Neuropathology of lightning-strike injuries

When a person is struck by lightning a spectrum of neurologic damage can result. Approximately one third of the strikes prove to be fatal. The possibility of damage to the CNS relates to the type of lightning injury (direct strike, stride potential, or side flash), the intensity and duration of the current, the pathway of the current within the body, and secondary injuries to brain either from cardiac arrest and hypoxia or from physical trauma. Direct strikes to the head have a high degree of fatality and often result in petechiae or larger brain hemorrhages. Although there may be some predilection for the petechiae to occur in the brainstem, the larger hemorrhages may be particularly located near the pathway of the electrical current and result from direct damage to brain vasculature. Enlarged perivascular spaces seen histologically are relatively subtle; they have been attributed to the effects of gas bubbles from electrolysis, heat formation, or both. Small vessel thrombi and neuronal changes may be present nearby. Some brain tissue softening and edema may be direct effects of passage of current. Often, however, hypoxic encephalopathy and cerebral edema occur following cardiopulmonary arrest when the passage of the current through the body presumably generates cardiac arrhythmias. Considerably less is known about the spinal cord injuries in lightning strike, although one detailed recent study suggests that demyelination may be an underlying mechanism. Similarly, myelin damage appears to be a feature of electrical and possibly lightning injury to the peripheral nervous system.