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| {{Concussion}} | | {{Concussion}} |
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| ==Definitions== | | ==[[Concussion overview|Overview]]== |
| No single definition of concussion, mild head injury,<ref name="SatzZaucha">
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| {{
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| cite journal |author=Satz P, Zaucha K, McCleary C, Light R, Asarnow R, Becker D |title=Mild head injury in children and adolescents: A review of studies (1970–1995) |journal=Psychological Bulletin |volume=122 |issue=2 |pages=107–131 |year=1997 |pmid=9283296 |doi=
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| }}</ref> or mild traumatic brain injury is universally accepted, though a variety of definitions have been offered.<ref name="ComperBisschop">
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| {{
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| cite journal |author=Comper P, Bisschop SM, Carnide N, Tricco A |title=A systematic review of treatments for mild traumatic brain injury |journal=Brain Injury |volume=19 |issue=11 |pages=863–880 |year=2005 |pmid=16296570 |doi=10.1080-0269050400025042 |issn=0269-9052
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| </ref> In 2001, the first International Symposium on Concussion in Sport was organized by the International Olympic Committee Medical Commission and other sports federations.<ref name="aubry"/> A group of experts called the Concussion in Sport Group met there and defined concussion as "a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces."<ref name="canturc06">
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| cite journal |author=Cantu RC |date=2006 |url=http://www.aans.org/education/journal/neurosurgical/Oct06/21-4-3-1067.pdf |format=PDF |title=An overview of concussion consensus statements since 2000 |journal=Neurosurgical Focus |volume=21 |issue=4:E3 |pages=1–6
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| }}<!-- No PMID found -->
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| </ref> They agreed that concussion typically involves temporary impairment of neurological function which quickly resolves by itself, and that [[neuroimaging]] normally shows no gross structural changes to the brain as the result of the condition.<ref name="AndersonT"/>
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| According to the classic definition, no structural brain damage occurs in concussion;<ref>
| | ==[[Concussion historical perspective|Historical Perspective]]== |
| {{
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| cite journal |author=Parkinson D |year=1999 |title=Concussion confusion |journal=Critical Reviews in Neurosurgery |volume=9 |issue=6 |pages=335–339 |issn=1433-0377 |doi=10.1007/s003290050153
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| }}<!--Not indexed on Pubmed--></ref> it is a functional state, meaning that symptoms are caused primarily by temporary [[biochemistry|biochemical]] changes in [[neuron]]s, taking place for example at their [[cell membrane]]s and [[synapse]]s.<ref name="AndersonT"/> However, in recent years researchers have included [[injury|injuries]] in which structural damage does occur under the rubric of concussion. According to the [[National Institute for Health and Clinical Excellence]] definition, concussion may involve a physiological or physical disruption in the brain's [[chemical synapse|synapse]]s.<ref name="NICE">
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| cite web|url=http://www.nice.org.uk/nicemedia/pdf/CG56guidance.pdf|format=PDF |publisher=National Institute for Health and Clinical Excellence |title=Head Injury: Triage, Assessment, Investigation and Early Management of Head Injury in Infants, Children and Adults |isbn=0-9549760-5-3 |date=September 2007 |accessdate=2008-01-26
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| Definitions of mild traumatic brain injury (MTBI) have been inconsistent since the 1970s, but the [[World Health Organization]]'s [[ICD-10|International Statistical Classification of Diseases and Related Health Problems]] (ICD-10) described MTBI-related conditions in 1992, providing a consistent, authoritative definition across specialties.<ref name="Petchprapai07"/> In 1993, the American Congress of Rehabilitation Medicine defined MTBI as 30 minutes or fewer of [[loss of consciousness]] (LOC), 24 hours or fewer of [[post-traumatic amnesia]] (PTA), and a [[Glasgow Coma Scale]] (GCS) score of at least 13.<ref name="Kushner98">
| | ==[[Concussion classification|Classification]]== |
| {{
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| cite journal |author=Kushner D |title=Mild Traumatic brain injury: Toward understanding manifestations and treatment |journal=Archives of Internal Medicine |volume=158 |issue=15 |pages=1617–1624 |year=1998 |pmid=9701095 |doi= |url=http://archinte.highwire.org/cgi/content/full/158/15/1617
