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Headeandespineeinjuries
Document developed in collaboration with Prof. Karin Brolin, Prof. Johan Davidsson and Prof. Mats Svensson from Chalmers University
28th International CourseTransport Research Injury Prevention Program Course
Indian Institute of Technology Delhi
December 2018
Jacobo Antona-Makoshi, PhD.
Whateiseessentialetoeprotect?
• Life supporting functions– Brain– Cervical spine (above C3)
• Quadriplegia above T1• Paraplegia below T1
Societalecosts
• Estimations of social costs per body region injured in vehicle crashes, including medical costs, emergency services, lost work wages and loss of quality of life, among others, show that Head and Spinal Injuries comprise the two most costly (Zaloshnja et al. 2004, Blincoe et al. 2015)
Principalepartseofetheenervousesystem
• Central nervous system (CNS):– brain– spinal cord
• Peripheral nervous system (PNS):– numerous, paired nerves joining CNS with
different parts of the body– ganglia - clusters of nerve cells
Fig.e45.03(TEeArt)Nervous system
Centralnervoussystem
BrainSpinalcord
Peripheralnervoussystem
Somatic(voluntary)
nervous system
Motorpathways
Sensorypathways
Autonomic(involuntary)
nervous system
Sympatheticdivision
Parasympatheticdivision
Sensory pathways
Motor pathways
AISeexamplesebyebodyeregion
AIS Head Thorax Abdomen and pelvic contents
Spine Extremities and bony pelvis
1 Headache or dizziness
Single rib fracture
Abdominal wall: superficial
Acute strain (no fracture or disl.)
Toe fracture
2 Unconscious < 1 hr.; linear fracture
2-3 rib fracture; sternum fracture
Spleen kidney or liver: laceration or contusion
Minor fracture without any cord involvement
Tibia, pelvis or patella: simple fracture
3 Unconscious 1-6 hrs.; depressed fracture
≥ 4 rib fracture; 2-3 rib fracture with hemoth. or pneumoth.
Spleen or kidney: major laceration
Ruptured disc with nerve root damage
Knee dislocation; femur fracture
AIS Head Thorax Abdomen and pelvic contents
Spine Extremities and bony pelvis
4 Unconscious 6-24 hrs.; open fracture
≥4 rib fracture with hemoth. Or pneumoth.; flail chest
Liver major laceration
Incomplete cord syndrome
Amputation or crush obove knee pelvis crush (closed)
5 Unconscious> 24 hrs.; large hematoma
Aorta laceration (partial transection)
Kidney, liver or colon rupture
quadriplegia Pelvis crush (open)
AISeexamplesebyebodyeregion
HeadeInjuries
Howedoeweeprotectetheehead?
HeadeInjuries
Do not teach things people already know (Dinesh Mohan, Dec 2017)
BraineInjuries
Herculano et al 2012www.brainmuseum.org
Mammalebraineevolution
Corpus callosum
Medulla oblongataBreathing, Heart Rate,Blood Pressure
PonsMotor control Sensory analysisSleep
HypothalamusTemperature, Emotions, Hunger, Thirst
ThalamusSensory processingMovementLateral ventricle
Optic recess
HippocampusMemory Learning
Brain Neuronal Tracts Brain Vasculature
Brainecomplexity
WhateisesoespecialeabouteTraumatice
BraineInjurye(TBI)?
• Extremely mild bump can damage the brain• Bones often recover but TBI frequently causes permanent harm• TBI cannot be understood with dead brains• The brain is incompressible
Incompressibleebrain?
