Concussion
The Basic Science
Arturo Aguilar MD
Boston University
June 1, 2011
Disclosure
Neither I, Arturo Aguilar, nor any family
members, have any relevant financial
relationships to be discussed, directly or
indirectly, referred to or illustrated with or
without recognition within the presentation
Objectives

- History

- Incidence

- Definition

- Pathology

- Symptoms / Diagnosis

- Grading

- Risk
History



A short lived period of posttraumatic neurologic
dysfunction followed by full recovery has been
described for over 3,000 years.1
From the Latin term cerebrum commotum2
“...paralysis of cerebral function” Dr. LaFrancus
(13th century)2
Incidence




Approximately 1.6-3.8 million concussions each
year in the U.S.3
10% of college football players sustain brain
injuries each season.4
Concussions are the second most common
injury in college football and women's soccer.
Fourth most common in men's soccer, field
hockey, women's volleyball.5
Up to 85% of concussions go undiagnosed.6
Consensus Guidelines
International Symposia on Concussion in Sport
(Vienna 2001, Prague 2004, Zurich 2008)7,9


IIHF, FIFA, IOC
Physicians, Neuropsychologists, sports
administrators, basic scientists

Original research, previous guidelines

Level C evidence
Definition

A complex pathophysiological process affecting
the brain, induced by traumatic biomechanical
forces. [There are] several common features...
(Consensus Statement of Concussion in Sport 3rd International
Conference on Concussion in Sport. Zurich 2008)
7
Definition
Common Features



Concussion may be caused either by a direct
blow to the head, face, neck, or elsewhere on
the body with an “impulsive” force transmitted to
the head.
Typically results in the rapid onset of short
lived impairment of neurologic function that
resolves spontaneously.
...acute clinical symptoms largely reflect a
functional disturbance rather than a structural
injury.
7
Definition



Concussion results in a graded set of clinical
symptoms that...may not involve loss of
consciousness.
Resolution of clinical/cognitive symptoms
typically follows a sequential course [but]...in a
small percentage of cases, post-concussive
symptoms may be prolonged.
No abnormality seen on standard structural
neuroimaging.
1
Pathophysiology



No existing animal or other experimental model
that accurately reflects a sporting concussive
injury.
In animal models there is a complex cascade of
biochemical, metabolic, and gene expression
changes.
Unclear application to humans

Anesthetized animals-blurs acute effects

Symptom interpretation

Different mechanical factors of smaller brains
Diagnosis /
Observed
8
Symptoms
Reported

Dazed, stunned
Headache, pressure

Confusion, forgetful
Nausea, vomiting
Clumsy/balance
issues
Dizzy
Speaks slowly
photo/phono-phobia
Loss of
consciousness
Foggy, fatigue, hazy
Mood, behavior,
personality changes
Feeling down/not right




Blurred vision
Memory/focus issues
Clinical Domains of
7,8
Concussion
Symptoms
Physical
Signs
Behavioral
Signs
Cognitive
Impairment
Sleep
Disturbance
headache
Loss of
Consciousness
Irritability
Slowed Reaction
Time
Drowsiness
Nausea/vomiting
Amnesia
Depression
Difficulty
Concentrating
Insomnia
Dizzy
Balance Issues
Anxiety
Memory Loss
Fatigue
Tonic Clonic
Activity
More Emotional
Foggy Feeling
Personality
Changes
Forgetful
Blurred Vision
Photo/PhonoPhobia
Dazed / Stunned
Not Feeling
Diagnosis
5
Difficulty
“Perhaps the most challenging aspect of
managing...concussion[s] is recognizing the
injury, especially in [those] with no obvious
signs that a concussion has actually
occurred.”(NATA Position Statement: Management of Sport
Related Concussions. 2004)

Rationalizing symptoms

Uneducated regarding the seriousness

Fear of limiting participation

Popular media around professional return to
play
Concussion
7
Grading
25 concussion grading / management systems
(2004)4,11
Symptoms, LOC
Lack evidence

Abandon grading scales and (simple vs
complex) classifications. (Zurich 2008)
Second Impact Syndrome
Concussion and Risk:
7
Fact or Fiction
-If you had loss of consciousness you had a more
severe concussion.
Fiction
-The majority of concussion symptoms last 7-10
days.
Fact
-If you have had a concussion in the past your
next is likely to last longer.
Fact
Concussion and Risk:
3,9
Fact or Fiction
-Once you sustain a concussion, you are 3-4x
more likely to sustain a concussion again.
Fact
-If you have the A4 allele of the Apo E4 gene, you
are more likely to sustain a concussion than
those who do not.
Fiction
-
Concussion and Risk:
3,9
Fact or Fiction
-If you wear the proper protective gear you are
less likely to sustain a concussion.
Fiction
-By modifying some rules in sport, we may be
able to reduce the risk of concussion in athletes.
Possibly
Summary
-Concussions are common
-Diagnosis: Mechanism + sign/symptom
-Think about the reasons we miss concussions
-There is a consensus statement to help guide
diagnosis and management
-There are still many things we don't know yet,
these are just guidelines.
References
1 McCrory P, Johnston K., Mohtadi N., Meeuwisse W” Evidence-Based Review of Sport-Related Concussion: Basic Science” Clinical
Journal of Sports Medicine. (2005): Vol15 Num 6
2 Solomon G, Johnston K, Lovell M. The Heads-Up on Sport Concussion. United Graphics, USA. 2006
3 Davis G, Iversion G, Guskiewicz K, Ptito A, Johnston K. “Contributions of neuroimaging, balance testing, electrophysiology and blood
markers to the assessment of sport-related concussion” British Journal of Sports Medicine. (2009); 43
4 Asplund C, McKeag D, Olsen C. “Sport-Related Concussion. Factors Associated With Prolonged Return to Play” Clinical Journal of
Sports Medicine (2004); 14:339-343
5 Guskiewicz K, Bruce S, Cantu R, Ferrara M, Kelly J, McCrea M, Putukian M, McLeod T. “National Athletic Trainers' Association
Position Statement: Management of Sport-Related Concussion” Journal of Athletic Training (2004); 39(3):280-297
6 Harmon MD, Kimberly “Assessment and Management of Concussion in Sports.” American Family Physician. (1999) ; 60:887-89
7 McCrory, Johnston, Meeuwisse, Aubry, Cantu, Dvorak, Kelly “Summary and Agreement Statement of the 3nd International
Conference on Concussion in Sport, Zurich, 2008.” Clinical Journal of Sports Medicine. (2009) Vol 19 Number 3
8 “Heads Up Facts for Physicians About Mild Traumatic Brain Injury (MTBI)” U.S. Department of Health and Human Services.
http://www.cdc.gov/ncipc/tbi/Facts_for_Physicians_booklet.pdf
9 McCrory, Johnston, Meeuwisse, Aubry, Cantu, Dvorak, Graf-Baumann, Kelly, Lovell, Schamasch “Summary and Agreement
Statement of the 2nd International Conference on Concussion in Sport, Prague 2004.” Clinical Journal of Sports Medicine. (2005)
Vol 15, Number 2
10 Kissick J, Johnston K. “Return to Play After concussion” Clinical Journal of Sports Medicine. (2005); 15:426-431