Football season is upon us again, so it’s time to think about sports injuries. We frequently have children admitted to the PICU (or to what we call the intermediate or step-down unit) for observation, typically overnight, who have struck their head. They have had concussions. What is a concussion, and what does it mean for the child?
The term itself is centuries old, but even thirty-five years ago, when I was in training, the actual definition of concussion was a bit vague. What was usually meant was that the patient got hit on the head and either lost consciousness briefly or at least wasn’t quite himself for some period of time afterward. These days we’re more precise than that, but concussion is still a somewhat inexact term. This is mainly because of our ignorance of the subtleties of how the brain works.
The formal definition of concussion is a transient interruption in brain function. By implication, various scans of the brain, such as CT scans or MRI scans, show no abnormalities. Since all the imaging studies are normal, defining concussion is necessarily inexact. I’m sure one day we’ll have some kind of machine that detects the reason for the symptoms of concussion, but right now we don’t have such a thing — concussion is an entirely clinical diagnosis, meaning there’s specific no test for it.
There are several systems for grading concussions. Here’s how the American Academy of Neurology grades their severity:
Grade I: confusion, no loss of consciousness, symptoms last for < 15 minutes, has memory of the event
Grade II: confusion, may lose memory of the event but no loss of consciousness, symptoms last for > 15 minutes
Grade III: loss of consciousness and no memory of the event
The list of symptoms that can come from a concussion is a long one. Headache, dizziness, vomiting, and ringing in the ears are common. Various behavioral changes are also common, such as lethargy, difficulty concentrating, and irritability.
What are the effects of concussion on a child? Years ago we pooh-poohed the idea that mild concussions cause brain problems. For example, football players were sent right back into the game after experiencing a concussion. We now know that is dangerous. As a general rule, we don’t recommend any contact sports for at least a week (some authorities say longer) after all symptoms have cleared. This is because a repeat blow to the head, even a very mild one, can cause severe injury to a brain that has not fully recovered from the last injury.
What about long term effects of concussions? The overwhelming majority of children who suffer a concussion, especially a mild one, recover completely. But around a fifth or so of children who have had severe concussions continue to have problems many months afterward.
You can read much more about concussions at this site, from the federal Centers for Disease Control, this one, from the Mayo Clinic, and this one, from the respected Brain Trauma Foundation.
I’ve written before about traumatic brain injuries in children. These sorts of injuries are frustratingly common — I’ve just seen several new ones. Although we’ll never eliminate them, there are many ways to reduce both their number and the severity of those that do occur. These ways are well known and extremely low-tech. Since car accidents are the leading cause of them in children, that is where we can really have an effect.
A small child who is unrestrained by a car seat is particularly likely to have a severe brain injury if involved in an accident, and that accident need not be at highway speeds. These days more and more parents know how to use car seats for their infants and toddlers, and over the past decade I’ve seen fewer and fewer injuries to unrestrained small children.
What I continue to see, however, are teenagers who are out by themselves, away from their parents, and don’t use a seat belt. The result is they are ejected from the car after impact, and this raises enormously the risk of severe brain injury. I’ve just seen yet another such case.
The most severe injuries come from what we call diffuse axonal injury, or shear injury. This injury results from the brain being jarred suddenly inside the skull, often with a bit of rotational effect. We call it shear injury because the force of impact shears apart the delicate wiring bundles that connect the nerve cells to one another. Most children recover to some extent, but some degree of permanent damage is common.
If you are interested in learning more about traumatic brain injury, the Brain Trauma Foundation is an excellent place to start.
Most children with significant brain injury spend time in a PICU. Like most experienced pediatric intensivists, I have seen hundreds of these children over the years, with dozens at least in the severe category. In one sense the term “traumatic brain injury” has limited usefulness because it covers such a wide range of injuries, from mild concussions to more extensive injury, to lethal damage. In another sense, however, it is a very useful diagnostic category because the brain responds to a wide variety of injuries in a very similar, stereotypic way.
Our understanding of the manifestations of TBI has grown over the years considerably. When head CT scans became available we could for the first time assess such things as bleeding inside the skull or swelling of the brain easily and safely. I remember how exciting it was in 1974 to see the first simple CT images taken on grainy Poloroid snapshots. Now we have sophisticated computer reconstructions of the brain. The technology represented such a breakthrough that its inventors received the Nobel Prize for it.
We soon realized, however, that some injuries to the brain, particularly what we call shear injury, are not well seen on CT — it takes an MRI scan to do that. We also came to realize that the most important thing we could do in the PICU for a child with severe TBI was to make sure the injury did not get worse: simple supportive measures like relieving pain and keeping the heart and lungs working well were key supportive measures to use while we waited for the child’s brain to heal.
Increasing understanding of milder forms of TBI have made us realize it is much more common than we once thought. For children, although the long-term outcome for mild to moderate TBI is good, persistent problems with such things as headache, mood changes, and difficulties in school are not uncommon, and these can last for months. There is a great deal of information available about TBI. There are many misconceptions about it, too. You can find authoritative, respected advice from the National Institutes of Health here and from the Brain Trauma Foundation here, and many more useful links here.