A concussion is an injury to the brain that results in temporary loss of normal brain function. Medically, it is defined as a clinical syndrome characterized by immediate and transient alteration in brain function, including alteration of mental status or level of consciousness, that results from mechanical force or trauma.
Concussions can be caused by direct trauma to the head, such as from falling, getting hit or being in an accident. They can also occur as a result of rapid acceleration-deceleration of the head, such as in whiplash injuries or blast injuries, like in a war zone. Many people assume that concussions involve passing out or a loss of consciousness, but this is not true. In many cases, people with a concussion never lose consciousness. In several cases, external signs of head trauma, such as bleeding, may also be absent.
A concussion can affect memory, judgment, reflexes, speech, balance and muscle coordination. People with concussions often report a brief period of amnesia or forgetfulness, where they cannot remember what happened immediately before or after the injury. They may act confused, dazed or describe “seeing stars.” Paramedics and athletic trainers who suspect a person has suffered a concussion may ask the injured person if they know their name, what month/year it is and where they are.
Even mild concussions should not be taken lightly. Neurosurgeons and other brain injury experts emphasize that although some concussions are less serious than others, there is no such thing as a minor concussion. In most cases, a single concussion should not cause permanent damage. A second concussion soon after the first one does not have to be very strong for its effects to be permanently disabling.
Common Symptoms of Concussion
- Vision disturbances (double or blurry vision)
- Dizziness or imbalance
- Nausea or vomiting
- Memory loss
- Ringing ears
- Difficulty concentrating
- Sensitivity to light
- Loss of smell or taste
- Trouble falling asleep
If any of these occur after a blow to the head, a health-care professional should be consulted as soon as possible.
Most people will recover quickly and completely following a concussion. Some people can have symptoms that last for several weeks before gradually getting better. Seek immediate medical attention if:
- Headache is worse or does not go away
- Slurred speech, weakness, numbness or decreased coordination
- Significant nausea or repeated vomiting
- Loss of consciousness
- Inability to wake up
- Symptoms have worsened at any time
- Symptoms have not gone away after 10-14 days
- History of multiple concussions
Brain imaging studies with MRI and CT scans should not be performed routinely in the diagnosis of concussions. They typically do not show any significant changes and, with CT scans, expose individuals to unnecessary radiation. While such tests are more useful for identifying structural defects, an injury from concussion is metabolic and microscopic in nature that often presents normally on neuroimaging.
The doctor asks a variety of questions about how the injury occurred, where on the head and what symptoms are shown. The patient should report any unusual experiences to the health care provider.
According to the Centers for Disease Control and Prevention (CDC) surveillance report of traumatic brain injuries, about 2.87 million TBI-related ED visits, hospitalizations and deaths occurred in the United States in 2014. Each year, more than 800,000 children are treated for TBI at emergency departments in the U.S. The highest incidence of TBI occurred in people over the age of 75, children aged 0-4 years and individuals aged 15-24 years.
University of Pittsburgh's Brain Trauma Research Center reports more than 300,000 sports-related concussions occur annually in the U.S. Additionally, the likelihood of suffering a concussion while playing a contact sport is estimated to be as high as 19% per year of play; in other words, almost all athletes of contact sports suffer from a concussion within five years of participation. It has been reported that more than 62,000 concussions are sustained each year in high school contact sports. Among college football players, 34% have had one concussion and 20% have endured multiple concussions. Estimates show that 4-20% of college and high school football players sustain a brain injury over the course of one season. The risk of concussion in football is three to six times higher in players who have had a previous concussion.
A study conducted by McGill University in Montreal found that 60% of college soccer players reported symptoms of a concussion at least once during the season. The study also reveals that concussion rates in soccer players were comparable to those in football. According to this study, athletes who suffered a concussion were four to six times more likely to suffer a second concussion. Research such as this has led to greater interest in developing protective headgear for soccer participants, but it is not clear that such headgear actually reduces the risk of concussion.
Concussion symptoms can affect people in a variety of ways, including vision, balance and even mood. Historically, the standard treatment for concussion was to get plenty of rest. However, newer approaches involve therapy to target specific symptoms. Clinics exist that help determine the most affected system and appropriate therapy for a given symptomology. In addition, a thorough medical examination may be needed before returning to sports or activities with the potential for contact or further head injury.
