The Lichtenberg figure on the arm of a 10-year-old girl struck by lightning at the window of her home in Merthyr Tydfilsouth Wales in May 2011.
Source: BBC News
Lightning effects on the human body: immediate and short-term
Although lightning is a potentially lethal high-voltage electric current, it has contact with a person for only milliseconds unlike the longer lasting and continuous current experienced if someone touches a bare wire of an indoor electrical circuit or an outdoor power cable.
The short-lived electric current of a lightning strike may simply pass over the surface of a person's skin or clothes without most of it penetrating the body. This 'flashover effect' explains why some people experience minor injuries only. Indeed, often and contrary to popular belief, many people who experience a lightning strike suffer no burns.
For further information, refer to the extensive review of 'lightning injuries' by Professor Mary Ann Cooper, Christopher J. Andrews and Ronald L. Holle, a chapter in Paul C. Auerbach (ed.), Wilderness Medicine, 2007, 5th edition.
Unfortunately, there are occasions when a large amount of the current penetrates the skin causing serious burns and major damage to internal organs such as the heart, lungs and brain, which may lead to cardiopulmonary arrest and death. Only cardiac and respiratory arrest causes immediate death, not burns.
When someone is struck, the electrical current may follow a line of sweat, as a moist skin surface is a better conductor than adjacent dry areas of skin. The heat generated by the current may cause this moisture to superheat and vapourise (turning to steam), causing minor or superficial burns to the sweaty parts of the body. If such sudden explosive vapourisation takes place on sweaty feet in the confined space of tight-fitting footwear then socks may be ripped and footwear torn apart.
The eyes are especially sensitive to electric currents and heat so can be damaged if a person is struck by lightning or suffers the effects of a close lightning strike. Cataracts may develop many months or even a year or so later.
Being close to a lightning strike is like being near to an explosion. Ear drums may be ruptured. The shock or pressure wave can throw people to the ground causing blunt trauma injuries and even loss of consciousness for a while. Within 10 to 20 metres of a strike, the electric current spreading out from the strike point may pass up one leg and down the other, causing the leg muscles to involuntary contract and throwing that person violently to the ground. Temporary paralysis of the legs and sometimes the arms may occur which may take several hours to wear off. People struck may be disoriented and confused for several hours.
Flashover effects may leave to reddish fern-like pattern on the skin called a Lichtenberg figure, named after a scientist who first described the pattern. It is caused by electrons being driven into the epidermis which radiate outward from successive points in a fractal pattern of repeated bifurcations. Not everyone struck by lightning has this pattern. It doesn't appear until half an hour or several hours after the lightning strike and disappears within a few hours to 48 hours. It is not a burn and leaves no lasting effects but it is a tell-tale sign that the person was struck by lightning.
Lightning effects on the human body: long-term or permanent
Some people who survive a lightning strike may suffer long-term or even permanent health problems. These may be wide-ranging from sleep, concentration and memory problems, post-traumatic stress disorder (PTSD), depression, irritability, eye damage and cataracts, and chronic pain. In rare and extreme cases, damage to the brain may be so severe that they need round-the-clock medical care.
Some people who experience long-term problems as a result of a lightning strike may not have suffered any serious injuries at the time of the strike. Only days, weeks or months later have behavioural and psychological problems developed.
The Lightning Strike and Electric Shock Survivors International (LS&ESSI)
in the US is a non-profit support group run by, and for, survivors and their families from across the world.