache the most common symptom. Other symptoms include dizziness, nausea, vomiting, balance problems, mood changes, and difficulty with concentration and memory.
For most patients these symptoms ease with rest, limited activity and symptom management. But patients whose symptoms persist for weeks or months can benefit from rehabilitative intervention. At Mayo, a comprehensive evaluation — which may include behavioral neurological testing, orthopedic consultation for physical injuries and psychological assessment — is often pre-scheduled based on the individual patient's needs. Afterward, a document is prepared that summarizes the team's recommendations for follow-up care at Mayo or in the patient's community.
Psychological evaluation is a key component of Mayo's treatment model. "Just as important as the intricacies of the brain injury is whom the injury happened to," notes Thomas Bergquist, Ph.D., L.P., a clinical neuropsychologist at Mayo Clinic in Minnesota. A variety of psychological and environmental factors are known to influence recovery after brain injury. As just one example, Dr. Bergquist says, "Patients' personality styles can drive their symptomatic complaints. A patient with concussion who perceives his or her circumstances as more stressful is going to present in a different manner from someone who isn't wired that way." For patients with persistent symptoms who are experiencing their situations as highly stressful, cognitive behavioral therapy can decrease negative thinking and significantly improve quality of life.
Unraveling controversies associated with concussion
For physicians, one of the biggest challenges is advising patients about the long-term effects of concussion and about when it's safe to return to play or to work. Second impact syndrome, a complication that arises when a patient recovering from an initial concussion sustains a subsequent concussive injury, "dramatically increases the chances of some permanence to the brain injury," Dr. Boeve says.
Repetitive injuries have been implicated as contributing to the neurobehavioral symptoms of retired professional athletes who are diagnosed postmortem with chronic traumatic encephalopathy (CTE), a condition characterized by degeneration of brain tissue and accumulation of tau and other proteins. But Dr. Boeve notes that many former athletes show no symptoms of CTE or any other neurological disorder.
In an article published in the April 2012 edition of Mayo Clinic Proceedings, Mayo neurologists compared the medical records of male students in Rochester, Minn., who played high school football between 1945 and 1956 with non-football-playing male students from the same schools and time period. The study found no increased risk of developing dementia, Parkinson's disease or amyotrophic lateral sclerosis for the former football players.
"Yet this was in the era of leather helmets with no face masks, less regard for concussion, and no rules against spearing or head-first tackling," Dr. Boeve says. "There's little doubt that repeated injuries to the head aren't good for you. But when are they clearly bad for you? In other words, why is it that some people have neuropsychiatric problems years later after head injuries while others do not? These are important scientific and societal questions for which we do not have answers yet." Possible factors may include:
- The nature of the injury
- The cumulative number and severity of the injuries
- A person's genetic predisposition
- Other medical cofactors
- Injuries that occur outside of sports or a job
"Because abnormal tau protein deposition is a key feature of CTE, it makes sense that the tau haplotype or some other variants in the tau gene, or other genetic or environmental factors that affect the dynamics of tau deposition and clearance in the brain, have some play," Dr. Boeve says. "But TDP-43 deposition is also relatively common in CTE, and this protein is likely involved in inflammation or response to neuronal injury, or both. Also, there may be some other proteins that we don't even know about yet."
Documenting the incidence of traumatic brain injury
Few objective estimates of the incidence of traumatic brain injury include all ages and injury mechanisms, both sexes and the full spectrum of events, from very mild to fatal. But in a study published in the November 2011 issue of Epidemiology, Dr. Brown and colleagues documented an incidence rate of 558 traumatic brain injuries per 100,000 person-years in Olmsted County, Minn., from 1987 to 2000.
Among the 1,257 medical records reviewed, 56 percent of cases were male and 53 percent of cases were symptomatic. Mayo researchers also developed the Mayo Classification System for Traumatic Brain Injury Severity, which captures a larger number of cases than single-indicator systems.
In this research, as well as in clinical care, Mayo's integrated approach is essential. "Every individual who experiences a concussive traumatic brain injury has a unique genetic background, set of psychosocial circumstances and clinical problems. Consideration of these characteristics is the key driver of efficient medical evaluation and effective management," Dr. Brown says. "At Mayo Clinic we customize the approach to remain focused on the needs of our patients and their families."
For more information
Savica R, et al. High school football and risk of neurodegeneration: A community-based study. Mayo Clinic Proceedings. 2012;87:335.
Leibson CL, et al. Incidence of traumatic brain injury across the full disease spectrum: A population-based medical record review study. Epidemiology. 2011;22:836.
Malec JF, et al. The Mayo Classification System for Traumatic Brain Injury Severity. Journal of Neurotrauma. 2007;24:1417.