Description

Concussion (aka mild traumatic brain injury [mTBI]), is defined as a complex pathophysiologic process affecting the brain, induced by traumatic biomechanical forces. This can be caused by a direct blow to the head or indirectly anywhere on the body where impulsive force is then transmitted to the head (1)[C]. Concussion may or may not involve loss of consciousness, with headache, dizziness, and confusion identified as the most common complaints. There is currently no accepted classification system for concussions.

Pediatric Considerations
Resolution of symptoms and return to neurocognitive baseline often take longer in pediatric and adolescent athletes (<18 years) (2)[C].

Epidemiology

• The CDC estimates 1.6–3.8 million concussions every year, although many go unreported (3)[C].
• >1 million ER visits every year are due to TBIs (falls, MVAs, assault, sports, other) (3)[C]:
  • >½ of these visits are by children 5–18 years
• High school and college athlete concussion rates have increased in the past 30 years (3)[C].
• American football is associated with the highest number of TBIs.
• Concussions occur more often in games than practices (3)[C].
• Female athletes have more reported concussions than male athletes and more frequently suffer cognitive impairment (3)[C].

• The most common cause of TBI in the elderly (>65) is falls.
• Sports:
  • Football: College 0.61 per 1,000 (0.39 per 1,000 in practice, 3.02 in games), high school 0.47 per 1,000 (0.21 per 1,000 in practice, 1.55 per 1,000 in games) (3)[C]
  • Basketball: College males 0.16 per 1,000; college females 0.22 per 1,000 (3)[C]
  • Hockey: Ice 3.9%, field 1.4%. college males 0.41 per 1,000, college females 0.91 per 1,
  • Lacrosse: College males 0.26 per 1,000, college females 0.25 per 1,000 (3)[C]
  • Soccer: College males 0.49 per 1,000, high school males 0.22 per 1,000, college females 0.63 per 1,000, high school females 0.36 per 1,000 (3)[C]
  • Skiing and snowboarding: 0.005 per 1,000 and 0.004 per 1,000, respectively. Snowboarders have a higher incidence of severe brain injuries than skiers (3)[C].

Risk Factors

• Patients at high risk for falls, elderly
• History of recent concussion
• Contact sports (particularly football) and activities such as bicycling, cheerleading, skiing, and snowboarding

General Prevention

• Educate athletes, coaches, parents, and officials about signs and symptoms of concussions.
• Pre-participation exams to identify risk factors in athletes
• Strength and conditioning (athletes and elderly)
• Rule enforcement in sports (e.g., penalties for spearing or head-to-head contact) and teaching athletes correct sport-specific techniques
• Protective equipment, such as helmets and mouth guards, decrease injuries but have not been shown to decrease risk of concussion.

Pathophysiology

• Structural abnormalities of the brain are typically absent based on imaging studies (4)[A].
• Identifiable metabolic changes include alterations in intra-/extracellular potassium, calcium, and glutamate with subsequent neuron dysfunction. Micro-tearing of cerebral blood vessels and a relative decrease in cerebral blood flow also occurs. An increased requirement for glucose by the brain, coupled with decreased blood flow, may result in cell dysfunction and increased susceptibility to subsequent brain insults (1)[C].

Etiology

Direct or indirect injury to the head:

• Falls
• Sports-related injury
• Motor vehicle accidents