A system and method of providing therapy to a patient with electrodes extending along the longitudinal axes of large and small diameter nerve fibers. Electrical energy is delivered from a first electrode at an initial axial location, thereby evoking initial action potentials in the large and small fibers. The initial action potentials are allowed to be conducted along the large and small fibers in a first axial direction. Electrical energy is delivered from a second electrode at a second axial location at an instant in time when the initial action potential conducted along the large fiber has passed the second axial location and the initial action potential conducted along the small fiber is at the second axial location, thereby allowing a subsequent action potential to be evoked in the large fiber while preventing a subsequent action potential from being evoked in the small fiber.
