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7. Puckett WO, Grundfest H, McElroy WD, McMillen JH. Damageto peripheral nerves by high velocity missiles without a directhit. J Neurosurg 1946;3:294.8. Saxon M, Snyder HA, Washington HA. Atypical Brown—Sequardsyndrome following gunshot wound to the face. J Oral Max-illofac Surg 1982;40:299—302.9. Sturtevant B. Shock wave effects in biomechanics. Sadhana1998;23:579—96.10. Suneson A, Hansson HA, Seeman T. Peripheral high-energymissile hits cause pressure changes and damage to the ner-vous system: experimental studies on pigs. J Trauma1987;27:782—9.11. Suneson A, Hansson HA, Seeman T. Central and peripheralnervous damage following high-energy missile wounds in thethigh. J Trauma 1988;28:S197—203.12. Suneson A, Hansson HA, Seeman T. Pressure wave injuries tothe nervous system caused by high energy missile extremityimpact. Part I. Local and distant effects on the peripheralnervous system. A light and electron microscopic study onpigs. J Trauma 1990;30:281—94.13. Suneson A, Hansson HA, Seeman T. Pressure wave injuries tothe nervous system caused by high energy missile extremityimpact.PartII.Distanteffectsonthecentralnervoussystem.A light and electron microscopic study on pigs. J Trauma1990;30:295—306.14. Taylor RG, Gleave JRW. Incomplete spinal cord injuries. JBone Joint Surg Br 1957;B39:438—50.15. TikkaS, CederbergA,RokkanenP. Remoteeffectsofpressurewaves in missile trauma: the intra-abdominal pressurechanges in anaesthetized pigs wounded in one thigh. ActaChir Scand Suppl 1982;508:167—73.16. Treib J, Haass A, Grauer MT. High-velocity bullet causingindirect trauma to the brain and symptomatic epilepsy. MilMed 1996;161(1):61—4.17. Volgas DA, Stannard JP, Alonso JE. Ballistics: a primer for thesurgeon. Injury: Int J Care Injured 2005;36:373—9.18. Wang Q, Wang Z, Zhu P, Jiang J. Alterations of the myelinbasic protein and ultrastructure in the limbic system and theearly stage of trauma-related stress disorder in dogs. JTrauma 2004;56:604—10. Michael Courtney* Ballistics Testing Group,P.O. Box 24, West Point,NY 10996, United States Amy Courtney Department of Physics,United States Military Academy,West Point, NY 10996, United States *Corresponding author E-mail address:
[email protected](M. Courtney) doi:10.1016/j.injury.2008.03.020 AUTHOR’S REPLY VolgasD,StannardJ,AlonsoJ.Ballistics:Aprimerfor the surgeon [Injury 2005;36(3):373—9] Drs. Michael and Amy Courtney disagree with thestatement that ‘‘ It is not clear what effect thesewaves have on wounding characteristics of a pro- jectile, but it is likely that they play a small role in producing permanent injury .’’ They cite severalreferences to pig studies which demonstrate hightransient pressures at remote locations, and arguethat there are significant neurological injurieswhich occur in brain tissue as a result of distantwounding. While we do not disagree that thisoccurs, at the time of this article, only case reportsexisted which offered speculation that this was themechanism for injury in real-world casualties.Results in different animals may not have highcorrelation in humans due to differences in sizeandshape ofthebodycavitiesthroughwhichwavesmust propagate.If the assumption is that the high frequencywaves are transmitted as a hydrostatic wave, it islikely that the magnitude of the wave depends inpart on the compressibility of the tissue throughwhich it passes. Ballistic injuries to solid organs areoftenfatalandthereforetheclinicalsignificanceof remote injury is moot. Ballistic injuries to air-filledorgans are more survivable, but less likely to trans-mit fluid waves as effectively as solid organs. It isconceivable that transmission of fluid waves toremote sites occurs through the vasculature,thoughthis,toourknowledge,hasnotbeendemon-strated.Drs. Courtney may prove to be correct in theirbelief that remote effects of wounding are respon-sible for permanent damage in the brain or othervital organs, but this must be demonstrated in astudy of combat casualties.With respect to the drag formula, there areactually many versions of drag formulae. In prac-tice, drag is calculated by observation (radar) or bymaking general assumptions such as a constantballistics coefficient. In the real world, drag variesduring the flight of a round from the time it emergesfrom the barrel and stabilises to the time it reachesthe target. It is affected by wind as well, as thebullet yaws into the wind. These various factorsyield any formula purely theoretical. Nevertheless,Letters to the Editor 965 Drs. Courtney correctly provide one accepted dragequation.We applaud the efforts of Drs. Courtney in tryingto determine if the remote wounding by hydrostaticpressure is a major cause of injury and feel thatthis line of work should be continued with clinicalcorrelation from combat casualties. Conflict of interest None.David Volgas* Department of Surgery, University of Alabama atBirmingham, 510 Twentieth Avenue South,Faculty Office Tower #960, Birmingham, AL 35115, USA *Tel.: +1 205 975 0502; fax: +1 205 975 9532 E-mail address:
[email protected] doi:10.1016/j.injury.2008.03.021 966 Letters to the Editor
