Helmets and Neck Injuries in Fatal Motorcycle Crashes James V. - - PowerPoint PPT Presentation

Helmets and Neck Injuries in Fatal Motorcycle Crashes

James V. Ouellet David R. Thom Terry A. Smith

Examination of vehicles and crash scene

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Reconstruction

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Motorcycle Crash speed

10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90 Cumulative Percent Motorcycle Crash Speed, mph No Helmet (n=241) Helmet (n=59)

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Distribution of Most Severe Somatic (Below- the-Neck) Injury in Fatal Motorcycle Crashes

2 2 10 23 28 15 20 2 16 7 25 27 14 10 5 10 15 20 25 30

None Minor Moderate Serious Severe Critical Maximum

Percent Severity of Most Severe Somatic Injury Helmet (n=60) No Helmet (n=244)

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Fatality Rate as a Function of Most Severe Somatic Injury, Combined USC & Thailand Data

1 3 33 89 2 1 3 15 90 10 20 30 40 50 60 70 80 90 100

None Minor Moderate Serious Severe Critical Maximum

Percent Severity of Most Severe Somatic Injury Helmet (n=774) No Helmet (n=1065)

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Fatality Rate as a Function of Most Severe Somatic Injury, Combined USC & Thailand Data

1 3 33 89 2 1 3 15 90 10 20 30 40 50 60 70 80 90 100

None Minor Moderate Serious Severe Critical Maximum

Percent Severity of Most Severe Somatic Injury Helmet (n=774) No Helmet (n=1065)

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Neck Injury Type and Frequency, All 304 Riders

10 20 30 40 50 60 70 80 90

Throat Neck Muscle Nerve plexus Carotid Sheath Vertebral Arteries Blood Vessel C3-C7 Subluxation, Dislocation C1-C2 Subluxation, Dislocation C3-C7 Fracture C1-C2 Fracture Spinal Cord

Helmet Worn (n=60) No Helmet (n=244)

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Neck Injury Type and Frequency among Riders with Most Severe Somatic AIS>3

10 20 30 40 50 60 70 80 90

Throat Neck Muscle Other Hemorrhage Carotid Sheath Vertebral Artery C3-C7 Subluxation, Dislocation C1-C2 Subluxation, Dislocation Spinal Subluxation, Dislocation C3-C7 Fracture C1-C2 Fracture Spinal Fracture Spinal Cord No Helmet (n=124) Helmet (n=38)

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13.8 59.7 15.4 6.5 34.7 21.1 65.8 18.4 10.5 31.6 10 20 30 40 50 60 70 80 90 100 C3-C7 Subluxation or Dislocation C1-C2 Subluxation or Dislocation C3-C7 Fracture C1-C2 Fracture Spinal Cord Percent Helmet Worn (n=38) No Helmet (n=124) χ2 = .672, p = .413 χ2 = .069, p = .793 χ2 = .672, p = .413 χ2 = 2.158, p = .142 χ2 = 7.182, p = .007

Spinal Cord & Column Injuries, All 304 Riders

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12.3 61.5 23.6 9.4 31.1 26.7 71.7 30.0 8.3 36.7 10 20 30 40 50 60 70 80 90 100 C3-C7 Subluxation

• r Dislocation

C1-C2 Subluxation

• r Dislocation

C3-C7 Fracture C1-C2 Fracture Spinal Cord Percent Helmet Worn (n=60) No Helmet (n=244) χ2 = .125, p = .724 χ2 = .704, p = .401 χ2 = .190, p = .663 χ2 = .457, p = .499 χ2 = 1.157, p = .282

Spinal Cord & Column Injuries, Riders with AIS>3

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15.6 57 44.7 48.4 45.5 76.2 20 66.7 60 65 50 83.3 10 20 30 40 50 60 70 80 90 100 Throat Neck Muscle Nerve plexus Carotid Sheath Vertebral Arteries Any Blood Vessel Percent Helmet (n=60) No Helmet (n=244) χ2 = 1.400, p = .237 χ2 = .394, p = .530 χ2 = 4.535, p = .033 χ2 = 1.871, p = .171 χ2 = .687, p = .407 χ2 = 5.399, p = .021

