Neuropathic pain is defined as the pain initiated or caused by a primary lesion, dysfunction, or transitory perturbation of peripheral or central nervous system. This is an older definition which has been later modified by International Association for the Study of Pain (IASP) as ''pain initiated by a lesion or disease of somatosensory system''. The disease or lesion can be located in the peripheral (e.g., diabetic neuropathy) or central nervous system (e.g., after spinal cord injury or stroke).