ICMS 2015 Stephen E Olvey MD Associate Professor of Clinical NeurologyNeurosurgery University of MiamiMiller School of Medicine Founding Fellow FIA Institute for Motor Sports Safety and Sustainability ID: 536732
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THE USE OF IN-EAR ACCELEROMETERS TO SIGNAL CONCUSSION
ICMS 2015
Stephen
E. Olvey, M.D.
Associate Professor of Clinical Neurology/Neurosurgery
University of Miami-Miller School of Medicine
Founding Fellow FIA Institute for Motor Sports Safety and Sustainability
CMO Formula E. United
StatesSlide2Slide3
HISTORY
CHALLENGE: TO PLACE MINIATURE TRIAXIAL ACCELEROMETERS INTO
THE EAR PIECES DRIVERS USE TO COMMUNICATE WITH THEIR CREWSSlide4
HISTORY
CONCEPT INTRODUCED AT A MEETING IN SEBRING, FLORIDA, 1999
AMONG THOSE PRESENT WERE: John Melvin
Ted Knox
Doug Hill
Representatives from:
Endevco
Delphi
Racing Radios
Ford
GMSlide5
HISTORY
Project was initially met with much skepticism.
Second meeting held one month later.
Endevco
took the initiative and designed the first accelerometers.
Delphi then improved the original model and these were used in
the first tests.
Initial tests performed at Wright-Patterson AFB a short time later.Slide6
PROGRESS
In 2003, we utilized, for the first time, ear-piece accelerometers
to measure head motion with five degrees of freedom
during crashes. Data coupled with car crash recorder
data Slide7Slide8
0 Degree Rear Impact, with and without helmet TIME: 20 msSlide9
THE DEVELOPMENT OF A METHOD TO MEASURE HEAD
ACCELERATION AND MOTION IN HIGH-IMPACT CRASHES
Stephen E. Olvey, M.D.
Department of Neurological
Surgery, University of Miami
School of Medicine, Miami, Florida
Ted Knox, Ph.D.
Biodynamics and Acceleration
Branch, Air Force Research
Laboratory, Wright-Patterson Air Force Base, Ohio
Kelly A. Cohn, R.N., M.S.
The Miami Project to Cure
Paralysis, University of Miami
School of Medicine, Miami, Florida
Reprint requests:
Stephen E. Olvey, M.D.,
Department of Neurological
Surgery, University of Miami School of Medicine, 1095 N.W. 14th Terrace (D4-6), Miami, FL 33136.
Neurosurgery-2004Slide10
PLACEMENT INTO AN ACTUAL RACE CARE DELAYED DUE TO
ARGUMENTS OVER VALIDITY AND ACCURACY.
- Uncoupling
- Only 5 DOF
- Too much artifact
- Electrical Interference
ALL ARGUMENTS EVENTUALLY DISPELLED OVER 1 YEAR Slide11
INITIAL IN-CAR TESTS DONE AT MID-OHIO AND
HOMESTEAD SPEEDWAYS IN 2001-2002 WITH GOOD
RESULTS OBTAINED.
SIMULTANEOUSLY, CADAVER TESTS WERE DONE AT WAYNE
STATE UNIVERSITY COMPARING HEAD WITH EMBEDDED
ACCELS. VS. THE EAR PIECE ACCELS. < 1% VARIATION.
IN 2004, SEVERAL DRIVERS TRIALED THE SYSTEM
BY 2012, ACCELEROMETERS WERE IN ALL OF THE DRIVERS.Slide12Slide13
PARALLELL STUDIES BEGAN IN FOOTBALL IN 2003 SPURRED BY THE SIGNIFICANT INCIDENCE OF
CONCUSSION AND THE DISCOVERY OF POSSIBLE LONG TERM EFFECTS.
