Overview
A concussion is a mild traumatic brain injury that affects brain function. Effects are often short term and can include headaches and trouble with concentration, memory, balance, mood and sleep.
Concussions usually are caused by an impact to the head or body. However, not everyone who experiences a blow to the body or head has a concussion.
Some concussions cause the person to lose consciousness, but most do not.
Falls are the most common cause of concussions in adults and very young children. In children and teenagers, concussions are common among athletes who play a contact sport, such as American football or soccer. Most people recover fully after a concussion.
Symptoms
The symptoms of a concussion can be subtle. Symptoms may occur right away or in the hours and days after an injury. Symptoms can last for days, weeks or even longer.
Common symptoms after a mild traumatic brain injury are headache, confusion and loss of memory, known as amnesia. The person may forget the event that caused the concussion.
Physical symptoms of a concussion may include:
- Headache.
- Ringing in the ears.
- Upset stomach.
- Vomiting.
- Fatigue or drowsiness.
- Blurry vision.
Other symptoms of a concussion include:
- Confusion or feeling as if in a fog.
- Amnesia surrounding the event.
- Dizziness.
A witness may observe these symptoms in the person with a concussion:
- Temporary loss of consciousness, though this doesn't always occur.
- Slurred speech.
- Delayed response to questions.
- Dazed appearance.
- Forgetfulness, such as asking the same question over and over.
Some symptoms of a concussion occur right away. But sometimes symptoms may not occur for days after the injury, such as:
- Trouble with concentration and memory.
- Irritability and other personality changes.
- Sensitivity to light and noise.
- Trouble with sleep.
- Feeling emotional or depressed.
- Changes in taste and smell.
Symptoms in children
Concussions can be hard to recognize in infants and toddlers because they can't describe how they feel. Concussion clues may include:
- Dazed appearance.
- Lack of interest and tiring easily.
- Irritability and crankiness.
- Loss of balance and unsteady walking.
- Crying more than usual.
- Change in eating or sleeping patterns.
- Lack of interest in favorite toys.
- Vomiting.
When to see a doctor
See a healthcare professional within 1 to 2 days if:
- You or your child experiences a head injury, even if emergency care isn't required.
Children and adolescents need to see a healthcare professional trained in evaluating and managing pediatric concussions.
Seek emergency care for an adult or child who experiences a head injury and any of these symptoms:
- Repeated vomiting or upset stomach.
- A loss of consciousness lasting longer than 30 seconds.
- A headache that gets worse over time.
- Fluid or blood draining from the nose or ears.
- Vision or eye changes. For example, the black parts of the eyes, known as the pupils, may be bigger than usual or not equal sizes.
- Ringing in the ears that doesn't go away.
- Weakness in the arms or legs.
Also seek emergency care for any of these symptoms:
- Changes in physical coordination, such as stumbling or clumsiness.
- Serious changes in behavior.
- Confusion or disorientation. For example, the person may not recognize people or places.
- Slurred speech or other changes in speech.
- Obvious changes to mental function.
- Seizures or convulsions.
- Dizziness that doesn't go away or that goes away and comes back.
Also watch for and seek emergency care for symptoms that worsen over time and for large head bumps or bruises, such as bruises around the eyes or behind the ears. It's especially important to seek emergency care if these symptoms appear in infants under 12 months of age.
When symptoms occur in athletes
Never return to play or vigorous activity right after a concussion or on the same day as an injury. This is true even if a concussion is suspected. Also don't do any activities that can put you at risk of another concussion. Depending on your symptoms, you may need to gradually return to learning and physical activity. The steps you take to get back to your typical routine should always be supervised by a healthcare professional.
Causes
A concussion is caused by an event that affects your brain. During a concussion, the brain slides back and forth against the inner walls of the skull. This can be due to a violent blow to the head and neck or upper body. It also may be caused by the sudden acceleration or deceleration of the head. This may happen during a car crash, a fall from a bike or from a collision with another player in sports.
These movements injure the brain and affect brain function, usually for a brief time. Sometimes a traumatic brain injury can lead to bleeding in or around the brain, causing prolonged drowsiness, confusion and, sometimes, death. Anyone who experiences a brain injury needs to be monitored in the hours afterward and seek emergency care if symptoms worsen.
Risk factors
Events and factors that may increase the risk of a concussion include:
- Activities that can lead to falls, especially in young children and older adults.
- High-risk sports such as American football, hockey, soccer, rugby, boxing or other contact sports.
- Not using proper safety equipment or not having supervision when playing high-risk sports.
- Auto accidents.
- Pedestrian or bicycle accidents.
- Military combat.
- Physical abuse or assault.
A previous concussion also increases the risk of having another.
Complications
Potential complications of concussion include:
- Post-traumatic headaches. Some people have headaches for several days to weeks after a brain injury.
- Post-traumatic vertigo. Some people experience a sense of spinning or dizziness for days or weeks.
- Persistent postconcussive symptoms, also known as postconcussion syndrome. Some people may have symptoms that last longer than expected. These symptoms may include headaches, dizziness and trouble with thinking. If they last longer than three months, they're called persistent postconcussive symptoms.
- Effects of multiple brain injuries. Researchers are studying the effects of repeated head injuries. At this time, the evidence that repeated concussions have long-term effects is mixed. Some studies suggest that former athletes in contact sports are at higher risk of developing trouble with brain function and mental health later in life. However, other studies suggest that the development of trouble with brain function and mental health in athletes in contact sports may be more strongly related to other factors.
- Second impact syndrome. This rare but potentially fatal syndrome involves rapid brain swelling that occurs when a person has a second head injury before fully recovering from a first injury. It is important that athletes suspected of having a concussion be removed from play right away and not return until they have recovered.
Prevention
These tips may help you prevent or minimize the risk of a concussion:
- Wear protective gear during sports and other activities. This includes a helmet when bicycling, motorcycling, snowboarding or doing any activity that may result in a head injury. Make sure the equipment fits properly, is well maintained and is worn correctly.
- Buckle your seat belt. Wearing a seat belt may prevent a head injury during a traffic accident.
- Make your home safe. Keep your home well lit and your floors free of items that can lead to trips and falls. Falls around the home are a leading cause of head injury.
- Protect young children. To help lessen the risk of head injuries in children, block off stairways and install window guards.
- Exercise regularly. Exercise strengthens your leg muscles and improves your balance. This can help prevent falls.
- Educate others about concussions. Educate coaches, athletes, parents and others about concussions to help spread awareness. Athletes should not return to play on the same day if a concussion is suspected or confirmed.