Department of Neurosurgery Department of Neurosurgery Thomas A. Gennarelli, M.D. Professor and Chair Department of Neurosurgery Medical College of Wisconsin Milwaukee, Wisconsin, USA [email protected]Thomas A. Gennarelli, M.D. Thomas A. Gennarelli, M.D. Professor and Chair Professor and Chair Department of Neurosurgery Department of Neurosurgery Medical College of Wisconsin Medical College of Wisconsin Milwaukee, Wisconsin, USA Milwaukee, Wisconsin, USA [email protected][email protected]Head Injuries: How to Protect What Snell Conference on HIC May 6, 2005 Head Injuries: How to Protect What Head Injuries: How to Protect What Snell Conference on HIC Snell Conference on HIC May 6, 2005 May 6, 2005
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Head Injuries: How to Protect What...SDH main injury 4 5 9 EDH 4 22 8 ICH 3 12 Department of Neurosurgery Skull Fracture Incidence Percent Skull Fracture Incidence Percent Occupants
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Department of NeurosurgeryDepartment of Neurosurgery
Head Injuries: How to Protect WhatHead Injuries: How to Protect What
Snell Conference on HICSnell Conference on HIC
May 6, 2005May 6, 2005
Department of NeurosurgeryDepartment of Neurosurgery
INJURY:INJURY:INJURY:
The result of the application of mechanical energy above the ability of the tissue to withstand it without anatomical or physiological alteration.
The result of the application The result of the application of mechanical energy above of mechanical energy above the ability of the tissue to the ability of the tissue to withstand it without withstand it without anatomical or physiological anatomical or physiological alteration.alteration.
Department of NeurosurgeryDepartment of Neurosurgery
BRAIN INJURY IS NOT UNIDIMENSIONAL!!
BRAIN INJURY IS NOT BRAIN INJURY IS NOT UNIDIMENSIONAL!!UNIDIMENSIONAL!!
So is one tolerance reasonable?????So is one tolerance reasonable?????
Department of NeurosurgeryDepartment of Neurosurgery
What are we trying to prevent?What are we trying to prevent?What are we trying to prevent?
•Which TBI are “acceptible?”•Which TBI are unacceptibl;e?•Are these the same for all
circumstances?•Given the advances in the last
50 years. Don’t we have to lower the bar and prevent more TBI?
••Which TBI are “Which TBI are “acceptibleacceptible?”?”••Which TBI are Which TBI are unacceptibl;eunacceptibl;e??••Are these the same for all Are these the same for all
circumstances?circumstances?••Given the advances in the last Given the advances in the last
50 years. Don’t we have to 50 years. Don’t we have to lower the bar and prevent more lower the bar and prevent more TBI?TBI?
Department of NeurosurgeryDepartment of Neurosurgery
Mortality of severe TBIMortality of severe TBIMortality of severe TBI
0
1020
3040
50
6070
80
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
Mor
talit
y
• Uniform injury descriptors; improved care; trauma care systems
• GCS: Teasdale ,Jennett 1974
• Widespread adoption of GCS, Langfitt, Gennarelli 1982
• Uniform injury descriptors; improved care; trauma care systems
• GCS: Teasdale ,Jennett 1974
• Widespread adoption of GCS, Langfitt, Gennarelli 1982
Department of NeurosurgeryDepartment of Neurosurgery
Importance of Biomechanics Importance of Biomechanics Importance of Biomechanics
• Shift of TBI type• Shift of TBI
severity• Reduction of
mortality• Potential of virtual
elimination of severe TBI in certain situations
•• Shift of TBI typeShift of TBI type•• Shift of TBI Shift of TBI
severityseverity•• Reduction of Reduction of
mortalitymortality•• Potential of virtual Potential of virtual
elimination of elimination of severe TBI in severe TBI in certain situationscertain situations
1950
1960
1970
1980
1990
2000
2010
2020
Focal FrontalDBI Frontal
1950
1960
1970
1980
1990
2000
2010
2020
Focal SideDbi Side
Vehicular Head Injuries
Department of NeurosurgeryDepartment of Neurosurgery
Number of Vehicles with AirbagsNumber of Vehicles with AirbagsNumber of Vehicles with Airbags
0
10
20
30
40
50
60
70
87 88 89 90 91 92 93 94 95 96 97 98 9920
00
Year
Cars
Trucks
Millions
% of Vehicle Fleet
Department of NeurosurgeryDepartment of Neurosurgery
Future of TBIFuture of TBIFuture of TBI• The chances of getting an
AIS 4-6 head injury when restrained with seat belt and airbag are very small in a frontal crash .. 0.14%. So if all 1.5M frontal occupants had SB+AB:•1.5 *0.14% =2100/yr = 1
per hospital per year
•• The chances of getting an The chances of getting an AIS 4AIS 4--6 head injury when 6 head injury when restrained with seat belt restrained with seat belt and airbag are very small and airbag are very small in a frontal crash .. 0.14%. in a frontal crash .. 0.14%. So if all 1.5M frontal So if all 1.5M frontal occupants had SB+AB:occupants had SB+AB:•1.5 *0.14% =2100/yr = 1
per hospital per year
1.53%
0.54%
0.15% 0.14%
0.00%0.20%0.40%0.60%0.80%1.00%1.20%1.40%1.60%
NONE AB SB BOTH
Serious Head Injuries (AIS 4-6)
•If a serious head injury occurs, it will be at far higher crash speeds than with other restraint systems.
