Concussion

Concussion Overview

• Prevalence and Incidence

  According to the University of Pittsburgh's Brain Trauma Research Center, more than 300,000 sports-related concussions occur annually in the United States, and the likelihood of suffering a concussion while playing a contact sport is estimated to be as high as 19 percent per year of play. More than 62,000 concussions are sustained each year in high school contact sports, and among college football players, 34 percent have had one concussion and 20 percent have endured multiple concussions. Concussions often cause significant and sustained neuropsychological impairments in information-processing speed, problem solving, planning, and memory, and these impairments are worse with multiple concussions.

  Reasonable estimates show that between four and 20 percent of college and high school football players will 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 percent of college soccer players reported symptoms of a concussion at least once during the season. The study also revealed 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.

  Concussions also are commonly caused by automobile and biking accidents, and by falls around the home, especially among toddlers and older adults.

• Grading Concussions

  There is no universal agreement on the grades of severity for a concussion. There are many different guidelines for concussion evaluation and return-to-play decisions in athletes. Most guidelines recognize three different grades of concussions and share similar recommendations for return to play.

  The two sets of guidelines most followed in the U.S. were formulated by the American Academy of Neurology (AAN) and Robert C. Cantu, MD.

  Grading the concussion is a helpful tool in the management of the injury (see Cantu, below) and depends on: 1) presence or absence of loss of consciousness, 2) duration of loss of consciousness, 3) duration of posttraumatic memory loss, and 4) persistence of symptoms, including headache, dizziness, lack of concentration, etc.

  Some team physicians and trainers evaluate an athlete's mental status by using a five-minute series of questions and physical exercises known as the Standardized Assessment of Concussion (SAC). This method, however, may not be comprehensive enough to pick up subtle changes.

  The Centers for Disease Control (CDC) offers a Concussion Tool Kit. It also offers a Heads Up Concussion in Youth Sports online training course for coaches.

  According to the Cantu Guidelines, Grade I concussions are not associated with loss of consciousness, and post-traumatic amnesia is either absent or less than 30 minutes in duration. Athletes may return to play if no symptoms are present for one week.

  Players who sustain a Grade II concussion lose consciousness for less than five minutes or exhibit posttraumatic amnesia between 30 minutes and 24 hours in duration. They also may return to play after one week of being asymptomatic.

  Grade III concussions involve post-traumatic amnesia for more than 24 hours or unconsciousness for more than five minutes. Players who sustain this grade of brain injury should be sidelined for at least one month, after which they can return to play if they are asymptomatic for one week.

  Following repeated concussions, a player should be sidelined for longer periods of time and possibly not allowed to play for the remainder of the season.

• Concussions and Head Injuries

  The brain normally floats inside the skull, cushioned gently by the surrounding spinal fluid. The brain consists of a gelatin-like substance and is vulnerable to outside trauma. The skull protects the brain against trauma, but does not absorb all the impact of a violent force.

  An abrupt blow to the head, or even a rapid deceleration, can cause the brain to bounce against the inner wall of the skull. There is a potential for tearing of blood vessels, pulling of nerve fibers and bruising of the brain substance.

  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, and limit 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 involving bleeding and swelling in the brain. It can be thought of as a bruise of the brain tissue.

  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 even be life-threatening. Some hematomas are surgical emergencies. Hematomas that are small sometimes can go undetected initially, but may cause symptoms and require treatment several days or weeks later. The warning signs of a serious brain injury are:

  • Pain: Constant or recurring headache
  • Motor dysfunction: Inability to control or coordinate motor functions, or disturbance with 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.

• Symptoms

  Like concussions, mild injuries to the brain may not be observable in routine neurological examinations. Diagnostic tests typically will not show any changes. Therefore, diagnosis is based on the nature of the incident and the presence of specific symptoms, confusion being a primary one. The three principal features of confusion are:

  • Inability to maintain a coherent stream of thought
  • A disturbance of awareness with heightened distractibility

  Inability to carry out a sequence of goal-directed movements

  The following are concussion symptoms:

  • Prolonged headache
  • Vision disturbances
  • Dizziness
  • Nausea or vomiting
  • Impaired balance
  • Confusion
  • Memory loss
  • Ringing ears
  • Difficulty concentrating
  • Sensitivity to light
  • Loss of smell or taste

  If any of these occur after a blow to the head, a health-care professional should be consulted as soon as possible.

• Treatment

  The standard treatment for concussion is rest. For headaches, acetaminophen (Tylenol) can be taken. Postconcussive headaches often are resistant to stronger narcotic-based medications.

• Postconcussive Syndrome

  People who suffer a head injury may suffer from side effects that persist for weeks or months. This is known as postconcussive syndrome. Symptoms include memory and concentration problems, mood swings, personality changes, headache, fatigue, dizziness, insomnia and excessive drowsiness. Patients with postconcussive 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

  Second-impact syndrome results from acute, often fatal brain swelling that occurs when a second concussion is sustained before complete recovery from a previous concussion. This 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 such as boxing, football, ice or roller hockey, soccer, baseball, basketball and snow skiing.