Robert E. Harbaugh, MD
Courtesy of Penn State College of medicine


Published 1/1/2015
Peter Pollack

Unlocking the “Black Box” of Concussion

Concussion is a known problem, but long-term effects are difficult to track

The National Football League (NFL) has come under increasing scrutiny for its response to traumatic brain injuries (TBIs) sustained by players as the result of concussions. The long-term prognosis for players who have suffered repeated TBIs can vary, but the condition is associated with a range of outcomes that run the gamut from mild cognitive deficits to chronic traumatic encephalopathy (CTE).

To learn more about what the NFL is doing to address this issue, AAOS Now recently spoke with Robert E. Harbaugh, MD, FAANS, FACS, president of the American Association of Neurological Surgeons (AANS), director of the Penn State Institute of the Neurosciences, and a member of the NFL Concussion Committee.

AAOS Now: What exactly is a concussion?

Dr. Harbaugh: Although still used colloquially, the term “concussion” has actually fallen out of use a bit. The old definition of a concussion was a loss of consciousness associated with brain trauma. But brain trauma is really a spectrum from very minor disruption all the way through to fatal injury. Terms like “concussion” and “mild traumatic brain injury” make it difficult to give a very precise definition. Researchers are now looking at brain trauma in general, and that term can address a range of severities.

AAOS Now: How has the understanding of the gravity of TBI in sports changed over time?

Dr. Harbaugh: In the NFL, we’re trying to do everything we can to make the game safer, and we are taking any type of TBI much more seriously. We’ve standardized return to play criteria, added observers in the stadium box, and put independent neurological experts on the sidelines to help with the evaluation. So there has been a huge change in the way the NFL and society in general have approached the issue of TBI associated with sports.

Having said that, based on the overall data, it appears that the risk to players—at least prior to the collegiate and professional levels—is really very low. So this isn’t a health crisis in the way it has sometimes been portrayed. I suspect that in the past, the pendulum had swung too far to the side of “this isn’t anything to worry about.” But on the societal level right now, things may have swung too far in the other direction, to the point where it’s viewed as a real crisis. I don’t think that’s correct.

AAOS Now: CTE has received a lot of attention in the news media recently. Can you talk a little bit about that?

Dr. Harbaugh: CTE used to be called dementia pugilistica, or punch-drunk syndrome. It’s a clinical syndrome associated with repetitive blows and linked to motor dysfunction, Parkinson-like syndromes, and difficulty with cognition, memory, and judgment.

It was initially noted in boxers. A few years ago, a retired Pittsburgh Steeler who had all of the clinical indications of CTE died, and the findings on autopsy were identical to what had been described in boxers. Since then, several autopsies performed on former NFL players with behavioral abnormalities consistent with CTE have found similar results in their brains as well.

A group at Boston University has done the most work on this. Unfortunately, it’s very difficult to know what the incidence is. I believe we need to implement a registry-based approach to determine the incidence of CTE in players across all levels of sports. More importantly, we need to determine if any type of intervention can be used between the time a player finishes his career and the time CTE symptoms appear. Right now, that’s kind of a black box.

A player can have an NFL career, retire in his late 20s or early 30s, do well for 20 years, and in his 40s or 50s develop this syndrome. We really don’t understand the factors that may have occurred during that gap that could have contributed to the development of the disease. That’s the time during which it would be possible to intervene, and we need to delineate that better.

AAOS Now: Can you discuss the sideline diagnosis of TBI and when a player is ready to return to play?

Dr. Harbaugh: In the recent past, someone could get hit and actually lose consciousness, go back, pass a very brief sideline examination, and return to play the same day. That’s not going to happen anymore. The level of concern has increased considerably, and the recommendation is that any player who has any change in neurologic status related to trauma should not return to play that day. Present recommendations include cognitive and physical rest, followed by resumption of cognitive and aerobic activities, and eventual return to sports-related activities about a week after symptoms are no longer present.

It’s important to note that all of those recommendations are consensus-based and not derived from hard evidence, so it’s likely that they’ll change as we learn more. Right now, the preference is to err on the side of not returning a player to a game situation until there is absolute certainty that the player is asymptomatic.

AAOS Now: How do you balance the desire of coaches and players to remain in the game against the well-being of the player?

Dr. Harbaugh: If there’s any question, the physician needs to come down on the side of safety for the player. This is where I think the trainers are very handy. They get to know the players very well and can spot even subtle changes in behavior. The players will often deny symptoms, so it’s helpful to have someone who is familiar with the player. If there’s any question of whether a player has experienced a change in neurologic function because of trauma, that player should sit out of the game until a more thorough evaluation can be conducted.

AAOS Now: A lot of attention has focused on acute injury. Are there any warning signs that physicians should be aware of in the chronic sense?

Dr. Harbaugh: Most people who have a concussive injury will have a complete recovery within days—they don’t have headaches, they’re not dizzy, they can concentrate, their balance is good, their neurologic function has returned to baseline. But there is a group who—even after a single concussion—don’t have that expected recovery. Some of the more sensitive indicators are headache, spatial memory, reaction time, and balance. Those are the sorts of things that physicians really want to look at to make sure that none of those symptoms are present and that the player can pass some basic examination.

One of the things we’ve been working on at Penn State is a virtual reality system that enables objective testing of athletes for things like reaction time, spatial memory, and balance. Our goal is to make sure that players are really back to baseline before allowing them to return to a situation where they may be at risk.

AAOS Now: How important is it to take baseline measurements of these factors?

Dr. Harbaugh: It’s very important, and it’s also important to try to develop some type of testing that the players can’t manipulate. Players realize that the test may be used to determine whether or not they can return to play, so they may attempt some false answers or take more time than they really need to give themselves a little leeway after injury. Setting some type of baseline test that’s almost impossible to fudge is important, but that can be difficult and research is ongoing.

AAOS Now: Any final points you’d like to make?

Dr. Harbaugh: It is certainly important to take TBI very seriously and protect the patient. But I would like to make a case that—at least through the high school level—data suggest that it is safe to play football. At least one study has looked at high school football players from the decade of the mid 1940s to the mid 1950s and compared them to a cohort of students from the same era who did not play contact sports. Based on a review of medical records, the researchers found that playing football in high school was not associated with an increased risk of Parkinson’s, Alzheimer’s, dementia, or amyotrophic lateral sclerosis (ALS). And this was at a time when players did not have the protective headgear that they wear today or the more stringent rules against spearing or return-to-play after being hit.

I believe the pendulum may have swung a little too far. People are afraid to have their children participate in any contact sports, and I think that’s a mistake. We have a real crisis in this country in the form of childhood obesity, and every time we remove an option for physical activity, we make that worse. At least so far as the high school level is concerned, there’s currently no evidence that playing football puts a player at risk for long-term problems.

Peter Pollack is the electronic content specialist for AAOS Now. He can be reached at

Additional Information:
Savica R, Parisi JE, Wold LE, Josephs KA, Ahlskog JE:
High school football and risk of neurodegeneration: A community-based study. Mayo Clinic Proceedings, 2012;Apr;87(4) 335-340.