A 7th injury mechanism for lightning?

Lightning. Nature’s way of showing electric current, potential, and resistance. The average cloud to ground strike is 3 miles long, and carries 30,000 amps of current. The fact that people can be struck and live is amazing.

You may or may not know that there have been described 5 classic mechanisms of lightning strike injuries. These are:

1. Direct strike-lightning hits you
2. Contact voltage-lightning hits something you’re touching
3. Side splash-lightning hits something near you that you’re not touching, but some of the current “jumps” to you
4. Ground current-lightning hits something and the current travels through the ground to you
5. Upward streamer-as lightning comes down, electrical current travels up through you but does not complete the circuit. You still get hurt.

The National Weather Service has a page that shows all of these in hilarious graphical format. Of these, ground current accounts for about half, followed by side splash (~30%), then upward streamer (~20%). That’s so old school though, as the most recent of these was from 2002 (upward streamer). More recently, in 2012, barotrauma (primary blast injury) has been described as a 6th mechanism. I’ve discussed inner ear problems after lightning before, but barotrauma wasn’t defined as the primary cause of the injuries. I’m sure it plays a significant part. Also, there’s a case report of blast injury from lightning from as far back as 1984, strangely not cited by the more recent paper.

So what is the 7th mechanism? Secondary blast injury, of course. When lightning strikes something that can fragment, it sends shrapnel at high-speed, which can then impact victims and cause serious injuries. This article describes a case report of twins that were camping when an electrical transformer was struck some 15m away. Only one has any burn injury, but both suffer blast injuries from copper wire off the transformer. The twin who did not suffer the burn got the worst of the shrapnel, as a 2cm segment of wire penetrated the anterior chest. The only exterior wound is a minute puncture wound. Inside, however, it lacerated the lung, causing a hemopneumothorax, and lodged into the posterior chest. Removal required a thoracotomy, and thankfully the patient did well.

How this hasn’t been described in the keraunomedicine literature before escapes me. Certainly, not all strikes hit electrical transformers, but one of the authors of this paper has described blast injury from concrete after a strike that hit pavement. Logically, rocks could also cause shrapnel injuries if lightning strikes caused them to fragment. It’s pretty obvious that penetrating injury from lightning is rare, thus the paucity of reports. What we should take from this case report is the need to be aware that this is possible, and to treat lightning strike patients similar to gunshot patients. That is, examine extensively for wounds, and explore those wounds as needed, including imaging.

van Waes OJ, van de Woestijne PC, Halm JA. “Thunderstruck”: penetrating thoracic injury from lightning strike. Ann Emerg Med. 2014 Apr;63(4):457-9. [PMID 24054789]

Further Reading

• Blumenthal R, Jandrell IR, West NJ. Does a sixth mechanism exist to explain lightning injuries?: investigating a possible new injury mechanism to determine the cause of injuries related to close lightning flashes. Am J Forensic Med Pathol. 2012 Sep;33(3):222-6 [PMID 21952103]
• Moulson AM. Blast injury of the lungs due to lightning. Br Med J (Clin Res Ed). 1984 Nov 10;289(6454):1270-1. [PMC1443487]