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Current  State  of  Concussion  Research  

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  

What  is  a  concussion?  

•  A  complex  pathophysiological  process  affecXng  the  brain,  induced  by  traumaXc  biomechanical  forces  – 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)  

Brain  injury:  a  major  public  health  concern  

50,000    Deaths  

235,000  HospitalizaXons  

1,111,000  Emergency  Department  Visits  

???  Receiving  Other  Medical  Care  or  No  Care  

(Langlois et al. 2004: CDC/NCIPC)

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)  

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

“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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•  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)  

Can  mouthguards  prevent  concussion?   Can  mouthguards  prevent  concussion?  

•  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  

TraumaXc  Brain  Injury  

CogniXon  

Concussion  history  

Postural  stability   Mechanism  of  injury  

Physical  exam  

Symptomatology  

Mechanism  of  injury  

• Accelerometer  research  •  Football  •  Ice  hockey  

Injury  prevenXon  

• AnXcipaXon  • InfracXons  

What  kinds  of  impacts  cause  concussion?  

Mechanism  of  injury  

Historical  biomechanics  research  

•  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                  (Holbourn,  1943  &  1945)  

Mechanism  of  injury  

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Historical  biomechanics  research  

•  Ommaya  &  Gennarelli  (1974):  – 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  

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

Mechanism  of  injury  

Recent  contemporary  work  

•  NFL  Concussion  CommiZee:  – 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  

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  

Mechanism  of  injury  

HIT  System  

•  Data  are  date-­‐  and        Xme-­‐stamped  

•  TransmiZed  to  Sideline  

   Response  System  

•  Measures:  –  Impact  severity  – LocaXon  of  impact  

Mechanism  of  injury  

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

Impact  Data  

Mechanism  of  injury  

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

Mechanism  of  injury  

Neurosurgery,  2007  

Leading  with  the  head:  Is  it  sXll  a  problem?  

•  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  

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

Mechanism  of  injury  

Neurosurgery,  2007  

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

Mechanism  of  injury  

Neurosurgery,  2007  

Mechanism  of  injury  

Case # Player

Position* Linear Magnitude (g)

Rotational acceleration

(rad/s2)

Impact Location

ΔSymptom Scores†

ΔSOT Composite‡

ΔANAM Composite‡

1 OL 60.31 5419.18 Front 2 -4.88

2 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 DB 85.10 3274.05 Top 4 4.11 0.49

8 LB 94.20 7665.10 Front No baseline data available

9 DL 99.74 8994.40 Front 27 -4.07 0.14

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

12 OL 107.07 2811.45 Top 9 -20.57 -0.76

13§5 RB 108.02 6711.00 Front 2 -17.79

14 DB 109.88 6632.77 Top 16 2.70 -0.06

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

Mechanism  of  injury  

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

Mechanism  of  injury  

JSET,  2008  

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  

•  4x  more  impacts  in  games  (~2700  vs.  ~650)  

•  Further  quesXon  proposed  injury  thresholds  (Pellman  et  al.,  2003)  

Mechanism  of  injury  

Injury  prevenXon:  AnXcipaXon  

Injury  prevenXon  

Injury  prevenXon:  AnXcipaXon  

•  AnXcipated  collisions  <  unanXcipated  collisions  •  ImplicaXons  for  collision  sports  

Injury  prevenXon  

Pediatrics,  2010  (In  Press)  

Teaching  AnXcipaXon  

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

•  Small  games  drills  

Injury  prevenXon:  InfracXon  

Checking  from  behind  

Elbowing/head  contact  Injury  prevenXon  

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•  Elbowing,  head  contact,  high  sXcking  >  legal  

•  Coaches,  players,  and  officials  share  a  responsibility  for  injury  prevenXon  

Injury  prevenXon  

MSSE,  2010  (In  Press)  

Head  impact  biomechanics  

•  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  

“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  

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  

“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

Memory Consolidation/ Retrieval

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, comprehension-checking

Fatigue Decreased arousal/ activation to engage basic attention, working memory

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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Virtual  Reality  Balance  Error  Scoring  System  

in  Virtual  Reality  

Mihalik  et  al.  J  Sport  Rehab  -­‐  2008  

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

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

Virtual  Reality  and  RehabilitaXon  

Injury  rehabilitaXon  

Virtual  reality  and  rehabilitaXon  

•  AffiliaXons  with  EA  Sports  

•  Nintendo  WiiFit  –  ImplemenXng  postural  control  as  a  part  of  a  compliant  dual  task  paradigm  

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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