Neck Soft Tissue Injuries, All 304 Riders

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12.5 55 36.7 43.3 45.8 72.5 27.3 59.1 40.9 50 50 72.7 10 20 30 40 50 60 70 80 90 100 Throat Neck Muscle Nerve plexus Carotid Sheath Vertebral Arteries Any Blood Vessel Percent Helmet (n=38) No Helmet (n=124) χ2 = 0.000, p = .982 χ2 = .130, p = .719 χ2 = .143, p = .705 χ2 = .126, p = .723 Fisher Exact test, p = .698 χ2 = 335, p = .563

Neck Soft Tissue Injuries, Riders with Somatic AIS<4

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Effect of Helmet Weight

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1 5 6 6 2 5 6 7 1 2 4 6 4 1 1 3

2 4 6 8 10 12 14 Frequency Helmet weight, pounds

Spinal cord injury + No spinal cord injury

Helmet Weight and Spinal Cord Injury

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Helmet Weight and Cervical Spine Fracture

1 5 7 7 4 6 6 7 1 2 3 5 2 1 3

2 4 6 8 10 12 14

Frequency Helmet weight, pounds

C-Spine fractured No C-spine Fx

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Helmet Weight and C1-C2 Subluxation or Dislocation

1 2 4 1 3 2 4 2 6 8 8 5 3 5 6 2 4 6 8 10 12 14

Frequency Helmet weight, pounds

C1-C2 Sublux/Disloc No C1-C2 Sublux/Disloc

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Helmet Weight and C3-C7 Subluxation or Dislocation

2 4 8 9 4 5 5 7 3 2 3 2 2 3 2 4 6 8 10 12 14

Frequency Helmet weight, pounds

C3-C7 Sublux/Disloc No C3-C7 Sublux/Disloc

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Vertebral Artery Anatomy

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Helmet Weight and Vertebral Artery Injury

1 2 4 5 4 4 4 6 1 5 6 7 2 2 3 4 2 4 6 8 10 12 14

Frequency Helmet weight, pounds

Vertebral artery injury No injury

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Carotid Sheath Contents: Common Carotid Artery, Internal Jugular Vein & Vagus Nerve

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Carotid Sheath Contents: Common Carotid Artery, Internal Jugular Vein & Vagus Nerve

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Helmet Weight and Carotid Sheath Hemorrhage

2 6 5 1 1 1 5 2 5 4 7 5 5 6 5 2 4 6 8 10 12 14

Frequency Helmet weight, pounds

Carotid injury No Carotid Sheath Injury

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Helmet Weight and Hemorrhage Surrounding NerveTrunks or Nerve Plexes

1 1 6 6 2 1 3 4 1 6 4 6 4 5 4 6 2 4 6 8 10 12 14

Frequency Helmet weight, pounds

Nerve / plexus injury None

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Conclusions 1

• 1. About 5% of crashes are fatal. They are NOT

representative of the motorcycle crash population.

• 2. Unhelmeted riders are 2-3 times as likely to die in

a crash as helmeted riders.

• 3. Unhelmeted riders are more likely to die in a

crash despite having only relatively minor below- the-neck injuries.

• 4. Helmets are especially effective in preventing

death in serious-to-severe crashes.

• 5. Helmet users showed statistically insignificant

increases in many injuries reported here.

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Conclusions 2

• 6. The risk of spinal cord injuries or cervical spine

fractures in these fatal crashes was no higher among helmet users than non-users.

• 7. Three kinds of injuries were more common among

helmeted riders:

• a. Cervical spine subluxation and dislocation
• b. Hemorrhage in the carotid sheath
• c. Hemorrhage around nerve trunks and plexes
• 8. Helmet weight had no consistent effect on any

injury except perhaps hemorrhage in the carotid sheath and around nerve trunks and plexes.

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Thank You

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