A transcutaneous electrical nerve stimulation apparatus having stimulus electrical pulses modulated in time and intensity to stimulate afferent nerves and cause the release of endogenous opiates which suppress pain. An astable pulse generator provides a first train of pulses at a selected repetition rate. A monostable pulse generator connected to receive the first train of pulses supplies a second pulse train having the frequency of the first train. The width of the pulses of the first train is varied over a predetermined range. A second monostable pulse generator connected to pulse amplifiers receives the first and second train of pulses and provides a supply pulse to the patient. Adjustable pulse modulators connected to the second pulse generators function to simultaneously increase the repetition rate of the first train of pulses and decrease the second train of pulses.
Method of improving sensory tolerance with modulated nerve stimulator