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Previous Volume 357:830-831 August 23, 2007 Number 8 Next

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To the Editor: Military blast exposure, principally in the form of roadside improvised explosive devices (IEDs), continues to be the signature mechanism of injury for coalition forces in Iraq.^1,2 In 2005, the U.S. military reported 10,953 IED attacks, at an average of 30 per day.³ Combat body armor provides soldiers with considerable protection against penetrating ballistic injury, yet it is unlikely to afford significant protection from the effects of blast overpressure. The ear is the organ that is most vulnerable to damage by blast overpressure.^2,4 Rupture of the tympanic membrane is a sentinel finding of blast exposure and occurs at a relatively low pressure differential.⁵ We analyzed the association between perforation of the tympanic membrane and loss of consciousness in a combat zone.

We attempted to conduct examinations during the early post-trauma period in all consecutive blast victims transported between October 1 and December 31, 2005, to the Air Force Theater Hospital (AFTH) at Balad Air Base in Iraq. The AFTH is a front-line, level 1 trauma hospital, representing the highest level of medical care available in Iraq. All examinations were conducted by one of five physicians (one neurosurgeon, one ear, nose, and throat or head and neck surgeon, and three emergency physicians). The study protocol was approved by the 60th Medical Group Institutional Review Board, which did not require written informed consent from patients, since the examinations were considered to be part of routine clinical care.

A total of 682 blast-injury victims of many nationalities were triaged and evacuated by helicopter from locations throughout Iraq. Of the 662 patients who survived initially, 541 (82%) underwent neuro-otologic examination. Our study used data from 210 male U.S. soldiers (mean age, 25.2 years) evaluated consecutively for both tympanic-membrane perforation and loss of consciousness (Table 1). The overall incidence of tympanic-membrane perforation was 35.2%; 37.8% of the perforations were bilateral. The overall incidence of loss of consciousness was 35.7%. There was a significant association between tympanic-membrane perforation and loss of consciousness (relative risk, 2.76; 95% confidence interval, 1.91 to 3.97). Approximately 37% of the soldiers reported wearing ear protection, a precaution that was associated with a significantly reduced risk of tympanic-membrane perforation but that did not modify the relationship between perforation and loss of consciousness.

View this table: [in this window] [in a new window]   Table 1. Association between Tympanic-Membrane Perforation and Loss of Consciousness among 210 U.S. Soldiers with Blast Exposure in Iraq, October–December 2005.

 
Our observation that there was a significant association between barotraumatic tympanic-membrane perforation and concussive brain injury suggests that physicians who are treating blast survivors with tympanic-membrane perforation need to have a high index of suspicion for concomitant neurologic injury.

The views expressed in this letter are those of the authors and do not necessarily reflect the official positions of the Departments of the Air Force and Defense.

Michael S. Xydakis, M.D., M.Sc., Lt.Col.
Vikhyat S. Bebarta, M.D., Maj.
Corey D. Harrison, M.D., Maj.
Jonathan C. Conner, M.D., Maj.
Gerald A. Grant, M.D., Lt.Col.
Air Force Theater Hospital
Balad Air Base, Iraq
michael.xydakis{at}us.af.mil

Anthony S. Robbins, M.D., Ph.D., Lt.Col.
David Grant Medical Center
Travis AFB, CA 94535

References

1. Xydakis MS, Fravell MD, Nasser KE, Casler JD. Analysis of battlefield head and neck injuries in Iraq and Afghanistan. Otolaryngol Head Neck Surg 2005;133:497-504. [CrossRef][ISI][Medline]
2. Gondusky JS, Reiter MP. Protecting military convoys in Iraq: an examination of battle injuries sustained by a mechanized battalion during Operation Iraqi Freedom II. Mil Med 2005;170:546-549. [ISI][Medline]
3. Iraq coalition casualty count. (Accessed August 2, 2007, at http://icasualties.org/oif/IED.aspx.)
4. Gutierrez de Ceballos JP, Turéquano Fuentes F, Perez Diaz D, Sanz Sanchez M, Martin Llorente C, Guerrero Sanz JE. Casualties treated at the closest hospital in the Madrid, March 11, terrorist bombings. Crit Care Med 2005;33:Suppl:S107-S112. [CrossRef][Medline]
5. Jensen JH, Bonding P. Experimental pressure induced rupture of the tympanic membrane in man. Acta Otolaryngol (Stockh) 1993;113:62-67. [Medline]

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This article has been cited by other articles:

• Myers, P. J., Henry, J. A., Zaugg, T. L. (2008). Considerations for Persons With Mild Traumatic Brain Injury. Perspectives on Audiology 4: 21-34 [Abstract] [Full Text]  
• Xydakis, M. S., Robbins, A. S., Grant, G. A., Das, R. R., Stonesifer, L. D., Ruff, R. L., Hoge, C. W., Engel, C. C., Castro, C. A. (2008). Mild traumatic brain injury in U.S. soldiers returning from Iraq.. NEJM 358: 2177-2178 [Full Text]