How Do You Know If You Have a Concussion?
A clear explanation of concussions, what happens inside the brain after a hit to the head, and how doctors evaluate and treat them
A Moment in the ER
Jason, a 17 year old linebacker, walks into the emergency department holding his helmet. He says he took a hard hit during a tackle and felt dizzy immediately afterward. For a moment he could not remember the last play of the game.
Now he has a headache and says everything feels a little “foggy.”
Some head injuries leave obvious signs. Others quietly affect how the brain works.
What a Concussion Actually Is
A concussion is a mild injury to the brain caused by sudden movement inside the skull.
The brain is soft and suspended in fluid inside the skull. When the head experiences a sudden impact or rapid acceleration, the brain can briefly shift or rotate within that space. That movement disrupts how brain cells communicate with each other.
Doctors sometimes describe this as the brain being “shaken.” In most concussions there is no visible bleeding or structural damage on imaging. The injury is functional. The brain’s signaling temporarily stops working the way it should.
Why Symptoms Can Feel So Strange
Concussions affect how the brain processes information.
Patients often describe a feeling of mental fog. Headaches, dizziness, nausea, and sensitivity to light or noise are common. Some people notice difficulty concentrating or remembering recent events.
Experienced emergency physicians know that concussions can look subtle at first. A patient may appear physically fine, but small changes in memory, reaction time, or balance suggest that the brain’s communication network has been disrupted.
The More Serious Injuries Doctors Must Rule Out
Not every head injury is a simple concussion.
When someone hits their head, doctors must consider more dangerous possibilities. These include skull fractures, bleeding inside the brain, or swelling that can place pressure on brain tissue. Patients taking blood thinners have a higher risk of these complications.
That is why doctors ask careful questions and perform a neurological exam. If symptoms are concerning, a CT scan may be performed to look for bleeding or fractures. In the emergency department, CT is usually the fastest and most reliable test to rule out dangerous head injuries.
Why Rest Helps the Brain Recover
Most concussions improve with time and rest.
The brain needs a period of reduced stimulation to restore normal signaling. This usually means avoiding intense physical activity, limiting screen time, and getting adequate sleep. Many patients also benefit from staying in quieter environments and avoiding bright light for a short time.
Repeated concussions are the bigger concern. While the brain can recover from a single mild injury, repeated trauma over time can cause cumulative damage. That is why athletes are often advised to rest fully and avoid returning to sports until symptoms have resolved.
THE BOTTOM LINE
• A concussion is a mild brain injury caused by sudden movement or impact that disrupts normal brain signaling
• Symptoms can include headache, dizziness, confusion, memory problems, and sensitivity to light or noise
• Most concussions improve with rest and time, but doctors must first rule out more serious injuries such as brain bleeding or skull fractures
By Dr. Karim Ali. Emergency Physician