Concussions, a type of traumatic brain injury, are a frequent concern for those playing sports, from children and teenagers to professional athletes. Repeated concussions are a known cause of various neurological disorders, most notably chronic traumatic encephalopathy (CTE), which in professional athletes has led to premature retirement, erratic behavior and even suicide. The terms mild brain injury, mild traumatic brain injury (MTBI), mild head injury (MHI), minor head trauma, and concussion may be used interchangeably.

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Signs and symptoms

Physical

Headache is the most common MTBI symptom. Others include dizziness, vomiting, nausea, lack of motor coordination, difficulty balancing, or other problems with movement or sensation. Visual symptoms include light sensitivity, seeing bright lights, blurred vision, and double vision. Tinnitus, or a ringing in the ears, is also commonly reported. In one in about seventy concussions, concussive convulsions occur, but seizures that take place during or immediately after concussion are not 'post-traumatic seizures', and, unlike post-traumatic seizures, are not predictive of post-traumatic epilepsy, which requires some form of structural brain damage, not just a momentary disruption in normal brain functioning. Concussive convulsions are thought to result from temporary loss or inhibition of motor function, and are not associated either with epilepsy or with more serious structural damage. They are not associated with any particular sequelae, and have the same high rate of favorable outcomes as concussions without convulsions.

Cognitive and emotional

Cognitive symptoms include confusion, disorientation, and difficulty focusing attention. Loss of consciousness may occur, but is not necessarily correlated with the severity of the concussion if it is brief. Post-traumatic amnesia, in which events following the injury cannot be recalled, is a hallmark of concussion. Confusion, another concussion hallmark, may be present immediately or may develop over several minutes. A person may repeat the same questions, be slow to respond to questions or directions, have a vacant stare, or have slurred or incoherent speech. Other MTBI symptoms include changes in sleeping patterns and difficulty with reasoning, concentrating, and performing everyday activities.

Concussion can result in changes in mood including crankiness, loss of interest in favorite activities or items, tearfulness, and displays of emotion that are inappropriate to the situation. Common symptoms in concussed children include restlessness, lethargy, and irritability.

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Dangers

Concussion symptoms can last for an undetermined amount of time depending on the player and the severity of the concussion. A concussion will affect the way a person's brain works.

There is the potential of post-concussion syndrome, post-concussion syndrome is defined as a set of symptoms that may continue after a concussion is sustained. Post-concussion symptoms can be classified into physical, cognitive, emotional, and sleep symptoms. Physical symptoms include a headache, nausea, and vomiting. Athletes may experience cognitive symptoms that include speaking slowly, difficulty remembering and concentrating. Emotional and sleep symptoms include irritability, sadness, drowsiness, and trouble falling asleep.

Along with the classification of post-concussion symptoms, the symptoms can also be described as immediate and delayed.

• The immediate symptoms are experienced immediately after a concussion such as: memory loss, disorientation, and poor balance.
• Delayed symptoms are experienced in the later stages and include sleeping disorders and behavioral changes. Both immediate and delayed symptoms can continue for long periods of time and have a negative impact on recovery. According to research, 20-25% of individuals who have sustained a concussion experienced chronic, delayed symptoms.

Playing through concussion makes people more vulnerable to getting hit again, and that is why most sports have test that trainers will perform to prevent getting hit a second time. A second blow can cause a rare condition known as second-impact syndrome, which can result in severe injury or death. Second-impact syndrome is when an athlete suffers a second head injury before the brain has adequate time to heal in between concussions.

Repeated concussions have been linked to a variety of neurological disorders among athletes, including CTE, Alzheimer's Disease, Parkinsonism and Amyotrophic lateral sclerosis (ALS).

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Incidence

It is estimated that as many as 1.6-3.8 million concussions occur in the US per year in competitive sports and recreational activities; this is a rough estimate, since as many as 50% of concussions go unreported. Concussions occur in all sports with the highest incidence in American football, hockey, rugby, soccer, and basketball. In addition to concussions caused by a single severe impact, multiple minor impacts may also cause brain injury.

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Policies

Major League Baseball

Major League Baseball's policy was first started in 2007, and injured players are examined by a team athletic trainer on the field. On March 29, 2011, MLB and the Major League Baseball Players Association announced that they have created various protocols for the league's concussion policy.