••If a serious head injury If a serious head injury occurs, it will be at far higher occurs, it will be at far higher crash speeds than with other crash speeds than with other restraint systems.restraint systems.
Department of NeurosurgeryDepartment of Neurosurgery
Minor TBI will be more important
Minor TBI will be more Minor TBI will be more importantimportant
0%
20%
40%
60%
80%
100%
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
Freq of minorFreq of Severe
`
So, do we need to think about preventing So, do we need to think about preventing mTBImTBI??
Department of NeurosurgeryDepartment of Neurosurgery
TYPES OF HEAD INJURYTYPES OF HEAD INJURYTYPES OF HEAD INJURY• SCALP LACERATIONS• SKULL FRACTURES• FOCAL BRAIN INJURIES
Department of NeurosurgeryDepartment of Neurosurgery
Relation of Tolerances to Adjectival Descriptors of Diffuse
Brain Injury
Relation of Tolerances to Relation of Tolerances to Adjectival Descriptors of Diffuse Adjectival Descriptors of Diffuse
Brain InjuryBrain Injury
0
4500
12000
1450016500
3000
8000
R2 = 0.9897
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
None
Mild Concussi
on
Classical
Consussio
n
Severe Concu
ssion
Mild DAI
Moderate DAI
Severe DAI
ActualCalculatedLinear (Actual)
Fig 2. Results of using scaled tolerances values from Margulies to equivalentadjectival descriptors (actual = Margulies values) and interpolating values for mild and severe concussion (calculated)
0
2877.8
5755.6
8633.4
11511.2
14389y = 2877.8xR2 = 0.9864
0
2000
4000
6000
8000
10000
12000
14000
16000
0 1 2 3 4 5 6
AIS
rad/
sec2
ActualComputed
Fig 1. Results of using scaled tolerances values from Margulies to equivalent AIS values (actual; AIS = 0, 2,4,5) and interpolating values for AIS values 1,3 (computed)
Relation of Diffuse Brain Injury Tolerances to AISRelation of Diffuse Brain Injury Tolerances to AIS
Department of NeurosurgeryDepartment of Neurosurgery
Department of NeurosurgeryDepartment of Neurosurgery
King: 2003King: 2003King: 2003•• At least for MTBI, the best predictor for At least for MTBI, the best predictor for
injury is neither linear nor angular injury is neither linear nor angular accelerationacceleration
•• It is the product of strain and strain rateIt is the product of strain and strain rate•• This may be controversial but it is This may be controversial but it is
biomechanically reasonable because biomechanically reasonable because brain response governs injury, not the brain response governs injury, not the inputinput
Department of NeurosurgeryDepartment of Neurosurgery
What are we trying to prevent?What are we trying to prevent?What are we trying to prevent?
•Which TBI are “acceptible?”•Which TBI are unacceptibl;e?•Are these the same for all
circumstances?•Given the advances in the last
50 years. Don’t we have to lower the bar and prevent more TBI?
••Which TBI are “Which TBI are “acceptibleacceptible?”?”••Which TBI are Which TBI are unacceptibl;eunacceptibl;e??••Are these the same for all Are these the same for all
circumstances?circumstances?••Given the advances in the last Given the advances in the last
50 years. Don’t we have to 50 years. Don’t we have to lower the bar and prevent more lower the bar and prevent more TBI?TBI?
Department of NeurosurgeryDepartment of Neurosurgery
Total Protection from TBITotal Protection from TBI
Department of NeurosurgeryDepartment of Neurosurgery
Department of NeurosurgeryDepartment of Neurosurgery