Concussion, or mild traumatic brain injury (MTBI), is the most common and least serious type of brain injury. Concussion is a "trauma-induced alteration in mental status that may or may not involve loss of consciousness".  A loss of consciousness is infrequent although some definitions require a loss of consciousness. It can be caused by acceleration or deceleration forces, or by a direct blow. Concussion is generally not associated with penetrating injuries, but instead with blunt trauma.
- 1 Classification
- 2 Symptoms
- 3 Diagnosis
- 4 Pathophysiology
- 5 Prognosis
- 6 Treatment
- 7 References
- 8 External links
- Transient confusion
- No loss of consciousness
- Concussion symptoms or mental status abnormalities on examination resolve in less than 15 minutes.
- Transient confusion
- No loss of consciousness
- Concussion symptoms or mental status abnormalities on examination last more than 15 minutes
- Any loss of consciousness, either brief (seconds) or prolonged (minutes).
|No loss of consciousness nor amnesia||78%|
|Loss of consciousness|| 6%|
(median duration, 30 seconds)
| Anterograde amnesia
Events after the injury
such as exiting the field
(median duration, 90 minutes)
| Retrograde amnesia
Events before the injury
such as inability to recall aspects of the play
(median duration, 120 minutes)
|Delayed onset of symptoms||12%|
(mean delay; 14+15 minutes)
In a study of concussions in Australian Football League, 44% (102 of 234) were recorded during television broadcast. Among the concussions recorded on television, 25% showed tonic posturing lasting 2 to 30 seconds with "abduction and elevation of semiflexed arms and shoulders in a 'bear-hug' posture" similar to decorticate rigidity while one-quarter of the patients with posturing also had clonic movements usually less than 10 seconds. Seizures may occasionally occur.
8% of patients have acute intracranial lesions; less than 2% of concussions require neurosurgery.X-ray computed tomography of the head should be considered, especially if the patient fulfills any criteria from the New Orleans Criteria clinical prediction rule for brain injury:
- "headache, vomiting, an age over 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicles, and seizure"
- Age 65 years or more
- Paresthesias in extremities
- Dangerous fall ("elevation >=3 ft or 5 stairs; an axial load to the head (e.g., diving); a motor vehicle collision at high speed (>100 km/hr) or with rollover or ejection; a collision involving a motorized recreational vehicle; or a bicycle collision")
- Inability to rotate the neck 45° to the right and left
- Only test if "simple rear-end motor vehicle collision, sitting position in ED, ambulatory at any time since injury, delayed onset of neck pain, or absence of midline C-spine tenderness"
- Glasgow Coma Scale less than 15 (the Canadian C-Spine Rule was only designed for alert patients)
A cohort study of NCAA football players found that signs and symptoms typically last 3.5 days and resolvee by one week in 88%. In the same cohort study, slow recovery from concussion is more likely among players with a history of previous concussions and tends to be slower when unconsciousness or amnesia occurred.
Second Impact Syndrome
Cognitive impairment and dementia
Among retired NFL players, "players with three or more reported concussions had a fivefold prevalence of mild cognitive impairment diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion...we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population" This association has not been found among current athletes.
Concussion in sports
Various Clinical practice guidelines and expert opinion address management in sports medicine. Additional recommendations have been based on severity of the concussion and prior concussion (see Ropper et al Table 3.
American Academy of Pediatrics
AAP guidelines are online.
American Academy of Neurology
- "Remove from contest"
- "Examine immediately and at 5 minute intervals for the development of mental status abnormalities or post-concussive symptoms at rest and with exertion."
- "May return to contest if mental status abnormalities or post-concussive symptoms clear within 15 minutes.
- "A second Grade 1 concussion in the same contest eliminates the player from competition that day, with the player returning only if asymptomatic for one week at rest and with exercise."
- "Remove from contest and disallow return that day."
- "Examine on-site frequently for signs of evolving intracranial pathology."
- "A trained person should reexamine the athlete the following day."
- "A physician should perform a neurologic examination to clear the athlete for return to play after 1 full asymptomatic week at rest and with exertion."
- CT or MRI scanning is recommended in all instances where headache or other associated symptoms worsen or persist longer than one week."
- Following a second Grade 2 concussion, return to play should be deferred until the athlete has had at least two weeks symptom-free at rest and with exertion."
- Terminating the season for that player is mandated by any abnormality on CT or MRI scan consistent with brain swelling, contusion, or other intracranial pathology."
- "Transport the athlete from the field to the nearest emergency department by ambulance if still unconscious or if worrisome signs are detected (with cervical spine immobilization, if indicated)."
- "A thorough neurologic evaluation should be performed emergently, including appropriate neuroimaging procedures when indicated."
- "Hospital admission is indicated if any signs of pathology are detected, or if the mental status of the athlete remains abnormal."
- "If findings are normal at the time of the initial medical evaluation, the athlete may be sent home. Explicit written instructions will help the family or responsible party observe the athlete over a period of time."
- "Neurologic status should be assessed daily thereafter until all symptoms have stabilized or resolved."
- "Prolonged unconsciousness, persistent mental status alterations, worsening postconcussion symptoms, or abnormalities on neurologic examination require urgent neurosurgical evaluation or transfer to a trauma center."
- "After a brief (seconds) Grade 3 concussion, the athlete should be withheld from play until asymptomatic for 1 week at rest and with exertion."
- "After a prolonged (minutes) Grade 3 concussion, the athlete should be withheld from play for 2 weeks at rest and with exertion."
