Wisconsin CIREN Team PowerPoint Presentation - August 2002

SLIDE 1:
Carotid Artery Dissections
Presented by
	Karen Brasel MD MPH
	Frank Pintar PhD.
	Dale Halloway

Departments of Neurosurgery and Trauma/Critical Care
Medical College of Wisconsin  Froedtert Hospital CIREN Center and VA Medical Center

SLIDE 2:
Blunt Carotid Artery Injuries Causes
- MVC
- Airplane crashes
- Sports events (parachute jump, ski crash)
- Strangulation
- Chiropractic manipulation
- Assaults
- Nose blowing
- Neck turning while leading a parade

SLIDE 3:
Blunt Carotid Artery Injuries Mechanism
Mechanism
- direct blow
- hyperflexion
- hyperextension

Source
- seatbelt
- other object
- airbag

SLIDE 4:
Blunt Carotid Artery Injuries Epidemiology
Incidence
- highly variable
- different populations
	symptomatic
	asymptomatic
	high-risk
- influence of aggressive screening protocols

SLIDE 5:
Blunt Carotid Artery Injuries
Associated injuries
- Head injuries 65%
- Facial fxs 60%
- Thoracic injuries 51%
- Basilar skull fxs 32%
- Cervical fxs 5%
- 9% with NO associated injuries

SLIDE 6:
Blunt Carotid Artery Injuries
Delayed symptoms
- mean 12 hours after admission
- >25% develop after 12 hours
- outcome worse when diagnosis delayed

SLIDE 7:
Blunt Carotid Artery Injuries
Outcome

Mortality 
- 11-57% 
- Shock, GCS ? 8 increase mortality
- Lowest with asymptomatic patients

Morbidity 
- 10-37%
- GCS less than/equal to 8, thrombosis increase risk of deterioration

SLIDE 8:
Blunt Carotid Artery Injuries
Outcome
- Stroke rate related to injury Grade
- Outcome not related to injury Grade I-IV
- greater than or equal to 50% Grade I heal 
- Majority Grade III, IV unchanged
- Risk of follow-up angiography

SLIDE 9:
Blunt Carotid Artery Injuries
Summary

Epidemiology
- 0.1 to 1.1% all blunt trauma admissions
- increases 4-10 x with screening
- 40 - 80% MVC
- 20 - 40% bilateral

SLIDE 10:
Blunt Carotid Artery Injuries
Summary
- Delayed onset of sx
- Injury from intimal tear, subsequent emboli
- Majority asymptomatic
- Low incidence, high morbidity/mortality
- Treatment unclear

SLIDE 11:
Blunt Carotid Artery Injuries
Summary

Clinical questions
- Who to study?
- How to study?
  * angiography
  * MRA
  * ultrasound
- How to treat?
  * antiplatelet
  * anticoagulation
  * stent
  * operative

SLIDE 12:
Search of NASS Data
AlS Codes Beginning 3202 
- Nineteen internal carotid artery injuries 1993-2000 
- Unknown injury source
- Ejected occupants
- Injuries coded NFS
- Laceration (perforation, puncture)
- Three potentially good dissection cases

<Note: AIS injury coding incorporated into NASS data beginning 1993>

SLIDE 13:
Review of NASS Data
Good Cases
- One rollover; Source = roof
- One frontal pole impact - Source = belt webbing
- One full-frontal impact - Source = steering wheel

SLIDE 14:
Search of CIREN Cases 
- 1992 Saturn - 14-year-old female right-front passenger 
- 2000 Ford Focus - 43-year-old female driver     
- 1994 Toyota Corolla - 34-year-old female right-front passenger  

SLIDE 15:
1992 Saturn Offset-frontal Impact
1 o'clock impact
left carotid artery dissection with lucid interval of 20 days [source = belt webbing]

SLIDE 16:
1994 Toyota Corolla Side Impact
3 o'clock impact
left carotid artery dissection detectedd 8 hours after admission [source = unknown]

SLIDE 17:
2000 Ford Focus Oblique Rear Impact
7 o'clock impat
source = hyperextension over seat back; diagnosed 12-24 hours after crash

SLIDE 18:
1993 Nissan Altima 4-door sedan vs 1991 Chevrolet Blazer 2-door 4X4 SUV

Department of Neurosurgery
Medical College of Wisconsin
and VA Medical Center

SLIDE 19:
Case Occupant
- Driver
- 38-year-old male
- 180 cm (5 11), 80 kg (176 lb)
- 2-point shoulder belt worn
- Manual lap-belt not worn
- Driver airbag deployed

SLIDE 20:
Crash Overview
The case vehicle (red) was traveling southbound on a four-lane highway with a speed limit of 65 mph (105 kph).  Vehicle two (blue) was traveling northbound on the same roadway.  It was snowing and the roadway was covered lightly with snow.  Vehicle two went out of control and entered a counterclockwise rotation and crossed the median and entered the path of the case vehicle. 

