This invention provides a new technology for management of back pain by stimulating the spinal cord in a manner that renders it refractory to transmission of deleterious or undesirable sensory input. The electrical stimulus comprises high frequency pulses in a regular or complex pattern or that are stochastically produced under microprocessor control. The stimulus is applied directly to the surface of the spinal cord from within the spinal canal, which provides important benefits over previous technology. The stimulus alleviates symptoms and signs of back pain, while minimizing the risk of side effects such as paresthesia, and potentially minimizing the effects on motor neuron transmission and proprioception.