documented wounding effects in Comments on “Ballistics: a 4,7 primer for the surgeon” peripheral nerves. A series of experiments15,10,11,12,13 studied Michael Courtney Ballistics Testing Group, P.O. Box 24, West pigs shot in the thigh. High-speed Point, NY 10996 pressure transducers were implanted in [email protected] the thigh, abdomen, neck, and brain. These experiments determined that Amy Courtney ballistic pressure waves over 400 kPa Department of Physics, United States (59 psi) reach the contralateral thigh and Military Academy, West Point, NY 10996 waves as large as 300 kPa (44 psi) can reach the brain.12 Electron microscopy Published as: Injury, 2008 Aug; 39(8): p 964-5. revealed damage in peripheral nerves, DOI: 10.1016/j.injury.2008.03.020 spinal cord, and brain. A similar experiment18 in dogs found significant Abstract: damage in both the hypothalamus and In response to a published assertion to the contrary, this paper briefly reviews many hippocampus regions of the brain due to studies that document remote wounding remote effects of the ballistic pressure effects of ballistic pressure waves including wave. A recent paper reviews links experiments in pigs and dogs that find brain between traumatic brain injury and injury resulting from animal models shot in ballistic pressure waves.1 the thigh and case studies in humans that document both remote brain and spinal cord Case studies in human patients also injuries ascribed to ballistic pressure waves. document pressure wave effects in the central nervous system. In 1941, a The authors of “Ballistics: a primer for 17 soldier received a bullet wound near but the surgeon” write: not directly impacting the brain.16 The patient experienced acute epileptic In addition to the transverse, low- symptoms which reappeared nearly 50 frequency wave that emanates from the years later with secondary projectile as it passes through tissue, generalisation. The authors attribute which creates the temporary cavity, this pathology to the pressure wave. there are also high-frequency, low- amplitude stress waves that are Several studies reveal remote pressure produced in front of the projectile. wave wounding in the spinal cord.8,9,14 These compressive waves are similar to For example, a woman shot with a 9mm the shock waves seen in front of high- handgun experienced specific speed aircraft. It is not clear what effect neurological symptoms in the spine these waves have on wounding remote from the wound channel.9 This characteristics of a projectile, but it is wounding was explained by focusing of likely that they play a small role in the pressure wave on the spinal cord producing permanent injury. (similar to the way a lens can focus light waves). In contrast to this assertion, many studies document remote wounding Finally, the formula given for drag force17 effects of ballistic pressure waves. is incorrect and not found in the citation.6 Early studies revealed that the The drag force magnitude is:2,5 magnitudes of the oscillating high- 1 2 frequency ballistic pressure wave could Fd  Cd  d  A v , be over 1000 kPa (147 psi)3 and 2 where Fd is the drag force, Cd is the drag extremity Impact: Part II. Distant Effects on coefficient, d is the fluid density, A is the Central Nervous System. A Light and Electron Microscopic Study on Pigs. J the cross sectional area of the projectile, Trauma 1990;30:295-306. and v is the projectile velocity. 14. Taylor RG, Gleave JRW. Incomplete Spinal Cord Injuries. J Bone Joint Surg Br References 1957;B39:438-450. 15. Tikka S, Cederberg A, Rokkanen P. Remote effects of pressure waves in missile trauma: 1. Courtney A, Courtney M. Links between the intra-abdominal pressure changes in traumatic brain injury and ballistic pressure anaesthetized pigs wounded in one thigh. waves originating in the thoracic cavity and Acta Chir Scand Suppl 1982; 508:167-173. extremities. Brain Inj 2007;21:657-662. 16. Treib J, Haass A, Grauer MT: High-velocity 2. Halliday D, Resnick R, Walker J. bullet causing indirect trauma to the brain Fundamentals of Physics 8th ed. New York: and symptomatic epilepsy. Mil Med Wiley, New York; 2007. 1996;161(1):61-64. 3. Harvey EN, Korr IM, Oster G, et al. 17. Volgas DA, Stannard JP, Alonso JE. Secondary damage in wounding due to Ballistics: a primer for the surgeon. Injury, pressure changes accompanying the Int J Care Injured 2005; 36:373-379. passage of high velocity missiles. Surgery 18. Wang Q, Wang Z, Zhu P, Jiang J. Alterations 1946; 21:218-239. of the Myelin Basic Protein and 4. Livingstone WK, Davis EW, Livingstone KE. Ultrastructure in the Limbic System and the Delayed recovery in peripheral nerve lesions Early Stage of Trauma-Related Stress caused by high velocity wounding. J Disorder in Dogs. J Trauma 2004;56:604- Neurosurg 1945; 2: 170. 610. 5. MacPherson D. Bullet Penetration— Modeling the Dynamics and the About the Authors Incapacitation Resulting From Wound Trauma. El Segundo, CA: Ballistics Amy Courtney currently serves on the Physics Publications; 1994. faculty of the United States Military Academy at 6. Marshall EP, Sanow EJ. Street Stoppers: West Point. She earned a MS in Biomedical The Latest Handgun Stopping Power Street Engineering from Harvard University and a PhD Results. Boulder CO: Paladin Press; 1996 in Medical Engineering and Medical Physics from 7. Puckett WO, Grundfest H, McElroy WD, a joint Harvard/MIT program. She has published McMillen JH. Damage to peripheral nerves work in orthopedic biomechanics, biomedical by high velocity missiles without a direct hit. engineering, ballistics, acoustics, medical J Neurosurg 1946; 3: 294. physics, and traumatic brain injury. She has 8. Saxon M, Snyder HA, Washington HA, taught Anatomy and Physiology as well as Atypical Brown-Sequard syndrome following Physics. She has served as a research scientist gunshot wound to the face. J Oral Maxillofac at the Cleveland Clinic and Western Carolina Surg 1982;40:299-302. University, as well as on the Biomedical 9. Sturtevant B, Shock Wave Effects in Engineering faculty of The Ohio State University. Biomechanics, Sadhana, 23: 579-596, 1998. 10. Suneson A, Hansson HA, Seeman T. Michael Courtney earned a PhD in experimental Peripheral High-Energy Missile Hits Cause Physics from the Massachusetts Institute of Pressure Changes and Damage to the Technology. He has published work in Nervous System: Experimental Studies on theoretical astrophysics, theoretical and Pigs. J Trauma 1987; 27:782-789. experimental atomic physics, chaos, ballistics, 11. Suneson A, Hansson HA, Seeman T: acoustics, medical physics, and traumatic brain Central and Peripheral Nervous Damage injury. He has also served as the Director of the Following High-Energy Missile Wounds in Forensic Science Program at Western Carolina the Thigh. J Trauma 1988; 28:S197-S203. University and also been a Physics Professor, 12. Suneson A, Hansson HA, Seeman T. teaching Physics, Statistics, and Forensic Pressure Wave Injuries to the Nervous Science. Michael and his wife, Amy, founded the System Caused by High Energy Missile Ballistics Testing Group in 2001 to study Extremity Impact: Part I. Local and Distant incapacitation ballistics and the reconstruction of Effects on the Peripheral Nervous System. A shooting events. Light and Electron Microscopic Study on Pigs. J Trauma 1990;30:281-294. 13. Suneson A, Hansson HA, Seeman T. Pressure Wave Injuries to the Nervous System Caused by High Energy Missile