 Its well known that Spinal cord stimulation SCS changes the perception of chronic pain in the area stimulated by epidural electrodes. However, we dont know the effect of this type of stimulation on the perception of external sensations temperature, touch, pressure, and vibration and sharp pain. Quantitative sensory testing QST is used to quantify somatosensory phenotype. This QST battery tests different subtypes of nerve fibres Aβ, Aδ and C involved in the transduction of sensory information from the periphery to the spinal cord. 