General Principles
- •
Head injuries in sports are comparatively mild compared with those in high-velocity motor vehicle accidents (MVAs), yet they remain significant and important injuries for team physicians to evaluate and manage.
- •
Concussion is the most common head injury in sports. Information is evolving regarding pathophysiology, diagnosis, natural history, and treatment of concussion in sports.
- •
Consider focal, vascular, and associated injuries (e.g., cervical spine, skull fractures, intracranial hemorrhage) when evaluating head-injured athletes.
- •
Cumulative injury, postconcussive syndrome, and other sequelae of head injury may contribute to significant morbidity.
Epidemiology
- •
Many head injuries go undetected, especially in younger age groups.
- •
Athletes often underreport symptoms, contributing to the underreporting of injuries.
- •
Athletes may take injuries lightly, viewing them as “part of the game.”
- •
Athletes may fear being removed from the game if they admit symptoms.
- •
Head injuries may be evaluated on the sideline but subsequently not referred for further evaluation, or the athlete may fail to follow-up with the appropriate referral.
- •
- •
According to the National Electronic Injury Surveillance System—All Injury Program from 2001 to 2009 a total of 2.6 million emergency department visits were due to head injury. Of these, 173,285 visits were by patients under 19 years of age who sustained injuries as a result of sports and recreational activities. Head injuries represent 6% of all sports and recreational injuries.
- •
Of the 173,285 injuries, 10.6% were due to ATV accidents, 7.7% from soccer, and 7.2% from American football.
- •
Comparatively, MVAs account for 14% of head injuries, falls for 41%, and assaults for 11% (CDC data 2006–1010).
- •
- •
According to the Annual Survey of Catastrophic Football Injuries (1997–2012) in 2012, there were three cervical cord injuries and five brain injuries.
- •
The 4th International Conference on Concussion in Sport characterized concussion as a “subset of traumatic brain injury.”
- •
Concussion is the most common head injury occurring in sports, accounting for 8.9% and 5.8% of injuries at the high school and college level, respectively.
- •
Data from the National Collegiate Athletic Association (NCAA) collected from 1998–1999 to 2003–2004 demonstrated that the incidence of concussion was 5.3/1,000 athlete exposures (AEs) in women’s soccer compared to 3.9/1,000 in men’s soccer, and 4.7/1,000 AEs in women’s basketball compared to 3.2/1000 in men’s basketball. Interestingly, these two sports have similar rules across genders ( Table 45.1 ).
TABLE 45.1
NCAA INJURY SURVEILLANCE SYSTEM DATA FOR 1988-1989 THROUGH 2003-2004
Head Protection Required
% of All Game Injuries
No Head Protection
% of All Game Injuries
Men’s ice hockey *
7.9
Women’s lacrosse *
6.3
Women’s ice hockey
18.3
Wrestling
3.3
Men’s lacrosse *
5.6
Women’s soccer
5.3
Football *
6.0
Men’s soccer
3.9
Spring football * (practice)
5.6
Field hockey
3.9
Softball
4.3
Women’s basketball
4.7
Baseball
2.5
Men’s basketball
3.2
Concussion injuries in games and practices per 1,000 athlete exposures
Head protection required
No head protection
Football *
0.37
Wrestling
0.25
Men’s ice hockey *
0.41
Men’s soccer
0.28
Women’s ice hockey
0.91
Women’s soccer
0.41
Men’s lacrosse *
0.26
Women’s lacrosse *
0.25
Spring football *
0.54
Field hockey
0.18
Softball
0.14
Women’s basketball
0.22
Baseball
0.07
Men’s basketball
0.16
Data from Hootman J, Agel J, Dick R. Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train . 2007;42(2):311-319.
- •
Injury rates are comparable in sports with and without head protection.
- •
The highest overall incidence of concussion occurs in wrestling, followed by men’s football, men’s hockey, women’s field hockey, women’s soccer, women’s lacrosse, men’s lacrosse, men’s soccer, women’s basketball, men’s basketball, softball, women’s volleyball, and finally, baseball.
- •
- •
In sports with similar rules (soccer, basketball, baseball/softball), the mechanism of injury between sexes is different, with player contact to surface or equipment being more common in females than in males.
- •
Data suggest that women endorse more symptoms at baseline; however, evidence is inconclusive that there are balance/postural differences between men and women at baseline or post concussion.
- •
Exact reasons for gender differences are unclear, but they may include reporting bias, treatment bias, the effect of fluctuating sex hormone levels across the menstrual cycle, and biomechanics differences.
- •
Look at epidemiology when considering injury prevention. Before making rule or equipment changes, consider incidence of injury and how changes may affect the sport.
- •
The use of a helmet in women’s lacrosse and field hockey may decrease the incidence of facial lacerations, nasal fractures, or dental injuries but may not significantly affect the incidence of concussions. Increased aggressiveness on the part of players owing to added head protection may negatively affect the sport.
- •
One study on ice hockey reported that 75% of 246 head injuries involve violence unrelated to on-ice activities (high sticking, deliberate pushing, or fistfights).
- •
The proper enforcement of existing rules (avoiding head-to-head hits) is essential.
- •
Use of helmets significantly decreases the risk of head injury in bicycling, baseball, skiing, snowboarding, and softball, without negatively affecting the sport.
- •
There is no evidence that current helmets or mouth guards can prevent concussion. Helmets can decrease the incidence of skull fractures because of their protective plastic shell, and mouth guards can decrease incidence of tooth injury.
- •
Types of Head Injury
Head injuries occur across a large spectrum. Classifications such as diffuse versus focal or nonstructural versus structural are not absolute, but they permit the organized discussion of specific pathologies.
