Emergency Medicine · Environmental Emergencies
The facts most likely to be tested
Cardiac arrest is the most common cause of immediate death following a lightning strike due to asystole or ventricular fibrillation.
Lichtenberg figures are pathognomonic ferning patterns on the skin caused by the superficial tracking of electrical discharge.
Keraunoparalysis is a transient, vasospastic-induced paralysis and sensory loss that typically resolves within hours of the injury.
Tympanic membrane rupture is the most common associated blunt trauma injury resulting from the blast effect of the lightning strike.
Cataracts are the most common long-term ophthalmologic complication and may develop months after the initial injury.
Reverse triage must be applied in mass casualty lightning incidents, prioritizing patients who are in cardiac or respiratory arrest over those who are conscious.
Rhabdomyolysis and myoglobinuria are significant risks following lightning strikes, necessitating aggressive fluid resuscitation to prevent acute kidney injury.
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A 24-year-old hiker is brought to the emergency department after being struck by lightning while seeking shelter under a tree. On arrival, he is conscious but complains of bilateral hearing loss and numbness in his lower extremities. Physical examination reveals a branching, fern-like erythematous pattern on his back and bilateral tympanic membrane perforations. His initial ECG shows sinus tachycardia, and his urine dipstick is positive for blood but negative for red blood cells on microscopy.
What is the most likely diagnosis for the skin findings, and what is the most appropriate next step in management?
Lichtenberg figures; aggressive intravenous fluid resuscitation.
The patient presents with pathognomonic Lichtenberg figures and signs of rhabdomyolysis (myoglobinuria), requiring aggressive fluids to prevent renal failure as per the high-yield management of lightning injuries.
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High yield triage
Etiology / Epidemiology
High-voltage direct current injury occurring in outdoor, open-field environments. Primary risk is cardiopulmonary arrest.
Clinical Manifestations
Lichtenberg figures are pathognomonic. Look for tympanic membrane rupture and cardiac arrhythmias.
Diagnosis
Clinical diagnosis. ECG is the gold standard for initial assessment of arrhythmias.
Treatment
Prioritize ACLS protocols. Do not delay resuscitation; treat the arrest first.
Prognosis
Survival depends on immediate CPR. Long-term neurological sequelae are common.
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Epidemiology & Etiology
Lightning strikes are most common in outdoor recreational activities or agricultural work. The injury is a high-voltage direct current event with extremely short duration. Unlike industrial electrical injuries, lightning causes a flashover effect where current travels over the skin rather than through the body.
Pertinent Anatomy
The tympanic membrane is highly susceptible to barotrauma from the shock wave. The myocardium is the most critical internal organ affected, often leading to immediate asystole or ventricular fibrillation.
Pathophysiology
The massive electrical discharge causes simultaneous depolarization of all myocardial cells, often resulting in transient asystole. The body's natural rhythm may recover, but respiratory arrest often persists due to brainstem paralysis. The intense heat causes superficial thermal burns and the characteristic Lichtenberg figures.
Clinical Manifestations
Patients often present with Lichtenberg figures, which are fern-like, erythematous skin markings. Cardiac arrest and respiratory paralysis are the most common causes of death. Check for tympanic membrane rupture and cataracts as classic associated findings. Neurological deficits, including Keraunoparalysis (transient lower extremity paralysis), are common.
Diagnosis
Diagnosis is primarily clinical based on history and physical exam. An ECG is the gold standard initial test to evaluate for QT prolongation or arrhythmias. Obtain cardiac enzymes if there is suspicion of myocardial injury.
Treatment
Initiate ACLS immediately, prioritizing ventilation as respiratory arrest often outlasts cardiac arrest. Do not delay resuscitation due to fear of electrical charge; patients do not hold a charge. Treat burns as standard thermal injuries. Monitor for rhabdomyolysis and acute kidney injury.
Prognosis
Prognosis is excellent if the patient survives the initial cardiopulmonary arrest. Long-term neuropsychiatric sequelae and cognitive impairment are the most frequent complications. Patients require long-term follow-up for delayed cataracts and neurological deficits.
Differential Diagnosis
High-voltage electrical injury: usually involves deep tissue necrosis and entry/exit wounds
Blast injury: presents with similar tympanic membrane rupture but lacks fern-like skin markings
Myocardial infarction: lacks the characteristic skin findings and history of lightning exposure
Seizure disorder: lacks the physical evidence of external electrical trauma
Hypothermia: lacks the specific cutaneous pathognomonic findings of lightning strikes