 
SLIDE 21:
Crash Overview
The impact caused the case vehicle to rotate clockwise and depart the road off of the west shoulder.  Vehicle two continued to rotate counterclockwise and came to rest on the west shoulder.

SLIDE 22:
Scene Photo

SLIDE 23:
Path of Case Vehicle (photo)

SLIDE 24:
Path of Vehicle Two (photo)

SLIDE 25:
11 oclock PDOF 
CDC  11-FLEW-4

SLIDE 26:
1993 Nissan Altima 
24 mph Delta V (ROLD MISS) - 29 mph EBS

SLIDE 27- 34:
1993 Nissan Altima
- 42 cm of direct damage
- 80 cm of maximum crush at left-front bumper corner
- Approximate height of bumper/frame-rail of V2
- Left wheelbase reduced 28 cm
- Effect of the geometric mis-match between the two vehicles
- 32 cm longitudinal intrusion at left IP; 23 cm of measured steering wheel intrusion. An estimated 8 cm repositioned toward front of vehicle during extrication
- 2 cm steering wheel rim deformation 
- steering Wheel out of round
 

SLIDES 35-41:
1993 Nissan Altima
- Shear capsules compressed. Probably extrication related.
- Scuff mark extrication related per commander of
rescue unit
- 2-point motorized automatic belt mouse jammed in retracted position prior to impact - used as a manual belt
- Lap belt not used
- Post-crash blood deposits on driver-side airbag
- Head Contact with door frame
- 7 cm long dent
- Knee Bolster Cover

SLIDE 42:
Significant Crash Elements
- Angle of impact
- Geometric mismatch
- Extent of intrusion
- Lack of three-point restraint 

SLIDE 43:
Kinematically Significant Injuries

CASE VEHICLE: 1993 Nissan
TYPE: Altima 4-door sedan
OCCUPANT: Driver - 38-year-old male
STATURE: 180 cm (5ft 11in)	MASS: 80kg (176lb)
RESTRAINTS: 2-pt belt worn w/o lap belt; airbag deployed

- abrasion, right forehead
- thrombosis, left and right interna carotid arteries
- fracture, comminuted left femoral neck
- fracture, open and comminuted left patella

SLIDE 44:
Case Occupant Presenting History
- 38-year-old male
- GCS at scene: 12
- GCS at 17:00: 14
- GCS at 18:38: 13
- GCS at 19:55: 7
- Intubated and chemically paralyzed on admission

SLIDE 45:
Case Occupant Highest AIS Injuries
- Thrombosis, right CCA with neurological deficit = AIS 4
- Comminuted, displaced fracture, left femoral neck = AIS 3
- Grade I liver laceration = AIS 2
- ISS = 29

SLIDES 46-47:
1993 Nissan Altima
Carotid Artery Injuries

SLIDES 48-49:
1993 Nissan Altima
	Left Femoral neck FX

SLIDE 50:
Carotid Artery Anatomy

SLIDES 51-52:
Microanatomy of an Artery
Media: middle layer; primarily muscular tissue; aligned transversely around vessel

Adventitia:  outer layer; primarily connective tissue; can stretch up to 100% of original length

Glycocalyx: lubricant layer on inner surface; may contribute to non-thrombogenic properties of intact endothelium

Intima:  inner layer; primarily endothelial cells; aligned in tile-like layout, elongated in direction of blood flow

SLIDE 53:
Micro-Biomechanics of Artery

- Adventitia (outer layer) high tolerance to local stretch; will rarely rupture

- Media (middle layer) less tolerant to stretch since muscle alignment not longitudinal

- Intima (inner layer) least tolerant to stretch with tightly packed cells 

SLIDE 54:
Carotid Artery Dissection
with Occlusion

Disruption of Intima and maybe media layers cause Thrombosis

SLIDE 55:
Mechanisms of Injury
Carotid Artery Dissection

Direct Blow: Pinching
Distractive load: Tension, Stretching

SLIDE 56:
Mechanisms of Injury
Pinching Mechanism
- Foreign object impinges
  * Kids: toothbrush, other objects in mouth
  * Strangulation
- High riding seatbelt on neck?

SLIDE 57:
Mechanisms of Injury
Stretching Mechanism

Bilateral CAD: uniform hyperextension of head-neck
- Rear impact: extension over headrest
- Frontal impact: Forehead impeded, chest moves forward
  * Forehead into windshield
  * Forehead into top of steering wheel
  * Forehead into top of header
- Frontal impact: Airbag unfolding (timing must be right)

SLIDE 58:
Mechanism of Injury
Bilateral CAD (diagram)

SLIDE 59:
Mechanisms of Injury
Stretching Mechanism
Unilateral CAD: non-uniform extension of head-neck
- Offset crash: front-lateral forehead 
- Head turned before crash
- Lateral impact: hyper lateral extension

SLIDE 60:
SUMMARY 
Carotid Artery Dissections
- NASS missing cases? 
	Lucid interval a problem
- CIREN plays major role in identifying
- Mechanism of Injury:  look for hyper-extension of head-neck complex
- Treatment:  pre-screening asymptomatic patients ?