Concussion

AMAA Journal,  Winter, 2005  by Robert S. Fawcett

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Case Presentation

You are the sideline doc at the conference championship football game. You are called to the field to examine your QB who was sacked in the last play of the first half with his head hitting the firm fall turf. He moves all extremities, has no neck pain, no loss of consciousness, but doesn't remember getting hit, the quarter, or who the opponent is. You walk him to the sideline and 15 minutes later his memory deficit is only for the play on which he was injured. What are other pertinent details to elicit on history and physical exam? Can he play again in that game?

Introduction

There have been three consensus conferences on concussion in sport. The first was convened almost 40 years ago, when the Congress of Neurologic Surgeons defined concussion as "a clinical syndrome characterized by the immediate and transient post-traumatic impairment of neural function such as alteration of consciousness, disturbance of vision or equilibrium, etc., due to brain stem dysfunction" (1). We still use this functional and clinical definition today, though other definitions have been proposed. The American Association of Neurology defines concussion as "any trauma induced alteration in mental status that may or may not include a loss of consciousness" (2).

In Vienna, Austria in 2001, the International Ice Hockey Federation, the Federation Internationale de Football, and the International Olympic Committee convened the 1st International Symposium on Concussion. Grading systems proposed by various researchers prior to the Vienna conference were called into question because they failed to serve as a reliable assessment of the severity of the injury. Severity seemed to correlate best with number and degree of concussion symptoms and how long those symptoms persisted. In the fall of 2004, the 2nd International Symposium convened in Prague, and issued guidelines that attempt to change significantly the way we handle athletes with concussion.

No Return

One of the most sweeping changes of the Prague document is that no player should be allowed to return to play in the same contest following a concussion. Even more stringent is the recommendation for a period of "cognitive rest" to limit activities of daily living and scholastic activity while symptomatic. The reason for this limitation is to avoid "second impact syndrome," a phenomenon originally described by Saunders and Harbaugh in 1984 (3), in which an athlete suffers a second concussion before recovering completely from the first. This can result in more varied, severe, and long lasting symptoms, even death, with the second impact, and those symptoms are often caused by minor impact. It is felt to result from loss of autoregulation to the intracranial blood supply, sometimes resulting in increased intracranial pressure and possible herniation (4).

Age

One of the key pieces of information lacking in the case described is the age of the player. Though no age limits are included in the Prague guideline, it is clearly most applicable in the pediatric age group, based on studies showing lower age groups being at increased risk of damage or prolonged recovery from head injury (4), (5), (6), (7). In fact, there have been no clearly defined cases of "second impact syndrome" in the adult athlete in sports other than boxing (8).

Prior History

McCrea, Guskiewicz, and others have shown conclusively that athletes with prior history of completely recovered concussion are more likely to undergo subsequent concussion (9), (10), and subsequent concussions are likely to be more severe. In our case above, consideration of the athlete's prior history would be of great importance in attempting to assess future risk.

Mechanism of Injury

A blow to a stationary but moveable head causing sudden acceleration tends to produce maximum injury to the brain immediately beneath the point of impact--a "coup" injury. A blow to a moving head causing immediate deceleration causes damage opposite the point of impact--a "contrecoup" injury. Neither of these mechanisms predicts prognosis. It is known, however, that blows causing rotation of the brain produce shearing forces, which are tolerated more poorly than either coup or contrecoup injury (11).

Symptoms and Signs

Though loss of consciousness may be the most attention-getting symptom of concussion, it is neither the most common nor the most serious. Headache, seen in up to 85% of concussed athletes, is the most common symptom. Amnesia, according to Lovell and colleagues (12), (13), is most predictive of a prolonged neurocognitive deficit. Other symptoms include nausea, double or blurred vision, dizziness, fatigue, feeling foggy or sluggish, and difficulty with concentration.

The athlete may appear slightly dazed, be slow to answer questions or to respond to teammates. Amnesia for the event itself is very frequent, but may include inability to remember the score, the opponent, the location of the game, or getting to the sidelines after the injury. The athlete should undergo frequent reassessment on the sidelines to assure that there is no deterioration, and the helmet or other essential equipment should be kept by the medical team to assure that the athlete does not return to play.