Courtesy of Lee Gabler
AcuteeSymptomsefollowingeTBI
Mild Brain Injury• Brief period of
unconsciousness• Headache• Confusion• Dizziness• Sensory problems• Mood changes• Concentration problems
Moderate to Severe• Persistent headache• Nausea• Spasm• Dilation pupils• Slurred speech• Weakness or numbness• Loss of coordination• Increased confusion
LongetermesymptomsefromeTBI
• Trouble remembering, concentrating, making decisions, and controlling impulses
• Suffer from serious motor, sensory, and emotional impairments
• Not all TBI-related disabilities are readily apparent to others (“The silent epidemic“)
• … depression, drug abuse, suicide
Traumatic Brain Injury
Diffuse Brain Injury
Concussion
Hematoma
Focal Brain Injury
Contusion
Diffuse Axonal Injury
Traumatic Brain Injury
Diffuse Brain Injury
Concussion
Hematoma
Focal Brain Injury
Contusion
Diffuse Axonal Injury
• Coup• Contre-coup• Gliding
Contusions
• Bruise of the brain common at inferior surfaces of frontal and temporal lobes
• Frequently accompany other TBI of higher severity• Mechanism: Brain contact with rigid intracranial structures.
Traumatic Brain Injury
Diffuse Brain Injury
Concussion
Hematoma
Focal Brain Injury
Contusion
Diffuse Axonal Injury
• Epidural• Subdural• Subarachnoidal• Intracerebal
Epidural hematoma Acute Subdural hematoma
Subarachnoid hematoma Intracerebral hematoma
• Artery ruptures between dura and skull
• Substantial mortality risk• More common in children
and teenagers.• Mechanism: mostly temporal
bone fracture
• Veins rupture• Blood accumulates between dura and
arachnoid.• Mortality rate 30-60%• Mechanisms:
– Penetrating objects and bone fragments
– Large contusions– Tearing of bridging veins
• Artery ruptures. • Bleeding into the cerebrospinal fluid of the
sub-arachnoid space.• Permanent brain damage from ischemia or
from the presence of hematoma.• Mechanism: Rotational acceleration in
conjunction with aneurysm (?)
• Blood in central parts of the brain.
• Mortality rate 6-72%• Blood irritates the brain
tissues, causing swelling or hematoma
• Mechanism: Laceration, shear deformation (?)
Traumatic Brain Injury
Diffuse Brain Injury
Concussion
Hematoma
Focal Brain Injury
Contusion
Diffuse Axonal Injury
Concussion
• Loss of consciousness or confusion for a short period• CT/MRI normal but patient may have headache,
cognitive problems, etc• Anterograde and retrograde amnesia • Duration of amnesia correlates with injury severity • Rarely fatal• Post concussion syndrome, memory problems,
dizziness, and depression• Mechanism: Head rotational and linear acceleration (?)
Davante Adams ‘Moderate’ Concussion https://www.youtube.com/watch?v=WOkI_Blee-s
Traumatic Brain Injury
Diffuse Brain Injury
Concussion
Hematoma
Focal Brain Injury
Contusion
Diffuse Axonal Injury
DiffuseeAxonaleInjurye(DAI)
• Lesions in white matter (corpus callosum and brainstem)• Unconscious and vegetative state (21%)• Frequently fatal (30%) • Secondary biochemical cascades largely responsible for the damage
to axons.• Mechanism: shearing forces due to rotational acceleration stretching
axons
Brain tissue
NASS-CDS database publicly available
TBIeinereal-worldecarecrashes
Increasing TBI Severity
TB
I cat
egor
ies
top 3
FrequencyeofeoccupantsewitheTBICrash Year 2001-15, Model Year 2001-15, Light Vehicles, Occupant Age 15+
Antona-Makoshi et al. 2018 Accident Analysis and Prevention
Life-threateningeTBIeriskebyeyear
No clear decrease of life-threatening injuries is observed with time
Antona-Makoshi et al. 2018 Accident Analysis and Prevention
TBIeriskeandeseatbelt
Beltuse reduces risk of all TBI categories
Antona-Makoshi et al. 2018 Accident Analysis and Prevention
TBIeriskeandespeed
The risk of all TBI categories increases with crash severity
Cars with AEB Cars without AEB
Reduction in risk of striking another vehicle in a rear-end crash
vs.
