Concussion

Updated: Jul 26, 2017
  • Author: David T Bernhardt, MD; Chief Editor: Craig C Young, MD  more...
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Overview

Practice Essentials

Concussion, or mild traumatic brain injury (MTBI), is common among contact and collision sports participants. [1, 2, 3, 4, 5, 6, 7] One definition of concussion is a condition in which there is a traumatically induced alteration in mental status, with or without an associated loss of consciousness (LOC). [1] A broader definition is a traumatically induced physiologic disruption in brain function that is manifested by LOC, memory loss, alteration of mental state or personality, or focal neurologic deficits.

See Pediatric Concussion and Other Traumatic Brain Injuries, a Critical Images slideshow, to help identify the signs and symptoms of TBI, determine the type and severity of injury, and initiate appropriate treatment.

Also, see the Common Pediatric Sports and Recreational Injuries slideshow to help recognize some of the more common injuries and conditions associated with pediatric recreational activities.

Signs and symptoms

An athlete suffering from an MTBI may demonstrate the following:

  • Confusion: Athletes with an MTBI often appear acutely with a confused or blank expression or blunted affect
  • Delayed responses and emotional changes: Delayed response to simple questioning may be demonstrated, along with emotional lability; the emotional lability may become more evident as the athlete attempts to cope with his or her confusion
  • Pain/dizziness: Many athletes report an associated headache and dizziness
  • Visual disturbances: Visual complaints may include seeing stars, blurry vision, or double vision
  • Amnesia: Pretraumatic (retrograde) and posttraumatic (antegrade) amnesia may be present; usually, the duration of retrograde amnesia is quite brief, while the duration of posttraumatic amnesia is more variable (lasting seconds to minutes), depending upon the injury
  • Signs of increased intracranial pressure: A history of persistent vomiting may suggest a significant brain injury with associated elevated intracranial pressure; other signs of increased intracranial pressure include worsening headache, increasing disorientation, and a changing level of consciousness

Physical examination

The physical examination should include assessment of the following:

  • Appearance: The initial clinical examination should include a careful inspection of the athlete's general appearance
  • Head and neck: Palpating the head and neck is important when looking for an associated skull or cervical injury
  • Facial bones: Palpate the facial bones and the periorbital, mandibular, and maxillary areas after any head trauma
  • Jaws: Open and close the mouth to help in the evaluation of possible temporomandibular joint (TMJ) pain, malocclusion, or mandibular fracture
  • Nose: Inspect the nose for deformity and tenderness, which may indicate a possible nasal fracture
  • Presence of discharge: Persistent rhinorrhea or otorrhea (clear) indicates a possible associated skull fracture.
  • Vision: Perform a careful, detailed neurologic examination that includes evaluation of the visual fields, extraocular movements, pupillary reflexes, and level of the eyes
  • Strength and sensation: Assess upper-extremity and lower-extremity strength and sensation
  • Coordination and balance: Concussed patients often have difficulty with the finger-nose-finger test and will use slow, purposeful movements to complete the task

Postconcussive syndrome

Postconcussive syndrome consists of prolonged symptoms that are related to the initial head injury. Symptoms usually consist of the following:

  • Persistent, recurrent headaches
  • Dizziness
  • Memory impairment
  • Loss of libido
  • Ataxia
  • Sensitivity to light and noise
  • Concentration and attention problems
  • Depression
  • Anxiety

See Clinical Presentation for more detail.

Diagnosis

Imaging

The following imaging studies can be used in the examination of head injury (Note: Although the following studies may be useful in the evaluation of head trauma, they will be negative for a concussion with no other injury.):

  • Computed tomography scanning: CT scanning continues to be the imaging study of choice for evaluating acute head injury
  • Magnetic resonance imaging: MRI is the imaging study of choice for patients who have prolonged symptoms (>7 days) or when a late change occurs in an individual's neurologic signs or symptoms

Although positron emission tomography (PET) scanning and functional MRI (fMRI) may be used in evaluating patients with concussion, their clinical application in most cases of MTBI is uncertain. [8, 9, 10]

Neuropsychological testing

Detailed neuropsychologic testing is employed more often at the professional level and in research in athletes with MTBI.

See Workup for more detail.

Management

Most patients with MTBI recover in 48-72 hours, even with detailed neuropsychological testing, and are headache free within 2-4 weeks of the injury.

