Sunday, August 24, 2008

Lightning Injuries

Lightning injuries include cardiac arrest, loss of consciousness, and temporary or permanent neurologic deficits; serious burns and internal tissue injury are rare. Diagnosis is clinical; evaluation requires ECG and cardiac monitoring. Treatment is supportive.
Lightning strikes cause about 50 to 75 deaths and several times more injuries annually in the US. Lightning tends to strike tall objects. It can strike a victim directly, or the current can be transferred to the victim through the ground or a nearby object. Lightning can also travel from outdoor power or electrical lines to indoor electrical equipment or telephone lines. The force may throw the victim several yards.
Although lightning current contains a large amount of energy, it flows for an extremely brief period (1/10,000 to 1/1000 sec). Thus, it rarely, if ever, causes serious cutaneous wounds and seldom causes rhabdomyolysis or serious internal tissue damage, unlike high-voltage and high-current electrical injury from manmade sources. Occasionally, patients have intracranial hemorrhage.
Symptoms and Signs
The electrical charge can affect the heart, causing asystole or other arrhythmias, or the brain, causing loss of consciousness, acute confusion, or amnesia.
Keraunoparalysis is paralysis and mottling, coldness, and pulselessness of the lower and sometimes upper extremities with motor and sensory deficits; the cause is sympathetic nervous system instability. Keraunoparalysis is common and usually resolves within several hours, although some degree of permanent paresis occasionally results. Other manifestations of lightning injury may include minor skin burns in a punctate or feathered, branched pattern, tympanic membrane perforation, and cataracts. Neurologic problems may include confusion, cognitive deficits, and peripheral neuropathy. Neuropsychologic problems (eg, sleep disturbances, anxiety) may occur. Cardiopulmonary arrest at the time of the strike is the most common cause of death. Cognitive deficits, pain syndromes, and sympathetic nervous system damage are the most common long-term sequelae.

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