Category Archives: lightning

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.
original data: Sebastien D'ARCO, animate: Koba-chan
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.

“Thunderstruck”: Penetrating Thoracic Injury From Lightning Strike.
http://www.ncbi.nlm.nih.gov/pubmed/24054789

What? I can’t hear you!

Lightning strikes cause an average of 53 deaths per year in the US, killing about 10% of those who are struck. Strikes are well known to cause audiovestibular sequelae. The first reported case of deafness after lightning was in 1879, and the most common cause of deafness is tympanic membrane rupture. However, both sensorineural hearing loss and conductive hearing loss have been described as well.  Vertigo has also occurred after lightning strikes.

This article reviewed 15 studies to help describe ear damage caused by lightning. After describing the reported injuries, the authors then attempt to identify the root cause of the injuries.  These are varied, and range from electrical conductance, to primary blast, to hypoxia, to anatomical disruption, to stress response, to vascular effects.  They end by simply stating that the pathophysiology is “an unsolved conundrum.”

They recommend a management protocol for these injuries. It begins with otologic, vestibular, and neurologic assessments. They do recommend against early surgical repair for TM injuries. Psychiatric assessment is advised to help prevent and treat PTSD and persistent neurobehavioral disorder.  The last recommendation is followup at 1 year to evaluate for delayed sequelae.

The article is worth it simply because it gives a logical treatment plan for the patient with inner ear problems after being struck by lightning.

Inner ear damage following electric current and lightning injury: a literature review
http://www.ncbi.nlm.nih.gov/pubmed/23649510