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| }}</ref> In 1994, the [[American Psychiatric Association]]'s ''[[Diagnostic and Statistical Manual of Mental Disorders]]'' defined MTBI using PTA and LOC.<ref name="Petchprapai07"/> Other definitions of MTBI incorporate focal neurological deficit and altered mental status, in addition to PTA and GCS.<ref name="ComperBisschop"/>
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| | ==[[Concussion pathophysiology|Pathophysiology]]== |
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| | ==[[Concussion causes|Causes]]== |
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| Although the term "concussion" is still used in sports literature as interchangeable with "MHI" or "MTBI", the general clinical medical literature now uses "MTBI" instead.<ref name="BarthVarney99">
| | ==[[Concussion differential diagnosis|Differentiating Concussion from other Diseases]]== |
| {{
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| cite book |author=Barth JT, Varney NR, Ruchinskas RA, Francis JP |chapter=Mild head injury: The new frontier in sports medicine |editor=Varney NR, Roberts RJ |title=The Evaluation and Treatment of Mild Traumatic Brain Injury |publisher=Lawrence Erlbaum Associates |location=Hillsdale, New Jersey |year=1999 |pages=85-86 |isbn=0-8058-2394-8 |oclc= |doi= |accessdate=2008-03-06 |url= http://books.google.com/books?id=i4Tpx6wHvJ4C&pg=PA21&vq=concussion&source=gbs_search_s&sig=t8NaFBJM5afqp0fXKb3Ou8yBjMo#PPA357,M1
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| }}</ref>
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| Controversy exists about whether the definition of concussion should include only those injuries in which [[unconsciousness|loss of consciousness]] occurs.<ref name="Pearce"/> Historically, concussion by definition involved a loss of consciousness, but the definition has changed over time to include a change in consciousness, such as amnesia.<ref name="RuffGrant">
| | ==[[Concussion epidemiology and demographics|Epidemiology and Demographics]]== |
| {{
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| cite book |author=Ruff RM, Grant I |chapter=Postconcussional disorder: Background to DSM-IV and future considerations |editor=Varney NR, Roberts RJ |title=The Evaluation and Treatment of Mild Traumatic Brain Injury |publisher=Lawrence Erlbaum Associates |location=Hillsdale, New Jersey |year=1999 |pages=320 |isbn=0-8058-2394-8 |oclc= |doi= |url=http://books.google.com/books?id=i4Tpx6wHvJ4C&pg=PA21&vq=concussion&source=gbs_search_s&sig=t8NaFBJM5afqp0fXKb3Ou8yBjMo#PPA357,M1
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| }}</ref> The best-known concussion grading scales count head injuries in which loss of consciousness does not occur to be mild concussions and those in which it does to be more severe.<ref name=cobb/>
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| ==Diagnosis== | | ==[[Concussion risk factors|Risk Factors]]== |
| Diagnosis of MTBI is based on physical and neurological exams, duration of unconsciousness (usually less than 30 minutes) and post-traumatic amnesia (PTA; usually less than 24 hours), and the Glasgow Coma Scale (MTBI sufferers have scores of 13 to 15).<ref name="BorgHolm04"/> [[Neuropsychological test]]s exist to measure cognitive function.<ref name="Rees03"/> The tests may be administered hours, days, or weeks after the injury, or at different times to determine whether there is a trend in the patient's condition.<ref name=moser>
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| {{
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| cite journal|author=Moser RS, Iverson GL, Echemendia RJ, Lovell MR, Schatz P, Webbe FM ''et al.'' |date=2007 |title=Neuropsychological evaluation in the diagnosis and management of sports-related concussion |journal=Archives of Clinical Neuropsychology |volume=22 |issue=8 |pages=909–916 |pmid=17988831
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| </ref> Athletes may be tested before a sports season begins to provide a baseline comparison in the event of an injury.<ref name="pmid10981754">
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| {{
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| cite journal |author=Maroon JC, Lovell MR, Norwig J, Podell K, Powell JW, Hartl R |title=Cerebral concussion in athletes: Evaluation and neuropsychological testing |journal=Neurosurgery |volume=47 |issue=3 |pages=659–669; discussion 669–672 |year=2000 |pmid=10981754 |doi= |url=
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| </ref>
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| [[Image:Anizokoria.JPG|left|thumb|230px|Unequal pupil size is a sign of a brain injury more serious than concussion.]]