Following a concussion, some people may suffer persisting symptoms, such as memory and concentration problems, mood swings, personality changes, headache, fatigue, dizziness, insomnia and excessive drowsiness for several weeks to months. This is known as post-concussive syndrome. Patients with post-concussive syndrome should avoid activities that put them at risk for a repeated concussion. Athletes should not return to play while experiencing these symptoms. Athletes who suffer repeated concussions should consider ending participation in the sport.
Second impact syndrome results from acute and often fatal brain swelling that occurs when a second concussion is sustained before complete recovery from a previous concussion. The impact is thought to cause vascular congestion and increased intracranial pressure, which can occur very rapidly and may be difficult or impossible to control. The risk of second-impact syndrome is higher in sports like boxing, football, ice or roller hockey, soccer, baseball, basketball and skiing. The CDC reports an average of 1.5 deaths per year from sports concussions. In most cases, a concussion, usually undiagnosed, had occurred prior to the final one.
Buy and use helmets or protective headgear approved by the American Society for Testing and Materials (ASTM) for specific sports 100% of the time. The ASTM has vigorous standards for testing helmets for many sports; helmets approved by the ASTM bear a sticker stating this. Helmets and headgear come in many sizes and styles, and must properly fit to provide maximum protection against head injuries. In addition to other safety apparel or gear, helmets or headgear should be worn at all times for:
- Baseball and softball (when batting)
- Horseback riding
- Powered recreational vehicles
Headgear is recommended by many sports safety experts for:
- Martial arts
- Pole vaulting
- Supervise younger children at all times, and do not let them use sporting equipment or play sports unsuitable for their age.
- Do not dive in water less than nine feet deep or in above-ground pools.
- Follow all rules at water parks and swimming pools.
- Wear appropriate clothing for the sport.
- Do not wear any clothing that can interfere with vision.
- Do not participate in sports when ill or very tired.
- Obey all traffic signals, and be aware of drivers when cycling or skateboarding.
- Avoid uneven or unpaved surfaces when cycling or skateboarding.
- Perform regular safety checks of sports fields, playgrounds and equipment.
- Discard and replace sporting equipment or protective gear that is damaged.
- Wear a seat belt every time, whether driving or riding in a motor vehicle.
- Never drive while under the influence of drugs or alcohol, or ride as a passenger with anybody who is under the influence.
- Keep unloaded firearms in a locked cabinet or safe, and store ammunition in a separate, secure location.
- Remove hazards in the home that may contribute to falls. Secure rugs and loose electrical cords, put away toys, use safety gates and install window guards. Install grab bars and handrails for the frail or elderly.
The skull protects the brain against penetrating trauma, but does not absorb all the impact of a violent force. The brain is cushioned inside the skull by the surrounding cerebrospinal fluid. Despite this, an abrupt blow to the head, or even a rapid deceleration, can cause the brain to contact the inner side of the skull. There is a potential for tearing of blood vessels, pulling of nerve fibers and bruising of the brain.
Sometimes the blow can result in microscopic damage to the brain cells without obvious structural damage visible on a CT scan. In severe cases, the brain tissue can begin to swell. Since the brain cannot escape the rigid confines of the skull, severe swelling can compress the brain and its blood vessels, limiting the flow of blood. Without adequate blood flow, the brain does not receive the necessary flow of oxygen and glucose. A stroke can occur. Brain swelling after a concussion has the potential to amplify the severity of the injury.
A blow to the head can cause a more serious initial injury to the brain. A contusion is a bruise of the brain tissue involving bleeding and swelling in the brain. A skull fracture occurs when the bone of the skull breaks. A skull fracture by itself may not necessarily be a serious injury. Sometimes, however, the broken skull bones cause bleeding or other damage by cutting into the brain or its coverings.
A hematoma is a blood clot that collects in or around the brain. If active bleeding persists, hematomas can rapidly enlarge. Like brain swelling, the increasing pressure within the rigid confines of the skull (due to an enlarging blood clot) can cause serious neurological problems, and can even be life-threatening. Some hematomas are surgical emergencies. Hematomas that are small can sometimes go undetected initially, but may cause symptoms and require treatment several days or weeks later.
Warning Signs of a Serious Brain Injury
- Pain: Constant or recurring headache
- Motor dysfunction: Inability to control or coordinate motor functions or disturbance to balance
- Sensory: Changes in ability to hear, taste or see; dizziness; hypersensitivity to light or sound
- Cognitive: Shortened attention span; easily distracted; overstimulated by environment; difficulty staying focused on a task, following directions or understanding information; feeling of disorientation, confusion and other neuropsychological deficiencies
- Speech: Difficulty finding the "right" word; difficulty expressing words or thoughts; dysarthric speech
Seek immediate medical attention if any of these warning signs occur
Because each player and each concussion is unique, there is no set timeframe for recovery and return to participation under the NFL’s current guidelines. The decision to return a player who has a concussion back to practice and games resides with the team physician managing the concussion protocols and is confirmed by an independent neurological consultant (INC), who is consulted specifically for the player’s neurological health.