A clinical report by the American Academy of Pediatrics (AAP) on the diagnosis and management of sports-related concussions in adolescents and children noted the following [11] :

  • Cognitive and physical rest is the mainstay of management of patients with concussion
  • Ongoing neuropsychological testing is a helpful tool during management

Although several different guidelines regarding return to play have been established, the main criteria for an athlete's return to play after a concussion include the following:

  • Complete clearing of all symptoms
  • Complete return of all memory and concentration
  • No symptoms after provocative testing: Provocative testing includes jogging, sprinting, sit-ups, or pushups (ie, exercise that raises the athlete's blood pressure and heart rate)

Davis and Purcell have released an assessment of the evaluation and management of acute concussion in young children. [12]

In 2013, the American Academy of Neurology issued updated guidelines for the evaluation and management of sports concussion. [13]

See Treatment and Medication for more detail.

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Background

Concussion has many different meanings to patients, families, and physicians. [1, 14, 15, 16] One definition of concussion is a condition in which there is a traumatically induced alteration in mental status, with or without an associated loss of consciousness (LOC). [1] A broader definition for concussion is a traumatically induced physiologic disruption in brain function that is manifested by LOC, memory loss, alteration of mental state or personality, or focal neurologic deficits. [1] Concussions usually result in relatively temporary impairment of neurologic function. [8, 16, 17]

Concussion or mild traumatic brain injury (MTBI) is common among most contact and collision sports participants. [1, 2, 3, 4, 5, 6, 7] For many physicians, even those who specialize in MTBI, this area is confusing due to the paucity of scientific evidence to support much of the clinical decision making that is faced in the office. [4, 9, 14, 15, 18] The inconsiderable amount of good scientific research in the area of MTBI is due to problems with ambiguous definitions of concussion, inconsistent criteria when selecting patients to study, variability of injury mechanisms and locations, and differing means of measuring cognitive function. [19, 20] The purpose of this article is to review the epidemiology and diagnosis (but not necessarily the classification) of MTBI, as well as the role of imaging studies, issues regarding return to play, and complications surrounding MTBI.

For patient education information, see the Back, Ribs, Neck, and Head Center, Brain and Nervous System, and Dementia Center, as well as Concussion, Head Injury, and Dementia in Head Injury.

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Epidemiology

Frequency

United States

The incidence of head injury varies with the sport and the age of the participants; many head injuries are likely unreported due to their supposed mild nature; mild concussions may go unnoticed by teammates, coaches, and even the athletes themselves. [1] An athlete's fear of medical disqualification may also lead to underreporting. Studies of high school athletes show the rate of concussions per 1000 exposures as follows: 0.59 for football (boys), 0.25 for wrestling (boys), 0.18 for soccer (boys; 0.23 for girls), 0.09 for field hockey (girls), and 0.11 for basketball (boys; 0.16 for girls). The data from one study noted that concussions account for nearly 15% of all sport-related injuries in high school athletes. [21]

Among National Collegiate Athletic Association (NCAA) soccer players, the rate of injury has been reported as 0.4-0.6 per 1000 athlete exposures [6] ; 72% of these injuries were described as mild and were almost always secondary to direct contact with an opponent. None of the injuries in this group of Atlantic Coast Conference (ACC) soccer players was noted to be a direct result of heading the ball. In contrast, boxing is the sport with the highest rate of head injuries and has more deaths than any other organized athletic activity. At the professional level, many of the boxing bouts end with a technical knockout (ie, brain injury).

Sports activities that place the athlete at high risk for a head injury include boxing, football, ice hockey, wrestling, rugby, and soccer. Physicians and other allied health providers who are responsible for the medical care of such contact or collision sports participants should be adept at evaluating, treating, and making playability decisions related to the short- and long-term consequences of an injury to the brain.

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Sport-Specific Biomechanics

The mechanisms of brain injury may differ among sports activities. Possible mechanisms of injury include compressive forces, which may directly injure the brain at the point of contact (coup); tensile forces produce injury at the point opposite the injury (contrecoup) because the axons and nerves are stretched; finally, rotational forces may result in a shearing of axons. Therefore, the direct force at the point of contact may not be solely responsible for the severity of an injury if a high rotational component with a significant shear effect occurs.

All of the different mechanisms may result in biochemical changes related to perfusion, energy demand, and utilization at the site of injury that are not well understood. At this time, it is unclear whether any experimental animal model or human studies on more severe brain-injured patients accurately reflect the pathophysiology of the typical mild traumatic alteration in brain function.

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