Diffuse Brain Injury
Diffuse Axonal Injury (DAI)
- •
Involves diffuse axonal disruption in the white matter of the brain and brainstem
- •
Severity of injury determined by clinical course
- •
Mild DAI: comatose for 6 to 24 hours; mortality rate is approximately 15%
- •
Moderate DAI: comatose for more than 24 hours; often associated with basilar fracture; mortality rate is approximately 25%
- •
Severe DAI: prolonged coma, severe disability, or persistent vegetative state common if patient survives; high mortality rate; death often caused by infectious complications, associated intracranial pathology, and other complications of prolonged coma
- •
- •
Caused by shear or tensile forces; often results from falls or motor vehicle accidents
- •
Presentation: All patients present in coma, may exhibit decorticate or decerebrate posturing, severe posttraumatic amnesia, and cognitive deficits after awakening (moderate DAI); severe DAI often includes hypertension and hyperpyrexia (autonomic dysfunction), increased intracranial pressure (ICP), posturing, and herniation syndromes.
- •
Treatment: Supportive during coma; medical or surgical measures as needed for increased ICP and associated injuries
Cerebral Concussion
- •
The Fourth International Conference on Concussion in Sport defined concussion as a “subset of traumatic brain injury” and is a “complex pathophysiologic process affecting the brain, induced by traumatic biochemical forces.”
- •
Several common features that incorporate clinical, pathologic, and biomechanical injury constructs that may be used in defining the nature of a concussive head injury include:
- •
May be caused by direct impact to head, or elsewhere on body with “impulsive” force transmitted to head
- •
Results in the rapid onset of short-lived impairment of neurologic function that usually resolves spontaneously.
- •
May result in neuropathologic changes, but acute clinical symptoms reflect functional rather than structural disturbance
- •
Results in a graded set of clinical syndromes that may or may not involve loss of consciousness. The resolution of symptoms typically follows a sequential course.
- •
Typically associated with grossly normal structural neuroimaging studies
- •
Advanced neuroimaging (e.g., diffuse tensor imagine, functional magnetic resonance imaging, magnetic resonance spectroscopy) may demonstrate abnormalities, although it currently remains primarily a research tool.
- •
- •
- •
Cerebral concussion is the most common head injury in athletes; isolated concussion has a low mortality rate.
- •
Caused by acceleration/deceleration (tensile), rotational (shearing), and impact (compressive) forces. Coup injuries often result from direct impact, whereas contrecoup injuries occur from accelerational/decelerational forces (e.g., athlete falls and strikes ground with head).
- •
Presentation: The hallmark of concussion is confusion; other signs and symptoms may occur immediately or several minutes later ( Table 45.2 ).
TABLE 45.2
SIGNS AND SYMPTOMS OF CONCUSSION
Early (Minutes to Hours)
Late (Days to Weeks)
Cognitive
Confusion
Vacant stare
Slow to answer questions or follow instructions
Easily distracted
Inability to focus
Feeling “in a fog”
Disoriented: unaware of time/date/place
Slurred or incoherent speech
Memory deficits
Repeatedly asks same question (e.g., what happened?)
Retrograde amnesia (RGA): Cannot remember events before injury
Posttraumatic amnesia (PTA): Cannot remember events after injury
Loss of consciousness
Somatic
Gross uncoordination: cannot walk straight line
Headache
Dizziness, disequilibrium or vertigo
Visual disturbances (blurry vision, photophobia)
Phonophobia
Fatigue
Nausea and/or vomiting
Seizure
Affective
Emotional lability: may cry for no apparent reason
Irritability
Nausea and/or vomiting
Seizure
Persistent low-grade headache
Lightheadedness
Poor attention and concentration
Memory dysfunction
Anomia (cannot think of word one wants to say)
Easy fatigability
Irritability and frustration
Difficulty with focusing vision
Photophobia
Phonophobia
Anxiety and/or depression
Sleep disturbance
Persistent cognitive deficits
Postconcussive syndrome
- •
Treatment: Rest (physical and cognitive), protection from further injury, and serial follow-up evaluations (see detailed discussion below)
Pathophysiology of Concussion
- •
Concussion is associated with neurochemical and metabolic changes with changes in glutamate, potassium, lactate, and glucose, as well as changes in cerebral blood flow.
- •
No current objective neuroanatomic or neurophysiologic measurements can be used practically and reliably to determine if an athlete has a concussion. See the Diagnostic Testing section.
- •
After concussion, the brain cells may be in state of injury-induced vulnerability; a second injury during this time of heightened vulnerability may produce additional deficits.
- •
Injury-induced vulnerability is characterized by a fuel need–fuel delivery mismatch. The brain’s need for glucose increases acutely (hyperglycolysis), and cerebral blood flow and oxidative metabolism are relatively reduced (sometimes called the disruption of metabolic autoregulation).
- •
Increased levels of extracellular potassium probably activate adenosine triphosphate (ATP)-dependent sodium–potassium pumps, which increases energy consumption and adds to metabolic stress (e.g., need for glucose).
- •
Glutamate (excitatory amino acid) levels increases extracellularly and may contribute to an increased flux of potassium.
- •
Increased intracellular calcium may be related to regional reduction of cerebral blood flow.
- •
Not known whether normalization of injury-induced neurometabolical and neurochemical abnormalities correlates with resolution of concussive signs and symptoms, but timeline of changes correlates with changes in neuropsychologic function
- •
Focal Brain Injury
Subdural Hematoma
- •
Low-pressure venous bleed into potential space (subdural) between the arachnoid and dura mater; classified by time to clinical presentation (see Fig. 45.1 ).
- •
Acute: within 24 hours; often associated with other intracranial pathology (e.g., contusion, axonal injury)
- •
Subacute: 24 hours to 2 weeks
- •
Chronic: 2 weeks or more
- •