Fildes et al. 2015
• AEB very effective in preventing crashes• A shift in crash severity is expected in the coming years
AutonomouseEmergencyeBraking
TBIeriskeandespeed
The risk of all TBI categories increases with crash severity
Belted elderly occupants in frontal crashes are (10 times) more likely to sustain an Acute Subdural Hematoma than non-elderly.
SubDuraleHematomaeinjuryeriskefactors
Antona-Makoshi et al. 2018 Accident Analysis and Prevention
Belted female occupants in frontal crashes are (1.5 times) more likely to sustain a Moderate Concussion than belted males.
Concussioneinjuryeriskefactors
Antona-Makoshi et al. 2018 Accident Analysis and Prevention
Adopted occupant protection strategies are insufficient to achieve significant decreases in risk of both life-threatening brain injuries and concussions. Further effort is needed to develop occupant and injury
specific strategies for the prevention of brain injuries. Future traffic injury prevention strategies need to prioritize life-threatening vasculature brain
injuries, particularly in elderly occupants, and concussion injuries, particularly in female occupants.
TBIeinereal-worldecarecrashes
InjuryeBiomechanics
• Analyze real-world data
Scientific discipline that applies the principles of mechanics to human (surrogate) subjects with the objective of clarifying injury mechanisms
and quantifying injury tolerances
Injury Reduction
• Clarify injury mechanisms• Develop tools, injury criteria & tolerances• Evaluate Safety
Injuryemechanismefromedynamiceloading
• Direct contact– Linear acceleration
• Deformation• Stress waves• Pressure gradients
–Negative pressure–Cavitations–Shear strains
– Rotational acceleration• Relative motion between
skull and brain• Shear in brain tissue
• Non-contact– Inertia properties
• Relative motion between skull and brain
Radial impact Oblique impact
Radial vs. oblique impact
Kleiven, ESV2007
Courtesy of Lee Gabler
BiomechanicalebraineinjuryecriteriaCriteria areeneededethat can be used with crash tests dummies (or human models) to predict mild, moderate and severe TBIs which mechanisms (including head rotation) are not necessarily associated with skull fractures.
Courtesy of Lee Gabler
Headekinematicsemetrics
Takhounts et al 2013 Gabler et al 2018
Gabler et al 2017 Yanaoka et al 2015
Takahashi & Yanaoka 2017
Miyazaki et al 2018
Antona-Makoshi et al 2016
Kikuchi et al 2016
Kimpara & Iwamoto 2012Kimpara & Iwamoto 2012
UVA MB
EBrIC
UVAeheadeimpactedatabasee(N=1,595)
Gabler, L. F., Crandall, J. R., & Panzer, M. B. (2018). Development of a Metric for Predicting Brain Strain Responses Using HeadKinematics.Annals of biomedical engineering, 1-14.
for the evaluation of head kinematics metrics
Courtesy of Matthew Panzer
TBIecriteriaeandeassociatederiskefunctions
Volunteer experiments
Animal experiments
Sports impacts reconstructions
Methodsetoeestablishebraineinjuryetolerances
Real-world TBI data
TBIecriteriaeandeassociatederiskefunctions
UVAeExperimentaleInjuryeDatabase
Military Volunteer Football Laboratory Reconstruction
Animal Tests
Increasing Injury SeverityNo InjuryLife-threatening
Injury
Ewing et al. 1972~1975Sanchez et al. 2017
Pellman et al. 2003Sanchez et al. 2018
Gennarelli et al. 1980Ono et al. 1980
for the development of TBI risk curves
Courtesy of Taotao Wu
Animal experiments
Injury Criteria and thresholds for humans
Injury thresholds crude scaling
(Holbourn 1943)
Numerical model of animal test
Brain tissue risk functions
Numerical model of human
Head kinematics scaling
(Takhounts et al. 2013)
Applicability of animal data to humans
TBI mechanisms in (past) head impact experiments with monkeys
Simulation of monkey frontal head impact test
•24 impacts•8 specimens
•10 concussions
•19 impacts•7 specimens
•9 concussions
TBI injury risk curves
A kinematics brain injury criterion & thresholds
Brain Injury Thresholds Surface (BITS)
Monkey and human brains are similar at thetissue biomechanical level
2 padding materials, 3 impactors, 3 Impact speeds (4, 6 and 8 m/s)
Simulation of human head impacts
Transfer to humans via brain FE simulations
< 10% probability of concussion ~ 60% probability of concussion
TBI thresholds considering translational acceleration, rotational acceleration and duration
Du
ratio
n (
ms)
1. Helmets, seatbelts and speed control!2. Crash mitigation technologies (AEB)3. Brain injury criteria and risk functions
Life-threatening bleeding injuries (elderly)Concussions (women)Combination of human and animal data (applicability)
4. Testing tools (e.g dummies, FE models) and methods for safety evaluation
Howedoeweepreventebraineinjuries?
