In this study we compared the effect of temperature variation (> or = 32 degrees C to < or = 27 degrees C) on latency differences median to ulnar (ringdiff), median to radial (thumbdiff), palmar median to ulnar (palmdiff) and the sum of three, the combined sensory index (CSI), in 15 controls and 12 patients with carpal tunnel syndrome (CTS). After cooling, ringdiff was the most reliable techniq...