By David Alden-St.Pierre, MS, PA-C, Illustration by Molly Feuer
You’re on the ground. You’re not sure why. There are a few people standing around you, talking to you, talking about you. Someone keeps asking if you’re okay, but you don’t know how to answer. Why are you on the ground? What happened? Are you hurt?
If this scenario is familiar, you may have had the unfortunate experience of crashing so hard that you lost consciousness. Most of the time a young, healthy person can recover and live to ride another day. Rarely, a bike crash will involve a brain injury severe enough to require life-long rehabilitation. There is a dangerous grey area between no lasting effects and significant injury called mTBI: minor traumatic brain injury. These minor injuries are very common and vastly under-reported. And, research is starting to indicate that these “minor” injuries are not so minor, so it’s becoming more and more important to recognize the signs and symptoms.
You may be thinking, “I always wear my helmet, I’ll be fine.” And helmets are very important, but some of the internal injuries the brain can sustain can’t be prevented with today’s helmets. Here’s why: the brain sits inside the skull, tethered at the bottom by the spinal cord and surrounded by fluid called cerebrospinal fluid. The brain can move within the skull, and if the head sustains a hard enough impact, the brain can essentially bounce around in the skull. A simple way to envision this is to imagine an egg. The yolk can be whole within the shell, but if you shake the egg violently, the yolk could be disrupted while the external shell is intact. For the brain, an initial impact can cause damage to one side of the brain (the front, for example if you landed on your forehead), and there can be damage to the opposite side from reactive forces.
Sometimes evidence of this can be found on imaging (CT scans or MRI), as cerebral contusions (just like bruises you can find anywhere else on the body). More often the damage is microscopic and is not easily detectable.
So you’ve crashed, you hit your head, now what do you do? In a perfect world, you’re whisked to the closest emergency department on a backboard with cervical spine precautions in place, because a fall from about two meters (or six feet for Americans who refuse to use the metric system) is enough to raise concern for an injury to the cervical spine. Add some speed to the equation and that concern goes up. Paralysis is no joke: there have been stories of people walking in to emergency departments and having unstable neck fractures discovered. Not everyone needs X-rays or other imaging studies to rule out a fracture, but being evaluated by a professional is advisable.
If we can, for the sake of this article, assume that the neck is fine, we’ll focus on the head. Serious injuries shouldn’t be a common concern for most mountain bikers because they mostly occur in older people or at high speeds. Serious brain injuries are also easier to identify because, well, they’re serious. Fractured skulls and intracranial bleeds aren’t the things that a rider will just “shake off.” For riders who will hit the high speeds associated with serious head injuries, full face helmets before a crash and neck immobilization after a crash are critical.
Big crashes aside, mTBI injuries are the type of injuries that a rider might say, “yeah, I’m okay, just a little shaken up.” Maybe he or she is a bit dizzy or nauseated for a couple of minutes, maybe not. The term concussion is used quite frequently, but the definition of a concussion is not as clear as many would think it is. The easiest way to define a concussion is that it is a head injury associated with any transient neurologic deficit— anything from loss of consciousness to confusion or memory lapse (“what happened?”) to blurred vision—lasting seconds to minutes after blunt trauma.
If you crash, hit your head and have any associated symptoms, even subtle ones (slow to answer questions, a little incoordination, etc.), you should be checked out by a medical provider. You may not need any imaging studies, but you should have the event documented. While most people will not have any problems after the initial crash, some people may develop posttraumatic seizures. These usually happen early, within the first 24 hours after the injury, but can happen up to a week later. Aside from seizures, another entity called Post-Concussive Syndrome (PCS) can develop.
The symptoms of PCS can be as vague and non-descript as those of a concussion. They include headaches, anxiety, restlessness, sleeping problems, difficulty concentrating and irritability. That reminds me of my college years…
Seriously though, PCS can occur even with the mildest concussions and can linger for months. The big question the medical community is dealing with is what to do with someone after they’ve suffered a mild TBI and have PCS symptoms. There are no clear treatments or medications. Even old recommendations such as waking a person up every few hours after a concussion are uncertain.
One thing that is certain: Brain injuries, even mild ones, have an additive effect. Lots of research is geared towards sports such as football and boxing—sports where head injuries are part of routine play—and evidence is pointing to cumulative head and brain trauma as a cause of early dementia and a drop in IQ. Even more research is being done on soldiers returning from war zones, and eventually we might have a handle on this problem. But for now, we do know that the more you hit your head, the more likely you are to suffer long term problems with cognition and even personality changes.