- "Following a second Grade 3 concussion, the athlete should be withheld from play for a minimum of 1 asymptomatic month. The evaluating physician may elect to extend that period beyond 1 month, depending on clinical evaluation and other circumstances."
- "CT or MRI scanning is recommended for athletes whose headache or other associated symptoms worsen or persist longer than 1 week."
- "Any abnormality on CT or MRI consistent with brain swelling, contusion, or other intracranial pathology should result in termination of the season for that athlete and return to play in the future should be seriously discouraged in discussions with the athlete."
2nd International Conference on Concussion in Sport
The 2nd International Conference on Concussion in Sport recommends:
For the acute injury:
- The player should not be allowed to return to play in the current game or practice.
- The player should not be left alone, and regular monitoring for deterioration is essential over the initial few hours after injury.
- The player should be medically evaluated after the injury.
- Return to play must follow a medically supervised stepwise process.
- A player should never return to play while symptomatic.
Return to play protocol:
- No activity, complete rest. Once asymptomatic, proceed to level 2.
- Light aerobic exercise such as walking or stationary cycling, no resistance training.
- Sport specific exercise—for example, skating in hockey, running in soccer; progressive addition of resistance training at steps 3 or 4.
- Non-contact training drills.
- Full contact training after medical clearance.
- Game play.
- Meehan WP, Bachur RG (January 2009). "Sport-related concussion". Pediatrics 123 (1): 114–23. DOI:10.1542/peds.2008-0309. PMID 19117869. Research Blogging.
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- McCrea M, Guskiewicz KM, Marshall SW, et al (November 2003). "Acute effects and recovery time following concussion in collegiate football players: the NCAA Concussion Study". JAMA 290 (19): 2556–63. DOI:10.1001/jama.290.19.2556. PMID 14625332. Research Blogging.
- Guskiewicz KM, McCrea M, Marshall SW, et al (November 2003). "Cumulative effects associated with recurrent concussion in collegiate football players: the NCAA Concussion Study". JAMA 290 (19): 2549–55. DOI:10.1001/jama.290.19.2549. PMID 14625331. Research Blogging.
- McCrory PR, Berkovic SF (April 2000). "Video analysis of acute motor and convulsive manifestations in sport-related concussion". Neurology 54 (7): 1488–91. PMID 10751264.
- McCrory PR, Berkovic SF (February 1998). "Concussive convulsions. Incidence in sport and treatment recommendations". Sports Med 25 (2): 131–6. PMID 9519401.
- Ibañez J, Arikan F, Pedraza S, et al (May 2004). "Reliability of clinical guidelines in the detection of patients at risk following mild head injury: results of a prospective study". J. Neurosurg. 100 (5): 825–34. PMID 15137601.
- Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PM (July 2000). "Indications for computed tomography in patients with minor head injury". N. Engl. J. Med. 343 (2): 100–5. PMID 10891517.
- Stiell IG, Clement CM, McKnight RD, et al (December 2003). "The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma". N. Engl. J. Med. 349 (26): 2510–8. DOI:10.1056/NEJMoa031375. PMID 14695411. Research Blogging.
- Stiell IG, Wells GA, Vandemheen KL, et al (October 2001). "The Canadian C-spine rule for radiography in alert and stable trauma patients". JAMA 286 (15): 1841–8. PMID 11597285.
- Lovell MR, Pardini JE, Welling J, et al (August 2007). "Functional brain abnormalities are related to clinical recovery and time to return-to-play in athletes". Neurosurgery 61 (2): 352–9; discussion 359–60. DOI:10.1227/01.NEU.0000279985.94168.7F. PMID 17762748. Research Blogging.
- McCrory P (July 2001). "Does second impact syndrome exist?". Clin J Sport Med 11 (3): 144–9. PMID 11495318.
- McCrory PR, Berkovic SF (March 1998). "Second impact syndrome". Neurology 50 (3): 677–83. PMID 9521255.
- Guskiewicz KM, Marshall SW, Bailes J, et al (October 2005). "Association between recurrent concussion and late-life cognitive impairment in retired professional football players". Neurosurgery 57 (4): 719–26; discussion 719–26. PMID 16239884.
- Collie A, McCrory P, Makdissi M (June 2006). "Does history of concussion affect current cognitive status?". Br J Sports Med 40 (6): 550–1. DOI:10.1136/bjsm.2005.019802. PMID 16720889. Research Blogging.
- Zafonte, Ross (2011-07-06). "Diagnosis and Management of Sports-Related Concussion". JAMA: The Journal of the American Medical Association 306 (1): 79 -86. DOI:10.1001/jama.2011.819. Retrieved on 2011-07-07. Research Blogging.
- Halstead ME, Walter KD, Council on Sports Medicine and Fitness (2010). "American Academy of Pediatrics. Clinical report--sport-related concussion in children and adolescents.". Pediatrics 126 (3): 597-615. DOI:10.1542/peds.2010-2005. PMID 20805152. Research Blogging.
- McCrory P, Johnston K, Meeuwisse W, et al (April 2005). "Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004". Br J Sports Med 39 (4): 196–204. DOI:10.1136/bjsm.2005.018614. PMID 15793085. PMC 1725173. Research Blogging. Pubmed Central
- Sport Concussion Assessment Tool (SCAT card). Complete version is available at http://bjsm.bmj.com/cgi/content/full/39/4/196/F1.