Before we get into the types of injuries caused by lightning, we need to have a basis of understanding about what lightning is and how it works! Lightning is an electrical discharge caused by imbalances between storm clouds and the ground, or within the clouds themselves; most lightning occurs within the clouds. During a thunderstorm, an electrical gradient is formed by the interaction of moisture, warm air, and wind, and this current is eventually discharged as lightning. The exact science behind lightning has not been fully understood. However, a lot of hypotheses have been suggested (see this video).
Mechanism of Injury
- Direct Strike: It is all in the name, the patient is hit directly by the bolt of lightning. It most commonly occurs to people who are caught in the open. Although it is relatively rare (5% of lightning strikes), it is, however, the deadliest type of hit.
- Side Flash (Side Splash): The lightning directly strikes an object such as a tree or building, but the current flow jumps (splashes) from its original pathway onto the victim (path of the lowest resistance). It is the most common cause of lightning injury. Splashes may occur from person to person when several people are standing close together. It accounts for 30% of all lightning strikes.
- Conduction (Contact Injury): Contact exposure occurs when a person is holding on to or touching an object that is either directly hit or splashed by lightning. The current passes through the object on to the victim. It occurs in 15% of lightning strikes.
- Ground Current (ground strike): Ground current is produced when lightning strikes the ground or a nearby object and the current spreads through the soil. If a person has one foot closer to the strike, then a potential difference may exist between the two feet (see this video), and the current will pass up one leg and down the other leg. This is a common mechanism for several people being injured at the same time (it accounts for 50% of all lightning strikes).
- Upward Streamer Injury: An electrical streamer heads upward into the sky but does not reach sky lightning and thus does not complete a connection. The electrical charge passes over and through the involved individual, but it is not nearly as powerful as that of a direct strike that comes from the sky.
Although the current flow occurs over a concise period (1/10.000; 1/1000 seconds), the amount of current is significant. Injuries occur from a “short-circuiting” of several of the body’s electrical systems as well as the more direct trauma and indirect trauma due to muscular contraction and being thrown.
Respiratory System: Acute respiratory arrest due to the loss of respiratory drive leading to life-threatening hypoxia. Pulmonary contusion and hemorrhage can also occur.
Cardiovascular: The most common cause of death in a lightning strike victim is a cardiac arrest. After the lightning strike, simultaneous depolarization of all the myocardial cells results in asystole or ventricular fibrillation and thus asystole. However, due to automaticity, the heart soon begins to contract in an organised manner. If a concomitant respiratory arrest occurs due to a paralysis of the medullary respiratory center, the heart may deteriorate back into asystole secondary to the hypoxia. This respiratory arrest usually lasts longer than the cardiac arrest and is the major reason it is crucial to provide rescue breathing in lightning strike victims with cardiac arrest.
Other cardiovascular complications include direct myocardial damage or necrosis, coronary artery spasm, acute global cardiac dysfunction, atrial and ventricular dysrhythmias, pericardial effusion, ST-segment changes, as well as prolongation of the QT intervals.
Central Nervous System: When current traverses the brain, there can be coagulation necrosis of the brain, formation of epidural and subdural hematomas, intraventricular hemorrhage and paralysis of the respiratory center. Patients who suffer cranial burns are four times more likely to die than those without cranial burns. Direct cellular damage to the respiratory and cardiac centers in the fourth ventricle of the brain may occur, especially if current passes through the orifices of the head. Seizures may occur secondary to the initial hypoxia from respiratory arrest or due to intracranial damage. These are usually transient, although they may continue for the first few days. Confusion and anterograde amnesia are very common.
Neuro-psychological sequelae are very common: memory impairment, difficulty concentrating, sleep disturbances, personality change with increased lability and aggression.
Autonomic Nervous System (ANS): commonly, there is instability of the ANS for several hours after the injury. More severely injured patients may have lower extremity paralysis (keraunoparalysis) or in some cases, upper extremity paralysis.
Peripheral Nervous System: paralysis, pain, and paresthesias. Symptoms may be delayed by weeks to years. If present, the prognosis is poor for recovery.
Skin consequences of a lightning strike: Deep burns are unusual after lightning injury. At most, some deep partial-thickness burns may occur. There are four types of skin effects:
Ferning (see FIGURE 1): These are not actual burns, but an unusual pattern that occurs due to the electron shower. This skin finding is pathognomonic for lightning injury.
Linear burns: These are usually superficial and superficial-partial-thickness burns that occur from steam production from sweat or water on the victim due to the increased temperatures associated with the lightning strike.
Punctate Burns: These are multiple, closely spaced but discrete circular burns that individually range from a few millimeters to a centimeter in thickness. These resemble cigarette burns.
Thermal Burns: These are regular thermal burns that occur when a patient is wearing a metal object, such as a belt buckle or necklace, which heats up due to the electrical current travelling through it. There may also be thermal burns if clothing ignites.
Musculoskeletal System: Fractures and dislocations may occur due to intense muscular contraction or from being thrown. The significant muscular necrosis and extremity damage are seen in electrical injuries are unusual in lightning injuries.
In addition to flowing on the outside of the body (flash-over), this current may also enter the body through the cranial orifices (eyes, ears, nose, and mouth) and flow through the body. This may explain why some patients have specific injuries such as ocular and ear, and others do not.
Ocular: One-half of all lightning victims will have ocular injuries. Cataracts are the most common ocular injury. These may develop immediately or as late as two years after being struck. Transient bilateral blindness of unknown etiology is not uncommon. Dilated and nonreactive pupils cannot be used as a sign of death, as this may occur after lightning injury.
Ear: Temporary deafness can occur due to the excessive noise and shock wave. 30 to 50 per cent of victims will sustain rupture to one or both tympanic membranes. Disruption of the ossicles and mastoid bone can occur. Also, facial palsies are seen, due to direct nerve damage of the facial nerve as it runs through the auditory canal.
Treatment for First Responders
The first responder treatment should start with performing reverse triage and initiating CPR on those patients who are pulseless and apneic before caring for those who have spontaneous signs of life. Those with no spontaneous breathing or heartbeat may recover their heartbeat and will require assisted breathing until their respiratory drive returns. Breathing for these patients may prevent subsequent cardiac arrest due to hypoxia.
If a patient does not regain a pulse within 20 to 30 minutes, then one may discontinue the resuscitation. Initial steps follow, as always, MARCH (or ABCDE): Massive hemorrhage, Airway, Respiration, Circulation, and Hypothermia/hyperthermia. Call for evacuation to the closest medical facility. Stabilization such as splinting of fractures and spinal precautions should be performed as determined on your secondary assessment. The in-hospital treatment of lightning strike victims depends strongly on the injuries sustained and is varies hence between every victim; the treatment is, however, supportive in intent.