| | ==[[Concussion natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| Health care providers examine head trauma survivors to ensure that the injury is not a more severe [[medical emergency]] such as an intracranial hemorrhage. Indications that screening for more serious injury is needed include worsening of symptoms such as headache, persistent vomiting,<ref name="CookSchweer">
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| {{
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| cite journal |author=Cook RS, Schweer L, Shebesta KF, Hartjes K, Falcone RA |title=Mild traumatic brain injury in children: Just another bump on the head? |journal=Journal of Trauma Nursing |volume=13 |issue=2 |pages=58–65 |year=2006 |pmid=16884134 |doi=
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| </ref> increasing disorientation or a deteriorating level of consciousness,<ref name="Kayteasdale">
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| {{
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| cite journal |author=Kay A, Teasdale G |title=Head injury in the United Kingdom |journal=World Journal of Surgery |volume=25 |issue=9 |pages=1210–1220 |year=2001 |pmid=11571960 |doi=10.1007/s00268-001-0084-6 |url=
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| </ref> [[post-traumatic seizure|seizure]]s, and [[anisocoria|unequal pupil size]].<ref name="cdcfacts">
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| {{
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| cite web|publisher=Centers for Disease Control and Prevention |date=2006 |url=http://www.cdc.gov/ncipc/tbi/contents.htm |title=Facts About Concussion and Brain Injury |accessdate=2008-01-13
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| </ref> Patients with such symptoms, or who are at higher risk for a more serious brain injury, are given [[Magnetic resonance imaging|MRI]]s or [[CT scan]]s to detect brain lesions and are observed by medical staff.
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| Health care providers make the decision about whether to give a CT scan using the Glasgow Coma Scale.<ref name="pmid17215534">
| | ==Diagnosis== |
| {{
| | [[Concussion diagnostic criteria|Diagnostic Criteria]] | [[Concussion history and symptoms|History and Symptoms]] | [[Concussion physical examination|Physical Examination]] | [[Concussion CT|CT]] | [[Concussion MRI|MRI]] | [[Concussion other imaging findings|Other Imaging Findings]] | [[Concussion other diagnostic studies|Other Diagnostic Studies]] |
| cite journal |author=Ropper AH, Gorson KC |title=Clinical practice. Concussion |journal=New England Journal of Medicine |volume=356 |issue=2 |pages=166–172 |year=2007|url=http://content.nejm.org/cgi/content/full/356/2/166 |pmid=17215534 |doi=10.1056/NEJMcp064645 |pmid=17215534
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| </ref> In addition, they may be more likely to perform a CT scan on people who would be difficult to observe after discharge or those who are [[intoxication|intoxicated]], at risk for bleeding, older than 60,<ref name="pmid17215534"/> or younger than 16. Most concussions cannot be detected with MRI or CT scans.<ref name="Poirier">
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| {{
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| cite journal |author=Poirier MP |year=2003 |url= |title=Concussions: Assessment, management, and recommendations for return to activity ([http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B75BD-49H1C2F-7&_user=3356446&_origUdi=B6VDJ-44KHFBN-8&_fmt=high&_coverDate=09%2F30%2F2003&_rdoc=1&_orig=article&_acct=C000060332&_version=1&_urlVersion=0&_userid=3356446&md5=9c2a61c0c62684c26cf317a8ea637458 abstract]) |journal=Clinical Pediatric Emergency Medicine |volume=4 |issue=3 |pages=179–185 |doi=10.1016/S1522-8401(03)00061-2
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| <!--abstract linked with url because doi doesn't take you right to it. no PMID found--></ref> However, changes have been reported to show up on MRI and SPECT imaging in concussed people with normal CT scans, and [[post-concussion syndrome]] may be associated with abnormalities visible on [[single photon emission computed tomography|SPECT]] and [[Positron emission tomography|PET scan]]s.<ref name="Iverson2005"/> Mild head injury may or may not produce abnormal [[Electroencephalography|EEG]] readings.<ref name="Binder86">
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| {{
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| cite journal |author=Binder LM |title=Persisting symptoms after mild head injury: A review of the postconcussive syndrome |journal=Journal of Clinical and Experimental Neuropsychology|volume=8 |issue=4 |pages=323–346 |year=1986 |pmid=3091631 |doi=10.1080/01688638608401325
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| </ref>
