Whether from a minor car accident to a game of flag football, concussions are surprising common.

Concussions occur whenever the brain moves or shifts within the skull, usually due to some kind of force. You might get a concussion when your car is rear-ended and your head snaps forward from the momentum or you hit your head during a fall.

They’re surprisingly common, especially in sports, and have lately become a hot topic within professional football — the latest numbers show that 60 percent of players have had at least one concussion. Research now reveals that they might carry more of a risk than previously thought, especially when it comes to your risk of stroke.

Concussions can be tough to identify. After all, smack your head on a low ceiling and you might just shake it off. But there are certain symptoms that set it apart.

These symptoms fall into four categories: thinking and remembering, physical, emotional and moods, and sleep. The symptoms of thought include difficulty concentrating or feeling slowed down while thinking, while physical signs involve headache, blurry or fuzzy vision, dizziness and sensitivity to light and noise. As for emotions, be on the lookout for irritability and sadness. Sleep changes may include sleeping more than usual, less than usual or having trouble falling asleep.

These symptoms are only temporary, and if it’s your first concussion, you may not even notice them. Still, they’re worth keeping in mind because the best way to recover from any sort of traumatic brain injury (including a concussion) is to rest — think plenty of sleep, avoiding physically demanding activities, taking a break from contact or recreational sports, and easing slowly back into normal activities.

Avoiding multiple concussions is key because over time, concussions can increase your risk of stroke. According to Jonathan J. Russin, MD, an assistant professor of clinical neurological surgery and assistant surgical director of the USC Neurorestoration Center at Keck School of Medicine at USC, several studies link concussions to an increased risk of stroke. The exact mechanism between the two is still unclear, but experts have a few theories.

“One is that the traumatic brain injury disturbs the brain’s ability to auto-regulate blood flow,” said Dr. Russin, who also is a neurosurgeon at Keck Medicine of USC. “Another is that the traumatic injury results in microthrombi within blood vessels inside the brain.” (Microthrombi is the formation of tiny — hence micro — blood clots.)

As for brain cancer, there’s good news: The most comprehensive (and long-term) study on the topic found little evidence that a traumatic brain injury could cause a brain tumor — and if the risk exists, it’s extremely small.

There’s no way to undo a traumatic brain injury, according to Dr. Russin, so your best bet is to avoid concussions altogether. That means wearing a helmet, sitting out of contact sports, not driving when under the influence of alcohol or drugs and wearing a seatbelt in any moving vehicle. After all, it’s better to be safe than sorry.

By Deanna Pai

If you’re in Southern California and you’ve suffered from multiple concussions, make an appointment with one of our neurologists. To schedule an appointment, call (800) USC-CARE (800-872-2273) or visit keckmedicine.org/request-an-appointment.