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 2

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Reconstruction 4

Motorcycle Crash speed 100 90 80 Cumulative Percent No Helmet (n=241) 70 Helmet (n=59) 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 Motorcycle Crash Speed, mph 5

Distribution of Most Severe Somatic (Below- the-Neck) Injury in Fatal Motorcycle Crashes 30 27 28 25 Helmet (n=60) 25 No Helmet (n=244) 23 20 20 Percent 16 15 15 14 10 10 10 7 5 2 2 2 0 None Minor Moderate Serious Severe Critical Maximum Severity of Most Severe Somatic Injury 6

Fatality Rate as a Function of Most Severe Somatic Injury, Combined USC & Thailand Data 100 90 89 90 80 70 Helmet (n=774) Percent 60 No Helmet (n=1065) 50 40 33 30 20 15 10 3 2 3 1 1 0 0 0 None Minor Moderate Serious Severe Critical Maximum Severity of Most Severe Somatic Injury 7

Fatality Rate as a Function of Most Severe Somatic Injury, Combined USC & Thailand Data 100 90 89 90 Helmet (n=774) 80 No Helmet (n=1065) 70 Percent 60 50 40 33 30 20 15 10 3 2 3 1 1 0 0 0 None Minor Moderate Serious Severe Critical Maximum Severity of Most Severe Somatic Injury 8

Neck Injury Type and Frequency, All 304 Riders Spinal Cord Helmet Worn (n=60) C1-C2 Fracture No Helmet (n=244) C3-C7 Fracture C1-C2 Subluxation, Dislocation C3-C7 Subluxation, Dislocation Blood Vessel Vertebral Arteries Carotid Sheath Nerve plexus Neck Muscle Throat 0 10 20 30 40 50 60 70 80 90 9

Neck Injury Type and Frequency among Riders with Most Severe Somatic AIS>3 Spinal Cord Spinal Fracture No Helmet (n=124) C1-C2 Fracture Helmet (n=38) C3-C7 Fracture Spinal Subluxation, Dislocation C1-C2 Subluxation, Dislocation C3-C7 Subluxation, Dislocation Vertebral Artery Carotid Sheath Other Hemorrhage Neck Muscle Throat 0 10 20 30 40 50 60 70 80 90 10

Spinal Cord & Column Injuries, All 304 Riders 31.6 χ 2 = .672, p = .413 Spinal Cord 34.7 10.5 Helmet Worn (n=38) χ 2 = .069, p = .793 C1-C2 Fracture 6.5 No Helmet (n=124) 18.4 χ 2 = .672, p = .413 C3-C7 Fracture 15.4 65.8 C1-C2 Subluxation or χ 2 = 2.158, p = .142 Dislocation 59.7 21.1 C3-C7 Subluxation or χ 2 = 7.182, p = .007 Dislocation 13.8 0 10 20 30 40 50 60 70 80 90 100 Percent 11

Spinal Cord & Column Injuries, Riders with AIS>3 36.7 χ 2 = .125, p = .724 Spinal Cord 31.1 8.3 Helmet Worn (n=60) C1-C2 Fracture χ 2 = .704, p = .401 9.4 No Helmet (n=244) 30.0 C3-C7 Fracture χ 2 = .190, p = .663 23.6 71.7 C1-C2 Subluxation χ 2 = .457, p = .499 or Dislocation 61.5 26.7 C3-C7 Subluxation χ 2 = 1.157, p = .282 or Dislocation 12.3 0 10 20 30 40 50 60 70 80 90 100 Percent 12

Neck Soft Tissue Injuries, All 304 Riders 83.3 χ 2 = 1.400, p = .237 Any Blood Vessel 76.2 Helmet (n=60) 50 Vertebral Arteries χ 2 = .394, p = .530 45.5 No Helmet (n=244) 65 χ 2 = 5.399, p = .021 Carotid Sheath 48.4 60 χ 2 = 4.535, p = .033 Nerve plexus 44.7 66.7 χ 2 = 1.871, p = .171 Neck Muscle 57 20 χ 2 = .687, p = .407 Throat 15.6 0 10 20 30 40 50 60 70 80 90 100 Percent 13

Neck Soft Tissue Injuries, Riders with Somatic AIS<4 72.7 χ 2 = 0.000, p = .982 Any Blood Vessel 72.5 50 Vertebral Arteries χ 2 = .130, p = .719 Helmet (n=38) 45.8 No Helmet (n=124) 50 χ 2 = 335, p = .563 Carotid Sheath 43.3 40.9 Nerve plexus χ 2 = .143, p = .705 36.7 59.1 χ 2 = .126, p = .723 Neck Muscle 55 27.3 Throat Fisher Exact test, p = .698 12.5 0 10 20 30 40 50 60 70 80 90 100 Percent 14

Effect of Helmet Weight 15

Helmet Weight and Spinal Cord Injury 14 Spinal cord injury + 12 No spinal cord injury 10 6 3 Frequency 8 4 1 6 2 1 4 4 7 6 6 6 5 5 2 1 2 1 0 Helmet weight, pounds 16

Helmet Weight and Cervical Spine Fracture 14 C-Spine fractured 12 No C-spine Fx 10 5 3 3 Frequency 8 1 6 2 2 4 7 7 7 6 6 5 2 4 1 1 0 Helmet weight, pounds 17

Helmet Weight and C1-C2 Subluxation or Dislocation 14 C1-C2 Sublux/Disloc 12 No C1-C2 Sublux/Disloc 10 Frequency 8 8 6 6 8 3 5 4 6 5 2 4 4 3 2 2 2 1 1 0 Helmet weight, pounds 18

Helmet Weight and C3-C7 Subluxation or Dislocation 14 C3-C7 Sublux/Disloc 12 No C3-C7 Sublux/Disloc 3 10 2 3 Frequency 8 6 2 3 2 9 4 8 7 5 5 2 4 4 2 0 Helmet weight, pounds 19

Vertebral Artery Anatomy 20

Helmet Weight and Vertebral Artery Injury 14 Vertebral artery injury 12 No injury 10 Frequency 7 8 4 6 6 3 2 2 5 4 6 5 2 4 4 4 4 1 2 1 0 Helmet weight, pounds 21

Carotid Sheath Contents: Common Carotid Artery, Internal Jugular Vein & Vagus Nerve 22

Carotid Sheath Contents: Common Carotid Artery, Internal Jugular Vein & Vagus Nerve 23

Helmet Weight and Carotid Sheath Hemorrhage 14 Carotid injury 12 No Carotid Sheath Injury 10 Frequency 7 8 4 5 6 5 4 6 5 5 6 5 5 2 2 2 1 1 1 0 Helmet weight, pounds 24

Helmet Weight and Hemorrhage Surrounding NerveTrunks or Nerve Plexes 14 Nerve / plexus injury 12 None 10 6 Frequency 8 4 6 6 4 4 6 4 5 6 6 2 4 1 3 2 1 1 1 0 Helmet weight, pounds 25

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. 26

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. 27 27

Thank You 28