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| Concussion may be under-diagnosed. The lack of the highly noticeable signs and symptoms that are frequently present in other forms of head injury could lead [[clinician]]s to miss the injury, and athletes may cover up their injuries in order to be allowed to remain in the competition.<ref name="BarthVarney99"/> A retrospective survey in 2005 found that more than 88% of concussions go unrecognized.<ref name="Delaney"> | |
| {{
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| cite journal |author=Delaney JS, Abuzeyad F, Correa JA, Foxford R |title=Recognition and characteristics of concussions in the emergency department population |journal=Journal of Emergency Medicine |volume=29 |issue=2 |pages=189–197 |year=2005 |pmid=16029831 |doi=10.1016/j.jemermed.2005.01.020
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| </ref>
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| Diagnosis of concussion can be complicated because it shares symptoms with other conditions. For example, post-concussion symptoms such as cognitive problems may be misattributed to brain injury when they are in fact due to [[post-traumatic stress disorder]] (PTSD).<ref name="Bryant08"/>
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| ==Dementia pugilistica== | | ==Treatment== |
| | [[Concussion medical therapy|Medical Therapy]] | [[Concussion primary prevention|Primary Prevention]] | [[Concussion secondary prevention|Secondary Prevention]] | [[Concussion cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Concussion future or investigational therapies|Future or Investigational Therapies]] |
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| {{main|Dementia pugilistica}}
| | ==Case Studies== |
| Chronic [[encephalopathy]] is an example of the cumulative damage that can occur as the result of multiple concussions or less severe blows to the head. The condition called [[dementia pugilistica]], or "punch drunk" syndrome, which is associated with boxers, can result in cognitive and physical deficits such as [[parkinsonism]], speech and memory problems, slowed mental processing, tremor, and inappropriate behavior.<ref name="Mendez">
| | [[Concussion case study one|Case #1]] |
| {{
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| cite journal |author=Mendez MF |title=The neuropsychiatric aspects of boxing |journal=International Journal of Psychiatry in Medicine |volume=25 |issue=3 |pages=249–262 |year=1995 |pmid=8567192 |doi=
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| </ref> It shares features with Alzheimer's disease.<ref name="Jordan00">
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| {{
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| cite journal |author=Jordan BD |title=Chronic traumatic brain injury associated with boxing |journal=Seminars in Neurology |volume=20 |issue=2 |pages=179–85 |year=2000 |pmid=10946737 |doi=10.1055/s-2000-9826
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| </ref>
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| ===Second-impact syndrome===
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| {{main|Second-impact syndrome}}
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| Second-impact syndrome, in which the brain swells dangerously after a minor blow, may occur in very rare cases. The condition may develop in people who receive a second blow days or weeks after an initial concussion, before its symptoms have gone away.<ref name="Bowen03"/> No one is certain of the cause of this often fatal complication, but it is commonly thought that the swelling occurs because the brain's [[arteriole]]s lose the ability to regulate their diameter, causing a loss of control over cerebral blood flow.<ref name=moser/> As the brain [[swelling|swells]], intracranial pressure rapidly rises.<ref name="CookSchweer"/> The brain can [[brain herniation|herniate]], and the brain stem can fail within five minutes.<ref name="Bowen03"/> Except in boxing, all cases have occurred in athletes under age 20.<ref name="Team"/> Due to the very small number of documented cases, the diagnosis is controversial, and doubt exists about its validity.<ref name=McCroryP01>
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| cite journal|author=McCrory P |date=2001 |title=Does second impact syndrome exist? |journal=Clinical Journal of Sport Medicine |volume=11 |issue=3 |pages=144–149 |pmid=11495318
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| </ref>
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| ==Related Chapters== | | ==Related Chapters== |
| *[[Post-concussion syndrome]] | | *[[Post-concussion syndrome]] |
| | *[[Second-impact syndrome]] |
| | *[[Dementia pugilistica]] |
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| == References ==
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| {{Reflist|2}}
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| {{Injuries, other than fractures, dislocations, sprains and strains}} | | {{Injuries, other than fractures, dislocations, sprains and strains}} |