An implantable microstimulator includes an elongate casing, a flap coupled directly to the casing, and electrodes attached to the flap such that the electrodes extend laterally relative to the longitudinal axis of the casing. The electrodes are coupled to active circuitry that is housed within the casing. Due to the lateral arrangement of the electrodes relative to the casing, effective operation of the microstimulator may still occur even after the microstimulator migrates away from the target stimulation site. Since there are not any leads associated with the microstimulator, the entire microstimulator, including the electrodes and the casing, is implanted adjacent to the target stimulation site. The electrodes may be configured for mono-polar or multi-polar stimulation. In one example, the microstimulator includes an insulative coating on the casing and the coating and the flap are contiguous.
