Lightning and Lightning Injury

What is Lightning?

How Lightning Differs from Ordinary Electrical Injury

• Tintinalli's Emergency Medicine, Table 219-5

The Flashover Effect - Central to Understanding Lightning Injury

Types of Lightning Strikes (Mechanisms of Injury)

1. Direct strike - The lightning bolt makes direct contact with the victim. Accounts for about 5% of injuries but is most severe.
2. Side flash (splash injury) - Lightning strikes a nearby object (tree, pole, structure) and "jumps" through the air to the victim. Can injure multiple victims at once (e.g., a group sheltering under a tree). Side flashes may travel up to 30 meters.
3. Contact strike - The victim is touching an object (a telephone wire, metal fence, golf club) that is struck. Current transfers from the object through the person to the ground. Indoor phone use during a storm is a classic example.
4. Ground current (stride voltage / step potential) - Lightning hits the ground and spreads outward. If the victim's two feet are at different distances from the strike point, a voltage difference (potential difference) exists between them. Current enters one foot, travels up through the torso, and exits the other foot. This isolates neurovascular injury to the legs and is likely responsible for mass cattle deaths in open pastures during storms. Minimized by standing with feet together.
5. Upward streamer - A weak upward electrical streamer from the ground toward a storm cloud does not complete a full connection to the lightning channel, but still carries enough current to cause fatal injury. This is a recently recognized fifth mechanism.

Pathophysiology: How Lightning Causes Injury

1. Electrical Energy

2. Thermal Injury

• Lightning emits brief but intense thermal radiation, superheating surrounding air.
• Metal objects (belt buckles, jewelry, coins, zippers) are superheated and cause contact burns where they touch skin.
• Sweat and moisture on the skin can vaporize instantly, tearing clothing and causing superficial steam burns - sometimes mimicking signs of assault.
• Clothing can catch fire, causing secondary thermal burns.

3. Barotrauma

• Tympanic membrane perforation (very common; suspect in any lightning victim)
• Internal organ contusion
• The victim may be thrown violently, causing blunt trauma, fractures, and spinal injury.

4. Blunt Trauma

• Traumatic brain injury
• Fractures
• Spinal injuries

5. Optic/Acoustic Injury

• Intense photic (light) stimulation from the strike can damage the retina or later cause cataracts (especially in younger patients).
• Acoustic blast causes tympanic membrane rupture.

Skin: Lichtenberg Figures

Organ-System Effects

Cardiovascular

• Asystole is the initial rhythm most often.
• If the heart resumes, hypertension and tachycardia are common from sympathetic activation.
• ECG may show ST elevation, QT prolongation (which can persist for weeks), T-wave inversions.
• True myocardial infarction is rare; troponin and CK elevations usually reflect skeletal muscle damage.
• Atrial fibrillation and other dysrhythmias usually resolve spontaneously.
• Global myocardial contractility depression, coronary artery spasm, and pericardial effusion are reported.

Neurological - Keraunoparalysis

• Lower limb weakness greater than upper limb weakness
• Sensory abnormalities, pallor, coolness, absent pulses in the extremities
• Mimics acute arterial occlusion or spinal injury
• Usually resolves within an hour, though it can persist longer with amnesia and "neurotic" behavior clearing over days.
• Thought to result from excessive autonomic nervous system stimulation.
• Long-term sequelae include muscular weakness, photophobia, and neurological control disturbances.

Respiratory

• Central apnea from medullary stunning is the major immediate threat.
• May outlast cardiac standstill, making respiratory support the priority.

Renal

• Myoglobinuria and acute renal failure are uncommon (unlike high-voltage electrical injuries, where deep muscle destruction makes renal failure frequent).

Ocular

• Cataracts (sometimes delayed, appearing weeks later)
• Retinal damage
• Corneal injury

Auditory

• Tympanic membrane perforation
• Hearing loss

Key Clinical Points

• Survivors: 70-90% of lightning strike victims survive, but up to 75% of survivors have permanent sequelae.
• Reverse triage: At multi-victim scenes, treat the "apparently dead" first - they have the best chance of recovery with resuscitation.
• Prolonged CPR is justified: Full neurological recovery has been reported after victims were pulseless and apneic for up to 15 minutes. CPR lasting up to 8 hours has been successful. This may be explained by a lightning-induced state of "suspended animation" affecting all cells including the brain.
• Lightning kills approximately 20-50 people per year in the United States, with about 500 injuries annually.