Lightning-strike injuries are fascinating and unpredictable natural phenomena with potentially devastating effects. It is estimated that worldwide there are 1800 active thunderstorms at any given moment, with up to 44,000 thunderstorms producing 8 million lightning flashes per day.1
Lightning can be considered a form of high-voltage direct current. It is a transfer of an electrical charge between polarized positive and negative charges within a storm cloud and the ground. It results from an elevated electric potential difference between the excess of negative charges at the bottoms of thunderclouds that repel freely moving electrons at the underlying surface on the ground, thus positively charging it by induction. The lightning discharge eventually occurs when the electrical resistance of air is exceeded.2 The physical processes that take place in and around a thundercloud generate static electricity between individual water droplets/ice particles that collectively, at a considerable scale, involve prominent surfaces/structures on the ground below so as to create a massive electrical circuit. Before the actual bolt, the electrons from the cloud follow a zigzag path toward the ground branching at various locations. This is known as a stepped leader, by which the charges present on the earth's surface are attracted upward forming a so-called streamer: their encounter occurs at approximately 150 to 200 m above the ground. The flow of electrons occurs at 50-ms intervals, via the route of lowest electrical resistance, in a sort of ionized channel whose diameter varies from a few millimeters to 20 cm. Due to the extreme speed of the phenomenon, it appears continuous to the human eye, unable to appreciate separate flashes of light at rates faster than a tenth of a second. Between clouds of different potential, an electrical discharge can occur, commonly called a lightning flash. The physical characteristics of lightning are: a spatial discharge length that varies from 8 to 10 k, an average discharge diameter of 20 cm, an electrical potential of several million Volts, an intensity that oscillates between 10,000 and 110,000 A, and a temperature equal to 8000°C.3 The injury produced to the victim struck by lightning principally derives from electrothermal phenomena, though indirect mechanical effects are not trivial. The majority of deaths caused by lightning strikes are due to cardiac arrest and/or electrothermal injuries. Most cases occur outdoors; nevertheless, some cases do occur indoors.
Herein, the authors report the case of a lightning-strike injury of a previously healthy middle-aged man fatally struck while working indoors in a cottage.
A 53-year-old man was renovating his cottage, working alone. In the evening, after receiving no answer from him, the family resorted to calling the police. Upon their arrival, with the forensic pathologist, the man was lying on his right side between 2 metallic sawhorses. Tetany was ascertained inasmuch as during the investigation of the scene, which took place roughly 2 hours after the incident, the corpse revealed an unusual rigidity, which could not be overcome by manual force, thus inexplicable by rigor mortis alone. The surroundings gave no indication that any fire had started. His tools were scattered about, and the furnishings present in the room showed no signs of burns. However, firefighters found no damage to the circuit breaker or any detectable electrical malfunction. The structure of the cottage consisted in a rudimentary system of walls with steel beams connecting the exterior of the structure to the central portion of the cottage through the roof. The beams may have played an essential role in conducting electrical current during the storm. The metal tools in the room, directed toward the ceiling, may have further facilitated the current (Fig. 1).
The engineer that examined the scene suggested that lightning had entered the cottage through the beams and created an arc at the spot where the victim was working.
The meteorological office reported that a thunderstorm had occurred in the area a few hours before the incident. Moreover, another person was also struck by lightning while crossing a bridge in the same village.
Careful medical-legal and engineering evaluations make it possible to establish that the lightning reached the metal beams, placed within the walls although protruding to the exterior. The electrical current discharging from the bottom upwards formed an electric arc. The victim, who was close to metallic objects (ie, sawhorses), was struck on the left foot, and the current exited from the right hand passing through the heart (Fig. 2).
Clothing and Autopsy Findings
The autopsy showed the corpse of a man (175 cm in height, weighing 75 kg) with multiple signs of lightning-strike injury. The body was covered by burnt remnants of clothing. External examination revealed burnt shoes, particularly the sole of the left shoe, thought to be the entrance site. First-degree, second-degree, and third-degree burns were present in the abdominal region, proximal thighs, and genitalia, comprising approximately 70% of the whole body surface area. The beard, body hairs, and scalp were singed with unaffected areas of skin. Lichtenberg striae were present on the left thigh. Macroscopically, the right thumb showed deepithelialization and yellowish-ochre discoloration. The tongue was oedematous, and the papillae were scorched. Internal examination revealed congestion of all the major organs with edema of the lungs. Moreover, autopsy showed the absence of soot in the trachea and diffuse muscle tetany. Blood tests revealed a low level of carboxyhemoglobin (3.9%).
Toxicological analysis excluded the presence of alcohol, amphetamine-methamphetamine, 3,4-methylenedioxy-methamphetamine, tetrahydrocannabinol, cocaine, opiates, methadone, barbiturates, benzodiazepines, neuroleptics, and tricyclic antidepressants.
Histological examination revealed myocardial contraction band necrosis, fragmentation, and cellular disorder. Moreover, this analysis showed an acute pulmonary emphysema and edema. On the right thumb, lightning-strike injury produced epidermal necrosis, scabs, and blisters, with homogenization of the superficial and deep dermis (Fig. 3).