PELLMAN et al. USED HIGH SPEED
VIDEO FROM GAMES AND RECREATED CONCUSSIVE IMPACTS USING AN INSTRUMENTED HYBRID III DUMMY WITH THE VELOCITIES AND ANGLES OF IMPACT COMING FROM GAME FILMS AND THE CLOCK.Slide14
NFL SPONSORED STUDY
Pellman
/
Vianno
;
Neurosurgery, 2003 53(4), 799-812
25/31 Concussive
impacts; nominal linear
accel
. 79g, (SI 300, HIC 250) and peak rotational acceleration 5757 rad/s^ Values felt too conservative at the time(SI and HIC were derived in the 1960’s using linear accelerationsto determine how much force it took to cause a linear skull fx. in a cadaver skull.Rotational thresholds were determined on primates while studying concussion and DAI) Slide15
DEVELOPMENT OF THE “HITS” SYSTEM AT
VIRGINIA TECH, 2005
DUMA, ET AL: HEAD IMPACT TELEMETRY SYSTEM (HITS)
ACCELEROMETERS PLACED IN WAFERS LOCATED BETWEEN
HELMET LINER AND PLAYER’S HEAD
1. UNCOUPLING WITH HELMET AND HEAD
2. 5 DOF NOW WITH > 27,000 IMPACTS, NOMINAL INJURY VALUE REPORTED WAS 165 g WITH HIC OF 400. (MUCH > NFL STUDY) Slide16
POTENTIAL DIFFICULTY WITH BOTH HITS AND INDY SYSTEM
CONCUSSION
IS PRIMARILY CAUSED BY ROTATIONAL
INJURY
ROTATION IS NOT MEASURED WITH ONLY 5 DOF, NEED 6 DOF
IN ORDER TO GET ROTATION ABOUT THE “Z” AXISSlide17Slide18
FIRST STUDY WITH 6 DOF – 2007
(Non-peer reviewed trial)
12 ACCELEROMETERS USED IN 6 PAIRS PLACED ORTHOGONALLY INSIDE
THE HELMET TANGENTIAL TO THE HEAD COG TO GIVE 6 DOF Slide19
HISTORY
CONCEPT AT FIRST MET WITH SKEPTICISM, 1 MONTH LATER
MEETING HELD IN MIAMI WITH PLANS IN PLACE
A
EXPANSION OF THE ORIGINAL HITS SYSTEMSlide20Slide21Slide22Slide23
RESULTANT LINEAR ACCELERATIONSlide24
PEER REVIEWED STUDY WITH 6 DOF COMPLETED, 2009
-1712 IMPACTS ANLYZED (none concussed)
FOUND THAT:
Football players routinely have impacts of
< 40g and rotational accelerations of < 3000 rad/sec^
Slide25
RESULTS
(DATA REPORTED AS RESULTANTS ONLY FOR LINEAR ACCELERATIONS)
- 10% Impacts > 40g, 11impacts were > 79g
- 143 Impacts > 3000rads/sec^, 14 > 5757 rad/sec^
- Range: linear 9 – 135g; angular 107 – 9922 rad/sec^
- >3000 rad/sec^ more common around “z” axis as were
the higher linear acceleration values (No documented concussions) Slide26
INDY CAR STUDY - 2015
In-ear accelerometers have been in use in Indy Car racing in
some form since 2003.
Different companies have made improvements to the system
with a stable platform in use since 2012
I was asked to review and report on all available post –crash
data from years 2012, 2013, and 2014Slide27
METHOD
CONCUSSION IS NOT FELT TO EVER OCCUR BELOW A HEAD
ACCELERATION OF 50g. THEREFORE, ONLY CRASHES
WITH A MAXIMUM RESULTANT VALUE OF > 50g WERE
EXAMINED.
ONCE THESE CRASHES WERE TABULATED, MEDICAL
DATA WAS OBTAINED THAT REVEALED WHAT INCIDENTS
RESULTED IN A DOCUMENTED CONCUSSION TO THE DRIVER
NOTE:
Many concussions are missed!Slide28
FINDINGS
TOTAL NUMBER OF CRASHES 43
2012 = 16
2013 = 13
2014 = 14Slide29
REPORTED: 10g INCREMENTS OF HIGHEST
RECORDED RESULTANT FOR EITHER EAR
50-60g = 16 160-170 = 1
60-70g = 6 170-180 = 1
70-80g = 4 180-190 = 0
80-90g = 2 190-200 = 0
90-100 = 2 200-210 = 1
100-110 = 0 210-220 = 1
110-120 = 1 220-230 = 0
120-130 = 1 230-240 = 0
130-140 = 1 240-250 = 0140-150 = 3 > 250 = 1150-160 = 2Slide30
DOCUMENTED CONCUSSUIONS 2012-2014
TOTAL NUMBER = 5, 3 WERE WITHOUT RECORDED DATA
(usually related to the wiring)
ONLY 2 CONCUSSED DRIVERS WITH COMPLETE DATA
Slide31
SUBJECT 1
RIGHT EAR = 138.92g LEFT EAR = 154.11g
CAR WITH LINEAR RESULTANT < 5g, SUSTAINED
NO RECORDED DAMAGE; DRIVERWAS HIT IN
CHIN BY DEBRIS FROM ANOTHER CARSlide32Slide33
SUBJECT 2
RIGHT EAR RESULTANT = 168.92g, LEFT EAR = 171.93g
CAR WITH 3 AXIS RESULTANT VALUE = 68.99g
(Right frontal impact of 56 deg.)Slide34
CONCLUSIONS:
DATA FROM EAR ACCELEROMETERS IS
REPRODUCIBLE.
2. INJURY THRESHOLDS CAN BE ESTABLISHED.
3. TOO FEW CONCUSSIONS TO BE USEFUL IN
EQUIPMENT DESIGN.
4. 6 DOF NOT NEEDED TO ACCURATELY ASSESS
CONCUSSION RISK.
5. SETTING A TRIGGER THRESHOLD OF > 80g FOR MANDATORY TESTING MAKES SENSE.6. EAR ACCELS. DETECT HIGH g IMPULSIVE LOADING. Slide35Slide36
THANK YOU