Keraunomedicine is the medical study of lightning

Lightning

Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

 casualties. The term may have been coined by Chris Andrews, a lightning and electrical injury researcher. Lightning injuries

Injury

-By cause:*Traumatic injury, a body wound or shock produced by sudden physical injury, as from violence or accident*Other injuries from external physical causes, such as radiation injury, burn injury or frostbite*Injury from infection...

 result from three factors: electrical damage, intense heat, and the mechanical energy which these generate. While sudden death is common because of the huge voltage of a lightning strike, survivors often fare better than victims of other electrical injuries caused by a more prolonged application of lesser voltage.

Path to victim

Lightning can strike or injure humans in four different ways:

• Direct strike
• 'Splash' from nearby objects struck
• Ground strike near victim causing a difference of potential in the ground itself (due to resistance to current in the Earth), amounting to several thousand volts per foot, depending upon the composition of the earth that makes up the ground at that location (sand being a fair insulator and wet, salty and spongy earth being more conductive).
• EMP
  Electromagnetic pulse
  An electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...
  
   or electromagnetic pulse from close strikes - especially during positive lightning discharges

In a direct hit, the electrical charge strikes the victim first.
Splash hits occur when lightning jumps to a victim (lower resistance path) from a nearby object that has more resistance, striking the victim on its way to the ground.
In ground strikes, the bolt lands near the victim and is conducted by a connection to the ground (usually the feet), due to the voltage gradient in the earth. This can still cause substantial injury.

Heat

A bolt of lightning can reach temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

s approaching 28,000 degrees Celsius (50,000 degrees Fahrenheit) in a split second. This is about five times hotter than the surface of the sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

. There is sometimes spectacular and unconventional lightning damage. Hot lightning (high-current lightning) which lasts for more than a second can deposit immense energy, melting or carbonizing

Carbonization

Carbonization or carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal...

 large objects. One such example is the destruction of the basement insulator

Electrical insulation

thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...

 of the 250-metre-high central mast of the Orlunda radio transmitter, which led to its collapse. The intense heat generated by a lightning strike can burn tissue, and cause lung damage, and the chest can be damaged by the mechanical force of rapidly expanding heated air.

Electricity

Counterintuitively, if the victim's skin resistance

Electrical resistance

The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

 is high enough, much of the current will flash around the skin or clothing to the ground in a direct strike, resulting in a surprisingly benign outcome.

The lightning often leaves skin burns in characteristic Lichtenberg figure

Lichtenberg figure

Lichtenberg figures are branching electric discharges that sometimes appear on the surface or the interior of insulating materials. They are named after the German physicist Georg Christoph Lichtenberg, who originally discovered and studied them...

s, sometimes called lightning flowers; they may persist for hours or days, and are a useful indicator for medical examiners when trying to determine the cause of death. They are thought to be caused by the rupture of small capillaries under the skin, either from the current or from the shock wave

Shock wave

A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

. The intense electrical energy can cause a loss of consciousness; it is also speculated that the EMP

Electromagnetic pulse

An electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...

 created by a nearby lightning strike can cause cardiac arrest

Cardiac arrest

Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

.

Concussive injury

Just as heat can cause expanding air in the lungs, the atmospheric expansion by lightning (the cause of "thunder") can cause concussive and auditory injury at extremely close range. Other physical injury can be caused by objects damaged or thrown by the lightning strike.

Immediate

The most critical injuries are to the circulatory system

Circulatory system

The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

, the lung

Lung

The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

s, and the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

 but injuries also occur to other body systems. Some victims suffer immediate cardiac arrest

Cardiac arrest

Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

 and will not survive without prompt emergency care, which is safe to administer because the victim will not retain any electrical charge after the lightning has struck (of course, the rescuer could be struck by a separate bolt of lightning). Others incur myocardial infarction

Myocardial infarction

Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

 and various cardiac arrhythmias, either of which can be rapidly fatal as well. Loss of consciousness is very common immediately after a strike. Amnesia

Amnesia

Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...

 and confusion

ConFusion

ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association. Commonly, it is held the third weekend of January. It is the oldest science fiction convention in Michigan, a regional, general SF con...

 of varying duration often result as well.

Experiments on sheep show that a lightning strike to the head of a victim enter through the eyes, ears, nose and mouth, converging at the brainstem, which controls breathing. Many unconscious victims, who appear lifeless, die of suffocation. Chances of survival may be increased if artificial resuscitation is started immediately and continued until the brainstem recovers.

Long-term

A complete physical examination by paramedic

Paramedic

A paramedic is a healthcare professional that works in emergency medical situations. Paramedics provide advanced levels of care for medical emergencies and trauma. The majority of paramedics are based in the field in ambulances, emergency response vehicles, or in specialist mobile units such as...

s or physician

Physician

A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...

s may reveal ruptured eardrum

Eardrum

The eardrum, or tympanic membrane, is a thin membrane that separates the external ear from the middle ear in humans and other tetrapods. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...

s, and ocular cataract

Cataract

A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...

s may develop, sometimes more than a year after an otherwise uneventful recovery. Long-term injuries are usually neurological in nature, including memory deficit, sleep disturbance, chronic pain, and chronic dizziness.

External links

• Medical Aspects of Lightning at NOAA's Lightning Safety pages
• Lightning Strike & Electric Shock Survivors International, Inc.
• Kids' Lightning Information And Safety – Written entirely by a young lightning strike survivor, with information & resources
• Struckbylightning.org, Inc. – A non-profit org using rich media resources and information
• The National Lightning Safety Institute (NLSI) – Reports and statistical information
• National Oceanic and Atmospheric Administration – Bibliography on Medical Effects of Lightning Strikes
• Lightning Strike Survivor's Resources On The Web (archived)