- pain associated with lumbo-sacral radiculopathy; patients with radiculopathy will only be included if they have pain radiating below the knee and have loss of small fibre function as indicated by quantitative sensory testing (elevation of at least one sensory modality threshold in the symptomatic limb - warm sensation > 9.6 0C and cool sensation > 5.6 0C - in L4, L5 or S1 dermatomes) [Quraishi, 2004].