After a player is diagnosed with a concussion, the protocol calls for a minimum of daily monitoring. The player’s past concussion exposure, medical history and family history are considered, creating a more complete picture of his health. The protocol progresses through a series of steps, moving to the next step only when all activities in the current step are tolerated without recurrence of symptoms. Communication between the player and the medical staff during the protocol is essential.
The first step is rest. During this time, in addition to avoiding physical exertion, the player is to avoid electronics, social media and even team meetings until he returns to his baseline level of signs and symptoms. The next step introduces light aerobic exercise, which takes place under the direct oversight of the team’s medical staff. If aerobics are tolerated, the team physician will reintroduce strength training. The fourth step includes some non-contact football-specific activities, and the fifth step, which is clearance to resume full football activity, comes only after neurocognitive testing remains at baseline and there is no recurrence of signs or symptoms of a concussion.
When the team physician gives the player final clearance, the player has a final examination by the INC assigned to his team. As part of this examination, the INC will review all reports and tests documented through the player’s recovery. Once the INC confirms the conclusion of the team physician, the player is considered cleared and is eligible for full participation in the next game or practice.
This protocol allows for players to heal at their own individual rates, includes the expertise of both the team physicians and a neurological consultant and specifically includes an assessment of not only the most recent concussion, but also takes into account the medical history of the player.
The National Collegiate Athletic Association (NCAA) 2011-2012 Sports Medicine Handbook includes a section called "Concussion or Mild Traumatic Brain Injury (mTBI) in the Athlete," which notes:
"In the years 2004 to 2009, the rate of concussion during games per 1,000 athlete exposures for football was 3.1; for men's lacrosse, 2.6; for men's ice hockey, 2.4; for women's ice hockey, 2.2; for women's soccer, 2.2; for wrestling, 1.4; for men's soccer, 1.4; for women's lacrosse, 1.2; for field hockey, 1.2; for women's basketball, 1.2; and for men's basketball, 0.6, accounting for between four and 16.2% of the injuries for these sports, as reported by the NCAA Injury Surveillance Program by the Datalys Center."
The NCAA defines concussion or mild traumatic brain injury as "a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces."
The handbook also states, "NCAA member institutions must have a concussion management plan for their student-athletes on file with specific components as described in Bylaw 188.8.131.52 (see Guideline 2i)."
The NCAA Plan
- Requires that student-athletes receive information about the signs and symptoms of concussions. They also are required to sign a waiver that says they are responsible for reporting injuries to the medical staff.
- Mandates institutions to provide a process for removing a student-athlete that exhibits signs of a concussion. Student-athletes exhibiting signs of concussions must be evaluated by a medical staff member with experience in the evaluation and management of concussions before they can return to play.
- Prohibits a student-athlete with concussion symptoms from returning to play on the day of the activity.
- Requires student-athletes diagnosed with a concussion be cleared by a physician or a physician's designee before they are permitted to return.
The signs of a concussion, according to the NCAA, are as follows:
- Loss of consciousness
- Balance problems
- Double or fuzzy vision
- Sensitivity to light or noise
- Feeling sluggish
- Concentration or memory problems
- Slowed reaction time
- Feeling unusually irritable
The NCAA handbook includes much more information on concussions starting on page 55. The NCAA also recommends viewing the National Athletic Trainers' Association's Heads Up video, which takes a closer look at the types of head injuries incurred and how they happen.
Sports-related neurosurgical injuries were the focus of the November 2011 issue of the Journal of Neurosurgery. It included the results of a study of 451 patients about the mechanisms and consequences of head injuries referencing an anonymous survey that found that more than 46% of university soccer players experienced a concussion in just one fall season, and almost two-thirds of the same group experienced a concussion over the 12-month period while playing soccer. Another article described a new smartphone app designed for on-the-field concussion testing.
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This page has been edited by Nitin Agarwal, MD, Rut Thakkar and Khoi Than, MD, FAANS
The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific neurosurgical advice or assistance should consult his or her neurosurgeon, or locate one in your area through the AANS’ Find a Board-certified Neurosurgeon”online tool.