These are usually caused by the passage through the body of an electric current of high voltage owing to accidental contact with a live wire or to a discharge of lightning. The general effects produced are included under the term electric shock, but vary greatly in degree. The local effects include spasmodic contraction of muscles, fracture of bones, and in severe cases destruction of tissues which may amount simply to burns of the skin or may include necrosis of masses of muscle and internal organs. Fright due to the unexpectedness of the shock, and pain due to the sudden cramp of muscles, are the most common symptoms and in most cases pass off within a few minutes. In more severe cases — especially when the person has remained in contact with a live wire for some time, or has been unable to let go of the electrical contact owing to spasmodic contraction of the muscles — the effects are more pronounced and may include concussion or compression of the brain. In still more severe cases, death may ensue either from paralysis of the respiration or stoppage of the heart’s action. If prompt measures are taken for treatment, the victim can often be resuscitated.