By Melzack and Wall, in which ascending input from the posterior columns closes the gate on ascending spinothalamic tract fibers carrying pain sensations. Thus, patients effectively trade in sensations of pain for paresthesias, which themselves can often become unpleasant. A newer form of SCS known as high-frequency SCS operates at 10 kHz (known as HF10), avoiding the paresthesias that are perceptible at lower frequencies. To date, there have been no large studies providing head-to-head comparisons between HF10 and traditional SCS.