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Current State  of  Concussion  Research  

What is  a  concussion?   •  A  complex  pathophysiological  process  affecXng   the  brain,  induced  by  traumaXc  biomechanical   forces  

Jason P.  Mihalik,  PhD,  CAT(C),  ATC   Assistant  Professor   Department  of  Exercise  and  Sport  Science   The  University  of  North  Carolina  at  Chapel  Hill   7th  Annual  Sports  Related  Conference  on     Concussion  &  Spine  Injury   Friday,  May  14,  2010   Fenway  Park,  Boston,  MA  

Brain injury:  a  major  public  health  concern  

50,000   Deaths  

–  Direct blow  or  impulsive  forces  transmiZed  to  head   –  Typically  results  in  rapid  onset  of  neurological   impairments   –  Concussion  is  a  funcXonal—not  structural—injury   –  May  or  may  not  include  LOC   –  Not  idenXfiable  on  standard  imaging  (CT,  MRI)      

(CIS  Guidelines,  2009)  

Costs associated  with  TBI   •  1.6  to  3.8  million  TBI  result  from  sports  each   year  (Langlois  et  al.,  2006  –  JHTR)   •  $56.3  billion  in  direct  and  indirect  costs  (Langlois  et  al.,   2004  –  CDC)  

235,000 HospitalizaXons  

•  CDC states  TBI  (specifically  its  preven5on)   must  con5nue  to  be  a  na5onal  priority  

1,111,000 Emergency  Department  Visits   ???  Receiving  Other  Medical  Care  or  No  Care   (Langlois et al. 2004: CDC/NCIPC)

“I thought mouthguards were designed to prevent concussion”

Can mouthguards  prevent  concussion?   •  Does  wearing  a  mouthguard  affect  incidence  of  concussion?   –  No  significant  relaXonship  between  wearing  a  MG  and  incidence  of   concussion  in  games  or  pracXces;  type  of  MG  also  did  not  play  a  role   (Momsen  et  al.  UNC  Thesis-­‐2004)  

•  How effecXve  is  “brain  pad”  mouthguard?   –  Random  clinical  trial  comparing  WIPSS  Brain  Pad  to  mouthguard  of   choice   –  Result:  no  difference  in  number  of  concussions  between  Brain  Pad  MG   and  MG  of  choice  (Barbic  et  al.  CJSM-­‐2005)  

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Can mouthguards  prevent  concussion?  

Can mouthguards  prevent  concussion?   •  Custom  vs.  non-­‐custom  mouthguards?  

–  No associaXon  between  mouthguard  type  and   number  of  concussions  in  all  games  and  pracXces   (Wisniewski  et  al.  Dent  Traumatol-­‐2004)  

•  Does wearing  a  mouthguard  reduce  the   neurocogniXve  deficits  that  follow  concussion?  

–  180 student-­‐athletes  were  assessed  following  MTBI   –  Use  of  mouthguard  does  liZle  to  reduce  the  acute   severity  of  neurocogniXve  dysfuncXon  and  onset  of   symptoms  following  sports-­‐related  head  trauma   (Mihalik  et  al.  Dent  Traumatol-­‐2006)  

•  A lack  of  evidence  for  mouthguard  use   prevenXng  concussion  (Knapik  et  al.  Sports  Med-­‐2007)   •  Do  these  findings  make  sense  clinically?   Biomechanically?   •  Mouthguards  are  effecXve  in  reducing   maxillofacial  and  dental  trauma  and  should  be   worn  for  that  reason  

TBI: A  mulXfaceted  condiXon  

Postural stability  

Mechanism of   injury  

Concussion history  

CogniXon

Mechanism of  injury  

•  Accelerometer research   •  Football   •  Ice  hockey  

Physical exam  

TraumaXc Brain   Injury  

Injury prevenXon  

Symptomatology

• AnXcipaXon • InfracXons  

Historical biomechanics  research  

What kinds  of  impacts  cause  concussion?  

•  Used animal  models:  cats,  dogs,  and  monkeys   –  Pre-­‐1940,  impacts  imparted  to  fixed  heads   –  1940s  marked  pendulum  hammers  and  suspended   subjects  (Denny-­‐Brown  &  Russell,  1941)   –  High-­‐speed  cinephotography  (Pudenz  &  Shelden,  1946)  

•  Physical model:  wax  skull/gelaXnous  brain   –  Developed  to  eliminate  need  for  animal  model   –  IniXal  descripXon  rotaXonal  acceleraXon  was  likely   needed  to  produce  corXcal  lesions  and  concussion     Mechanism   of  injury  

(Holbourn,  1943  &  1945)  

Mechanism of  injury  

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Historical biomechanics  research   •  Ommaya  &  Gennarelli  (1974):  

