The first recorded application of the use of electricity to treat human aliments was in ancient Rome. Anthero, a freed slave, was walking in the surf when he stepped on an electrically charged torpedo fish, shocked himself and was allegedly cured of gout (1). Electric stimulation therapy is the use of electrical currents in the treatment of disease and injury. This category includes a variety of electrical currents to include high voltage galvanic, interferential, Russian stimulation, transcutaneous nerve stimulation and micro-current, etc.
(1) Cambridge NA. Electrical apparatus used in medicine before 1900. Proc R Soc Med 1977 Sep;70(9):635-41.