The new policy includes four primary components:

• All teams are to run baseline neurocognitive testing for all players and umpires using the ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing) system during spring training or after a player signing.
• The SCAT2 (Sport Concussion Assessment Tool, version 2) has been adopted as the official sideline concussion assessment tool of the league, even though various teams have already adopted this tool.
• The establishment of the 7-day disabled list for players with concussions. Players who have been on the list for 14 days are to be transferred to the 15-day list.
• Any player who has been diagnosed with a concussion, regardless of being placed on the disabled list, must have his team submit a return-to-play form to the league's medical director to in order for that player to be cleared to play.

National Basketball Association

The National Basketball Association does not have a policy, and team procedures after concussions vary by team. The NBA has a meeting to educate the players each year about concussions. Players also go through a neurological and cognitive assessment after each season.

National Football League

The National Football League's policy was first started in 2007, and injured players are examined on field by the medical team. The league's policy included the "NFL Sidelines Concussion Exam", which requires players who have taken hits to the head to perform tests concerning concentration, thinking and balance. In 2011, the league introduced an assessment test, which combines a symptoms checklist, a limited neurological examination, a cognitive evaluation, and a balance assessment. For a player to be allowed to return, he must be asymptomatic.

National Hockey League

The National Hockey League's concussion policy began in 1997, and players who sustain concussions are evaluated by a team doctor in a quiet room. In March 2011, the NHL adopted guidelines for the league's concussion policy. Before the adoptions, examinations on the bench for concussions was the minimum requirement, but the new guidelines make it mandatory for players showing concussion-like symptoms to be examined by a doctor in the locker room.

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Treatment

After exclusion of neck injury, observation should be continued for several hours. If repeated vomiting, worsening headache, dizziness, seizure activity, excessive drowsiness, double vision, slurred speech, unsteady walk, or weakness or numbness in arms or legs, or signs of basilar skull fracture develop, immediate assessment in an emergency department is warranted. After this initial period has passed, there is debate as to whether it is necessary to awaken the person several times during the first night, as has traditionally been done, or whether there is more benefit from uninterrupted sleep.

Physical and cognitive rest should be continued until all symptoms have resolved with most (80–90%) concussions resolving in seven to ten days, although the recovery time may be longer in children and adolescents. Cognitive rest includes reducing activities which require concentration and attention such as school work, video games, and text messaging. It has been suggested that even leisure reading can commonly worsen symptoms in children and adolescents and proposals include time off from school and attending partial days. Since students may appear 'normal', continuing education of relevant school personnel may be needed.

Those with concussion are generally prescribed rest, including adequate nighttime sleep as well as daytime rest. Rest includes both physical and cognitive rest until symptoms clear and a gradual return to normal activities at a pace that does not cause symptoms to worsen is recommended. Education about symptoms, their management, and their normal time course, can lead to an improved outcome.

For persons participating in athletics, the 2008 Zurich Consensus Statement on Concussion in Sport recommends that participants be symptom free before restarting and then progress through a series of graded steps. These steps include:

• complete physical and cognitive rest
• light aerobic activity (less than 70% of maximum heart rate)
• sport-specific activities such as running drills and skating drills
• non-contact training drills (exercise, coordination, and cognitive load)
• full-contact practice
• full-contact games.

Only when symptom-free for 24 hours, should progression to the next step occur. If symptoms occur, the person should drop back to the previous asymptomatic level for at least another 24 hours. The emphasis is on remaining symptom free and taking it in medium steps, not on the steps themselves.

Medications may be prescribed to treat sleep problems and depression. Analgesics such as ibuprofen can be taken for headache, but paracetamol (acetaminophen) is preferred to minimize the risk of intracranial hemorrhage. Concussed individuals are advised not to use alcohol or other drugs that have not been approved by a doctor as they can impede healing. Activation database-guided EEG biofeedback has been shown to return the memory abilities of the concussed individual to levels better than the control group.

About one percent of people who receive treatment for MTBI need surgery for a brain injury. Observation to monitor for worsening condition is an important part of treatment. Health care providers recommend that those suffering from concussion return for further medical care and evaluation 24 to 72 hours after the concussive event if the symptoms worsen. Athletes, especially intercollegiate or professional, are typically followed closely by team athletic trainers during this period but others may not have access to this level of health care and may be sent home with minimal monitoring.

People may be released after assessment from hospital or emergency room to the care of a trusted person with instructions to return if they display worsening symptoms or those that might indicate an emergent condition such as: change in consciousness, convulsions, severe headache, extremity weakness, vomiting, new bleeding or deafness in either or both ears.

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