Recent contemporary  work   •  NFL  Concussion  CommiZee:  

–  Ooen credited  for  rotaXonal  acceleraXon   –  Important  addiXon:  direct  head  impacts  not   needed   –  No  injuries  resulted  from  linear  impacts   –  2-­‐12  min  LOC  in  13  monkeys    rotaXonal  MOI  

–  Laboratory reconstrucXon  of  concussive  injuries   captured  on  video  (Pellman  et  al.  2003)   •  Limited  number  of  cases  reconstructed  (31/182)   •  Injuries  likely  to  occur  if  lin  acc  exceeds  70-­‐75  g  

•  1 never  awoke   •  2  others  died  within  1  hour  of  the  impact   Mechanism   of  injury  

Mechanism of  injury  

HIT System   •  Helmets  fiZed  with  six  single-­‐axis  accelerometers,   baZery  pack,  and  telemetry  unit   •  Spring-­‐loaded  ensuring  contact  with  head   •  Data  collected  at  1  kHz  over  40  ms  

HIT System   •  Data  are  date-­‐  and        Xme-­‐stamped   •  TransmiZed  to  Sideline      Response  System   •  Measures:   –  Impact  severity   –  LocaXon  of  impact  

Mechanism of  injury  

Mechanism of  injury  

Impact Data   •  31  total  impacts  for  both  sessions   •  Between  2.87  g  to  97.97  g  (mean  =  28.95  g)  

Mechanism of  injury  

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Leading with  the  head:  Is  it  sXll  a  problem?  

•  Helmets-­‐only pracXce  >  games   •  Top  of  helmet  impacts  >  all  other  areas  

Mechanism of  injury  

•  In short:  yes   •  20%  of  all  impacts  occurred  to  top  of  head   •  Our  data  suggest  that  players  were  more  likely   to  sustain  an  impact  of  >80  g  to  top  of  the   head  than:   –  Right  side  (8.5X)   –  Leo  side  (6.54X)   –  Front  (7.08X)   –  Back  (2.43X)   Mechanism   of  injury  

Neurosurgery, 2007  

•  Impacts exceeding  theoreXcal  thresholds  did   not  result  in  deficits  on  clinical  measures  

Mechanism of  injury  

•  No relaXonship  between  severity  of  head   impact  and  acute  clinical  outcomes  

Mechanism of  injury  

Neurosurgery, 2007  

Neurosurgery, 2007  

Case #

Player Position*

1 2

Mechanism of  injury  

Linear Magnitude (g)

Rotational acceleration (rad/s2)

Impact Location

ΔSymptom Scores†

ΔSOT Composite‡

OL

60.31

5419.18

Front

2

-4.88

ΔANAM Composite‡

RB

60.51

163.35

Top

12

-19.15

-0.20

3

LB

63.84

5923.27

Front

8

-15.68

-0.35

4

WR

66.36

5573.42

Front

23

3.85

5

RB

77.68

3637.48

Top

8

-29.18

0.22

6

DB

84.07

5299.57

Front

7

-2.25

-0.26

7

4.11

0.49

DB

85.10

3274.05

Top

8

LB

94.20

7665.10

Front

9

DL

99.74

8994.40

Front

4

10

OL

100.36

1085.26

Top

0

-2.00

1.01

11§3

LB

102.39

6837.62

Right

30

-60.01

-1.56 -0.76

No baseline data available 27

-4.07

0.14

12

OL

107.07

2811.45

Top

9

-20.57

13§5

RB

108.02

6711.00

Front

2

-17.79

14

DB

109.88

6632.77

Top

16

2.70

15§14

DB

115.50

2303.63

Top

2

-1.49

16

DL

119.23

7974.22

Right

12

2.89

0.12

17

LB

157.50

1020.00

Front

14

0.71

0.42

18

WR

168.71

15397.07

Back

13

7.33

0.79

19

RB

173.22

4762.74

Top

32

8.08

-0.06

Mechanism of  injury  

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ImplicaXons to  youth  athleXcs   •  Youth  ice  hockey  players  sustain  impacts   similar  to  Division  I  football  players   –  20  to  23  g,  depending  on  posiXon  (Mihalik,  Guskiewicz,  et  al.,   2007)   –  Of  great  concern:  smaller  size  and  younger  age  

•  Impacts same  as  college  football  players   •  Top  of  head  hits  problemaXc  in  youth  hockey  

•  4x more  impacts  in  games  (~2700  vs.  ~650)   •  Further  quesXon  proposed  injury  thresholds   (Pellman  et  al.,  2003)  

