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Once lightning strikes, metal will be incorporated into the pathway of the current. Andrews3 notes that cranial orifices are likely entry points for lightning current — with known consequences. The iPod merely assists a natural phenomenon.
Furthermore, skin impedance has a large capacitive component, and thus, there is zero impedance at the beginning of the passage of current. Charging of this capacitance leads to flashover, after which current will not re-enter the body (which is analogous to current behavior in wood4), and internal current will diminish monotonically.
A tree is not a safe shelter from lightning; National Lightning Safety Awareness Week promotes the concept that "no place outside is safe when thunderstorms are in the area" (www.lightningsafety.noaa.gov/week.htm). An iPod may prevent the user from hearing thunder, which is a primary warning of lightning danger. It is ironic that in our study of telephone-mediated lightning strikes,5 perforated eardrums that healed naturally performed better in the long term than those that were surgically corrected.
Chris Andrews, Ph.D., M.B., B.S.
Auscare Medical Centre
Indooroopilly 4068, Australia
Mary Ann Cooper, M.D.
University of Illinois
Chicago, IL 60612-7354
References
Electricity preferentially flows through tissues of high conductance. The temporal bone and air in the external auditory canals are highly resistant. The worst burns incurred from the iPod wires occurred away from the ear on the neck (Figure 1). If current had entered the body, it would have done so at the neck, not the ear.
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Underreporting and advances in imaging, rather than the effect of the iPod, probably explain why ossicular dislocations are not described in lightning strikes.
Paul T. Mick, M.D.
Patricia K. Lee, M.D.
Neil Longridge, M.D.
University of British Columbia
Vancouver, BC V5Z 1M9, Canada
Mick et al. comment that we did not consider that the headphone wires could have conducted electricity away from the patient's head. It is certainly a possibility; an additional possibility is that they conducted the current away from his heart, thus saving his life — we can only speculate about the pattern of injuries the patient would have received had he not been carrying an iPod. Although it is true that the patient did not lose consciousness, he had significant retrograde amnesia after the event, which is a recognized sequel of central nervous system injury in patients who have been struck by lightning.4 The additional fact that his mandible fractured in four places, at the same time dislocating both temporomandibular joints, leaves no doubt as to whether current passed through his head. We did not suggest that the otologic injuries were caused by electric shock, and we agree that blast effect was the underlying mechanism.
It is clear that the evolution of thin-collimation, multidetector computed tomography has facilitated the evaluation of the ossicular chain. However, the absence of previous reports of ossicular dislocation in patients who have been struck by lightning cannot simply be attributed to technological advances; there are numerous reports, spanning several decades, of surgical and postmortem middle-ear exploration in such patients but no previously documented case of ossicular disruption.5
A final note on jogging in thunderstorms: much of the very interesting debate that has followed the publication of this case report would perhaps be unnecessary if common sense were as ubiquitous as the iPod.
Eric J. Heffernan, M.B., B.Ch.
Peter L. Munk, M.D.
Luck J. Louis, M.D.
Vancouver General Hospital
Vancouver, BC V5Z 1M9, Canada
ejheffernan{at}eircom.net
References
i
I, Roje 
, Gluni V, Poljak K. Ear injuries caused by lightning: report of 18 cases. J Laryngol Otol 2001;115:4-8. [CrossRef][Web of Science][Medline]
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Related Letters:
Thunderstorms and iPods — Not a Good iDea
Heffernan E. J., Munk P. L., Louis L. J.
Extract |
Full Text |
PDF
N Engl J Med 2007;
357:198-199, Jul 12, 2007.
Correspondence
Thunderstorms and iPods — Two Reports of the Same Case
Heffernan E. J., Munk P. L., Louis L. J.
Extract |
Full Text |
PDF
N Engl J Med 2007;
357:723, Aug 16, 2007.
Correspondence
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