According to the autoptic and histological findings, the cause of death was determined to be by acute ventricular failure secondary to atmospheric electricity (lightning) with contextual skin burns.
Lightning strikes the Earth in excess of 100 times per second, that is, 8 million times a day.4 In the United States, this phenomenon causes approximately 300 accidents and 100 deaths per year.5 The National Weather Service of the United States currently estimates 70 deaths/year, and a mortality rate of 10%. Furthermore, city dwellers are thought to be at less risk than those in rural areas.6 With very few exceptions, individuals were struck by lightning while engaged in outdoor activities. People working on construction sites or in agriculture, as well as those who play golf or go fishing, swimming, or camping are particularly at risk. Fatal lightning strikes are more common in the summer and autumn, between May and September, more often in the early afternoon and evening.7
Lightning strikes produce a mortality rate of 10% to 30% with a 76% risk of long-term consequences in survivors.8 The contact period of lightning with the victim is approximately a 10,000th to a 1000th of a second.
Lightning may cause injury via a diversity of mechanisms: direct strike, “side flash,” wherein the lightning strikes another object and then “jumps” onto the victim, or by conduction through another object.2
In some cases, a phenomenon called flashover can occur, in which part of the discharge is diverted to the surface of the body because attracted by metallic conductors and body moisture. Several authors9 believe that this is a protective phenomenon because it allows the current to flow along the surface of the body, instead of through it.
In several studies, death by lightning strike occurs immediately10 due to cardiac asystole or ventricular fibrillation.11,12 The electrical current causes a “countershock” which simultaneously depolarizes all myocardial cells. Histological examination reveals a mixture of necrosis, hemorrhage, eosinophilic myocarditis,13,14 and possible cardiac disarray. At the same time, respiratory arrest can be caused by muscle paralysis and respiratory center depression. Aspiration pneumonia, pulmonary edema, and diffuse alveolar hemorrhage can also occur. These findings may result from diffuse central nervous system depolarizations, which leads to a faulty regulation of the gag reflex, or from resuscitation attempts.4,15 Lightning-strike injury can also trigger an intense catecholamine release, with ensuing myocardial contraction band necrosis.
A typical skin lesion of lightning-strike injuries is the “arborescent” pattern, resembling a fern or tree-like pattern of pink skin discoloration, representing intravascular hemolysis within subcutaneous blood vessels.2 Histologically, it is characterized by intact epidermis and focal blood extravasation in subcutaneous fat.16 In addition, the lightning strike may also cause carbonization of skin (more pronounced at entry and exit sites) and epidermal necrosis, whereas symmetrical macular marks underneath breasts are rare.17
Another frequently reported autopsy finding is ruptured tympanic membranes, identified in 50% to 80% of the victims.15,18
In the event of lightning striking a house, the postulated mechanism of injury consists in the electrical energy being conducted by way of any type of pipes or wiring.19
The majority of cases of indoor lightning-strike injuries are related to the use of the telephone.20,21 In such cases, the lightning incident victim received either an electrical or an acoustic shock while on the phone. It is not rare for the victim to be “thrown to the ground” presumably by violent muscle contractions upon the electric shock. These events almost never cause death because the individual receives only a fraction of the lightning current or a low-intensity current.
Bianco-Pampin et al22 describe a case of an indoor lightning strike, in a 55-year-old man, reached by lightning discharge while in bed. In this unusual case, investigation of the scene and autopsy were crucial in establishing the cause of death.
Kreci et al23 report a case of a 46-year-old man who died inside his kitchen due to the electrical discharges conducted through his chimney, whose the external portion was struck by lightning.
A review of the literature confirmed the extreme rarity of the case proposed. Proper interpretation of the data from autopsy and histological analysis led to an accurate reconstruction of the events causing death.
From a post-mortem and medical-legal standpoint there are different elements which support the conclusions that the death was caused by the effects of a lightning strike. Carbonization of the shoes indicated the entry site of electrical discharge to the body. The lightning strike determined diffuse muscle tetany and the presence of cutaneous burns of various degrees secondary to the Joule effect. The low concentration of carboxyhemoglobin in the blood and the absence of soot in the bronchial tree indicated that death was abrupt, preceding the onset of the burns. Finally, epidermal necrosis, with homogenization of the surface dermis of the right hand showed the passage of current within the skin, which represented the exit site of the electrical current.
In summary, investigation of the scene and autopsy findings proved crucial in determining the cause of death.
The case at hand appears of particular medical-legal interest, due to the extremely rare circumstances under which the indoor lightning strike occurred and to the interpretative difficulties during investigation of the scene. In fact, the corpse was carbonized in the absence of evident sources of heat or of flames inside the cottage. The initial hypotheses of the investigators also considered the possibility that the subject might have been set aflame elsewhere, then concealed in the cottage. This notion was later rejected after careful analysis of the corpse during post-mortem examinations in relation to the relevant environmental data. Consequently, in addition to the rare nature of this fatality, the case illustrated serves as a warning to forensic pathologists. It underscores that correct interpretation of the data uncovered at the scene of investigation as well as through autoptic and histological examinations are of the utmost importance for precisely determining cause and manner of death.
The authors would like to thank F. Portunato and M. Botto for their assistance in collecting circumstantial data.
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