If you're having difficulty understanding what a brain concussion is, and how your son or daughter's head-injury affects their further participation in sports, then you're in good company. The nature and effects of concussions are still poorly understood by many athletes, parents, coaches, news reporters and, to a certain extent, even the medical community. But because the brain is a treasured organ" ?one that athletes should want to keep in good working order for the rest of their lives" ?a good understanding of concussions is crucial.

Neurologists and neurosurgeons cringe when they hear sports-reporters make comments like, "Johnny had a CAT scan and it showed that he didn't have a concussion." The truth is that CAT scans don't show concussions. They do show other serious consequences of head injuries, like bleeding within the brain, or hemorrhages that compress the brain. But concussions" ?while no less real" ?are invisible to brain-imaging tests like CAT scans and MRIs.

So what is a concussion? If a blow to the head caused unconsciousness, a concussion occurred. Most people know this. But a concussion can occur even when there is no loss of consciousness. Other symptoms after a head-injury indicating a concussion include:

1. impaired attention, e.g. vacant stare, slowness to respond, easy distractibility
2. slurred speech, or speech that doesn't make sense
3. clumsiness or unsteadiness
4. disorientation, e.g. walking in the wrong direction, forgetting the day of the week
5. excessive emotional reaction, e.g. easy tears, overly upset
6. memory impairment, e.g. asking same question repeatedly, can't memorize new facts

Other symptoms can develop hours or even weeks after the injury, including headache, dizziness, poor concentration, irritability, impaired memory, fatigue, disrupted sleep, anxiety, depression, and a lack of good judgment or insight.

You'll notice that all these symptoms share a common feature" ?an alteration in brain function. The normal brain processes, which depend on proper signaling among the brain's 20 billion brain cells, are out of whack.

There can also be physical damage to the brain's cells. Because brain-cells are so tiny, brain scans don't detect them. Injuries causing more severe concussions can tear apart the cells' axons (the long filaments that carry coded messages over long distances within the brain). As you can imagine, these rips in the very fabric of the brain can cause lasting impairments in brain function or require long periods of time for recovery.

One certainty about sports-related concussions is that they are very frequent. The Centers for Disease Control estimates there are at least 300,000 of them in the U.S. per year and they comprise about 20% of all head injuries. Research also indicates that the brains of high school athletes are more vulnerable to concussion than those of older athletes, and require longer periods of time to fully recover.

Individuals who have had one concussion are at greater risk for another. For example, in one study of high school and college football players, concussions occurred about six times more frequently in student-athletes who had experienced prior concussions than in those who had not. Moreover, repeated concussions can have more severe outcomes than first concussions.

A rare but particularly scary phenomenon has been called the "second impact syndrome" in which a second concussion occurring within days or weeks of an earlier concussion can produce catastrophic consequences" ?including death" ?way out of proportion to the apparent severity of the re-injury.

Because of the potentially serious consequences, athletes, coaching staffs and parents need to have a heightened awareness of head-injuries and their need for proper evaluation, including by medical personnel. Various guidelines have been created for decisions about when it is safe to resume participation in contact sports. These guidelines, while based more on expert opinion than on medical evidence, are still the best benchmarks we have until more studies are done.

All guidelines agree that an athlete needs to become symptom-free in all areas" ?thinking, memory, emotions, coordination, balance, etc." ?before resuming play. After a first concussion, the athlete should have been normal for at least a week, and after a second concussion, for probably two weeks.

When should an athlete hang up his or her cleats and retire from the sport? How many concussions are too many? No one has a definite answer to either question. As Clint Eastwood's "Dirty Harry" might ask, "Are you feeling lucky?" Three concussions in the same season" ?or even in an entire sports career" ?should certainly raise concern about long-term damage to the brain.

Of course, student-athletes often pressure their parents to allow them to return to play sooner than might be wise. In these circumstances it is useful to recall that many professional athletes in football, hockey, boxing and other sports have retired from their lucrative careers rather than suffer additional concussions. If these high-profile individuals were willing to give up their big paydays in order to protect their brains, then perhaps your son or daughter will be able to follow their examples when less money is at stake. However, if you are the parent and are being pressured to allow an early return to play, you just might have to stand tall, do the right thing, and say no.

For more information about traumatic brain injury see the websites of The Brain Matters and The Brain Injury Association of America.

(C) 2005 by Gary Cordingley