Mechanism of  injury  

Mechanism of  injury  

JSET, 2008  

Injury prevenXon:  AnXcipaXon  

Injury prevenXon:  AnXcipaXon  

•  AnXcipated collisions  <  unanXcipated  collisions   •  ImplicaXons  for  collision  sports   Injury   prevenXon  

Injury prevenXon  

Pediatrics, 2010  (In  Press)  

Teaching AnXcipaXon  

Injury prevenXon:  InfracXon  

•  Coaching techniques   –  PracXce:  game-­‐related  contact  drills   •  Small  games  drills  

Checking from  behind  

Injury prevenXon  

Elbowing/head contact  

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Head impact  biomechanics  

•  Elbowing, head  contact,  high  sXcking  >  legal   •  Coaches,  players,  and  officials  share  a   responsibility  for  injury  prevenXon  

•  •  •  •  • 

Effect of  special  teams  vs.  offense  and  defense   Cervical  muscle  strength   Player  aggression   ConXnued  descripXve  exploraXon   ConXnued  injury  study  

•  Inclusion of  different  populaXons:   –  Female,  lacrosse,  military   –  Neuroimaging  at  all  levels  

Injury prevenXon  

MSSE, 2010  (In  Press)  

“Should my  child  rest  or  go  to  school?”   •  95  concussed  student  athletes  categorized  into  5   groups:   –  No  school  or  exercise  acXvity   –  School  acXvity  only   –  School  acXvity  and  light  acXvity  at  home  (i.e.  mowing   lawn,  slow  jogging)   –  School  and  sports  pracXce   –  School  and  sports  game  

•  Neuropsychological tesXng  and  symptom  status   were  analyzed  

“Should my  child  go  to  school?”   Managing  FuncXonal  Academic  Deficits   Neuropsychological Deficit

Functional School Problem

Management Strategy

Short focus on lecture, classwork, homework “Working” Memory

Holding instructions in mind, reading comprehension, math calculation, writing

Repetition, written instructions, use of calculator, short reading passages

Retaining new information, accessing learned info when needed

Smaller chunks to learn, recognition cues

Processing Speed

Keep pace with work demand, process verbal information effectively

Extended time, slow down verbal info, comprehensionchecking

Fatigue

Decreased arousal/ activation to engage basic attention, working memory

Memory Consolidation/ Retrieval

Rest or  no  rest?   •  Highest  level  of  acXvity  following  concussion   resulted  in  worse  outcomes   •  Intermediate  levels  of  acXvity  had  the  best   outcomes  (But  also  likely  the  least  severely  injured)   •  Absolute  rest  resulted  in  worse  outcomes  than   intermediate  levels  of  ac5vity   (Majerske,  Mihalik  et  al.  JAT-­‐2008)  

•  Is there  a  potenXal  for  Xmed  exerXon  or   rehabilitaXon  strategies?  Area  for  future   research  

Can we  use  technology  to  assess  and   rehabilitate  concussion?   •  Theory:  virtual  reality  environments  provide  a   mechanism  to  sXmulate,  but  not  endanger,   athletes  with  concussion   •  Different  types  of  VR  exist   –  Cave  AutomaXc  Virtual  Environment  (CAVE)   –  Head-­‐mount  display*   –  Stereo  projecXon  

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Balance Error  Scoring  System   in  Virtual  Reality  

Virtual Reality  

Mihalik et  al.  J  Sport  Rehab  -­‐  2008  

Does  the  weight  of  the  HMD  affect   balance?   –  Main  finding:  it  does  not        

Virtual Reality  and  RehabilitaXon  

(Mihalik  et  al.,  J  Sport  Rehab  -­‐  2008)  

Virtual reality  and  rehabilitaXon   •  AffiliaXons  with  EA  Sports   •  Nintendo  WiiFit   –  ImplemenXng  postural  control  as  a  part  of  a   compliant  dual  task  paradigm  

Injury rehabilitaXon  

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What is  to  come   •  EducaXon   •  EducaXon   •  EducaXon   –  Coaching  iniXaXves   –  Parental  educaXon   –  Player  development   –  Official  educaXonals  intervenXons   –  Physician  awareness   –  CAT(C)/ATC  training  

Concluding thoughts…   •  Clinicians  must  conXnue  to  ask  quesXons   •  Researchers  must  strive  to  answer  RQs   •  There  is  sXll  much  unknown  about   concussion   •  Concussion  management  is  not  an  auto-­‐pilot   funcXon   •  Litmus  tests  to  detect  injury  do  not  exist  

Acknowledgments

Jason P. Mihalik, PhD, CAT(C), ATC Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center The University of North Carolina E-mail: jmihalik@email.unc.edu Office: 919.843.2014 Lab: 919.962.0409 Fax: 919.962.0489

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Mihalik_2010_Fenway_Concussion_BW  

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