SPINEeINJURY
Spinaleanatomy
• Cervical spine (neck)
• Thoracic spine– Ribs
• Lumbar spine
• Sacrum• Coccyx
Neckeanatomy
Peripheralnervoussystem
Directionaledependence
Strengtheofetrabecularebone
(b)(a)
Compressive Tensile
Theeintervertebraledisc• Purposes:
– Damping– Restrict relative translations between the vertebrae– Allow for some rotation
• Hydrofilic gel– 90% to 70% water
• Collagen fibers in ground substance– Fiber direction ± 60º
Theeintervertebraledisc
αο α1
F
FvertebraAF
NP
cartilage endplate
(a) (b)
(c) (d)
• 10 times stiffer in compression than torsion, shear or flexion.
• The almost incompressible properties of the NP result in tensile loading of the collagen fibers when the disc is compressed.
• Rate dependent properties
• Viscoelasticity (fluid flow)
0
0,1
0 50 100 150
Saline stored Boiled
Ten
sile
load
(kN
)
Time (s)
(1)
(2)
(3)
(4)
Collagen & Elastin fibers Elastin fibers
Tensileetestingeofeligament
Tens
ile lo
ad [k
N]
Kneeeligamenteundereloading
unloaded
loaded
Young’s modulus
(MPa)
Yield strain (%)
Strain at failure (%)
Stress at failure (MPa)
Collagen 500 10-20 45-125
Elastin 3 130
Ground substance
3
Ligaments 20 25 > 100 20
Tendons 50-100 4 10 60
Apatit crystals 165,000
Trabecular bone 50-500 1-10 2-100
Cortical bone 15,000-21,000
1-2 100-200
Rubber 1.4 0.499
Oak 10,000 0.2 5 100
Steel 200,000 0.3 1 500
EpidemiologySevereespinalecordeinjury,eAISe3+
• 10.000 cases/year in the US–Motor vehicle 54%–Fall 16%–Diving 12%
• 20.000 cases/year in India–Traffic 45%–Fall 35%
• male:female 3:1• 20-40 years of age
EpidemiologySevereespinalecordeinjury,eAISe3+
• In modern cars– Roll-over – Unbelted all directions – Forward facing children age <2 years
• Motorcyclist, mopeds and bikes– All accident types
Ineautomotiveecrashes…
• If unbelted head contact the windscreen in frontal crashes–Axial compression–Shear loading –Bending
• Minor soft tissue neck injuries due to inertia–Axial tension–Shear loading–Bending
Severeeneckeloade- examples
Bad design
Out of position airbag injuries
Pedestrian accident
Compressioneloading
BURST FRACTUREIncreasing load Dislocation of facet
Unstable neck
JEFFERSON’S FRACTUREUnstable
Flexion-compressione
loading
Dislocation most often OC-C1
Tensioneextensioneloads
Hangman
http://www.mvd.chalmers.se/~mys/
Whiplash Associated Disorders (WAD)AIS 1
Prevention
Diagnosis
Treatment
Tension-extension loading, caused by inertia loading of the head.
