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 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 o’clock 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 ?