Concussion in Sports

Recently, several journals have published articles on various aspects of head injury in sports. The Journal of the American Medical Association (JAMA) and the American Journal of Sports Medicine have published articles of particular interest. The articles in JAMA focus on high school and collegiate athletes and raise concerns regarding the long-term consequences of repeated concussion. The American Journal of Sports Medicine article is a wonderful review of what is known about the physiological reactions to head trauma, some potential long-term consequences, and evaluation and management of the head-injured athlete.

This large observational cohort study compiled data from 246 athletic trainers involved in a variety of high school varsity level sports including boys' football, wrestling, baseball and field hockey; girls' volleyball and softball; boys' and girls' basketball; and boys' and girls' soccer in 235 U.S. high schools during one or more years from 1995-1997. The intention was to determine how many mild traumatic brain injuries (MTBI) occurred and the frequency of occurrences for each of the sports included.

The researchers define MTBI as an injury for which the player was removed from participation and evaluated for a traumatic brain or head injury by the athletic trainer, physician or both prior to returning to participation. There were 23,566 reported injuries in the 10 sports over the three-year study period. Football accounted for 63.4% of injuries; wrestling, 10.5%; girl's soccer, 6.2%; and boys' soccer, 5.7%. Boys' and girls' basketball each accounted for about 5% of injuries. Injuries from softball, baseball, field hockey and volleyball accounted for 1% or less each. The average time lost from participation was three days. Football injuries accounted for all six cases of subdural hematoma found in this study.

This small study is an important one, evaluating a sample of college football players preseason and postseason by way of a clinical interview, eight neuropsychological measures, and a concussion symptom scale rating. Of 393 players, 34% had experienced one previous concussion and 20% had suffered two or more concussions. This study is unique in evaluating the presence of a learning disability and its relationship to concussion history. The study indicates that cognitive functioning in athletes is reduced with a history of multiple concussions and learning disability. There appeared to be a stronger effect for those with both learning disabilities and multiple concussions. This study raises the concern that the effects of concussion are long-lasting and impact future mental functions.

This article represents a special report generated by a group of specialists at the Concussion Workshop held in 1997 and sponsored by the American Orthopedic Society of Sports Medicine. It consists of a report of findings based on the current literature. There is so much information in this article, I will attempt to highlight some important beliefs with regard to the current state of knowledge about concussion; however, I recommend reading the entire article.

Metabolic Events

Immediately following concussion, there is a physiologic response that leads to an imbalance between energy demand, production and delivery. Specifically, there is an increase in the demand for glucose coupled with a decrease in cerebral blood flow. The increased glucose demand has been demonstrated using positron-emission tomography (PET) scanning. This increase in demand lasts for as little as a few days to as much as one week in some animal studies. It has been observed in humans that this period of hyperglycolysis lasts as long as two weeks and that metabolic depression may last as long as one year.

The reduction in cerebral blood flow has been linked to the vasoconstrictive effects of local endothelial accumulation of calcium. Studies indicate a two-fold increase in locally traumatized areas. Calcium mediates a cascade of events leading to vasoconstriction. In severe head injuries, it has been demonstrated that calcium channel blockers can reduce this reactionary vasoconstriction and increase cerebral blood flow.

The biggest difficulty at this time is tying together these physiologic events with patient signs and symptoms. The persistence of metabolic dysfunction may not manifest itself symptomatically; therefore, it is difficult to determine criteria for return-to-play, in particular, over days to weeks following injury.

Evaluation and Return-to-Play

Specific recommendations regarding evaluation and return-to-play criteria follow:

• Always check for subtle signs of fracture, with careful attention paid to palpation of the head and face and otologic evaluation of the ears.

• When asking about symptoms such as headache, dizziness, ringing in the ears, double vision, etc., recognize that many athletes minimize and under-report these symptoms in an attempt to get back into play.

• If signs and symptoms clear within 15 minutes, challenge the athlete with exertion and provocative position in an attempt to increase intracranial pressure. Examples include the 40-yard dash, five situps or pushups, or deep-knee bends. If symptoms return or appear, the athlete should not be allowed to return to play on that same day.

• Loss of consciousness precludes return to play.

• Symptoms that preclude return to play are dizziness; slowness in responding to questions; and memory loss - in particular, retrograde amnesia (loss of memory of events prior to the injury). In particular, caution should be exercised with retrograde amnesia, due to the observation that most athletes do not recover during the athletic event.

• Particular attention should be paid to younger athletes with a persistent or "new" headache following concussion.

• A strategy used by the Pittsburgh Steelers was recommended. It included the use of neuropsychologic testing before the beginning of the season to establish a baseline. Testing was then repeated at the time of head injury, within 24 hours after a suspected concussion, and again five days after injury.

• A standardized sideline evaluation tool was discussed: the Standardized Assessment of Concussion (SAC). Although not enough research has been conducted for the group to recommend its use, the group felt it was potentially a useful study tool. The SAC consists of a sequence of evaluation beginning with orientation, followed by: immediate memory; neurological screening (includes evaluation of amnesia; motor and sensory testing); concentration; exertional maneuvers; and delayed recall. Each element is scored and an overall score is generated. A copy of the form for the SAC is included as an appendix to the Wojtys et al. article.