Injury mechanism ?
Injuryemechanismse
• Facet joints ?–Pain (>40%)
• Muscle ?–Good prognosis
• CNS ?–Dorsal nerve root ganglion injury due to pressure
wave• Ligament ?• Disc ?
Still not know – research ongoing
Pain sensitization.
Whiplashemotioneofetheecervicale
spine
77
During a rear impact
The S-Shape of the cervical spine is: � characterised as a nonphysiologic curvature� hyphothesised to cause WADs
Grauer et al., 1997, Whiplash produces and S-Shape curvature of the neck with hyperextension at lower levels.
Result from rear impact sled tests with head-neck PMHSsInitial Position
http://www.mvd.chalmers.se/~mys/
Experimental studies
• Human subjects• Animal models
Operating-table
Head-
BackrestPull-rod
Straps
Rod
Linear displacement transducer
Angular displacement transducers
z-acc.
x-acc.
Pull-force
X
Z
Coordinate-system
http://www.mvd.chalmers.se/~mys/
Crash Dummies
BioRID II
RID 3D
Carlson A., Addressing female whiplash injury protection, PhD thesis, 2012
MenNormalized to 1
Carlson A., Addressing female whiplash injury protection, PhD thesis, 2012
Women
81
Cervicalspine
Thoracicspine
Lumbarspine
Female Male
Sato F, Female and Male Whole Spinal Alignment and Cervical Kinematic Responses in Rear Impacts, Lic. thesis, 2017
Toolserepresentingefemales
https://www.chalmers.se/en/projects/Pages/OpenHBM.aspx
Neckeinjuryecriteria
• AIS3+– Nij =Fz/Fint+My/Mint
• AIS1– NIC =0.2 arel + vrel
2
– Nkm = Fx/Fint+My/Mint
NijedummyevaluesproposedebyeNHTSA
Kleinberger M et.al. Development of improved injury criteria for the assessment of advanced automotive restraint systems - II, NHTSA report, Nov. 1999.
Nij=Fz/Fint+My/Mint
NIC = 0.2 arel + vrel2
arel = aT1 - ahead
vrel = vT1 - vhead
NICe=eNeckeInjuryeCriterion
ahead, Vhead
aT1, VT1
50% risk: NIC=25 m2/s2
NIC=15 m2/s2
Hypothesis: Pressure aberrations inside the spinal canal.
Nkm Neckeprotectionecriterion
load case Intercept value
Extension moment 47.5 Nm
Flexion moment 88.1 Nm
Shear 845 N
Hypothesis: Linear combination of shear and y-moment is responsible for relevant neck loading
Neckeinjuryecriteria
• AIS3+– Nij =Fz/Fint+My/Mint
• AIS1– NIC =0.2 arel + vrel
2
– Nkm = Fx/Fint+My/Mint
Kleinberger M et.al. Development of improved injury criteria for the assessment of advanced automotive restraint systems , NHTSA report, Sept. 1998.
Boström O, Svensson M, Aldman B, Hansson H, Håland Y, Lövsund P, Seeman T, Suneson A, Säljö A, Örtengren T (1996): A new neck injury criterion candidate based on injury findings in the cervical spinal ganglia after experimental neck extension trauma, Proc. IRCOBI Conf., pp. 123-136
Schmitt K-U, Muser M, Niederer P (2001): A new neck injury criterion candidate for rear-end collisions taking into account shear forces and bending moments, Proc. ESV Conf.
Schmitt K-U, Muser M, Walz F, Niederer P (2002): Nkm — a proposal for a neck protection criterion for low speed rear-end impacts, Traffic Injury Prevention, Vol. 3 (2), pp. 117-126
Kullgren A, Eriksson L, Krafft M, Boström O (2003): Validation of neck injury criteria using reconstructed real-life rear-end crashes with recorded crash pulses, Proc. 18th ESV Conf
Reflection
Whatedideyouelearn?
Whatedideyouefindeinteresting?