The nervous system is particularly vulnerable to lightning injury, since resistance to current flow is lowest in nerve tissue. In addition to direct electrical trauma, CNS injuries may result from hypoxia secondary to cardiac arrest or to blunt trauma.10 The most lethal CNS injuries involve heat-induced coagulation of the cortex (as current passes through the brain parenchyma), formation of epidural or subdural hematomas, paralysis of the medullary respiratory centers, and intraventricular hemorrhage. When lightning victims present with coma, the differential diagnosis may include prolonged hypoxia, acute cerebral edema, closed head injury, ischemia, and hemorrhage, as well as other less obvious etiologies such as hypoglycemia, drug toxicity, and hypothermia ( Table 1.97-3). Autonomic dysfunction caused by the lightning strike may manifest as pupillary dilation, areflexia, anisocoria, or Horner's syndrome. These pupillary abnormalities are not related to CNS injury and have no relation to prognosis in comatose lightning-strike victims.
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