Molecular approaches for neuropathic pain treatment.

Neuropathic pain is initiated or caused by a primary lesion or dysfunction in the nervous system. It is estimated that 75-150 million people in the United States have a chronic pain disorder. Neuropathic pain has a great impact on the quality of life. It is debilitating and often has an associated degree of depression that contributes to decreasing human wellbeing. Moreover, the management of chronic pain is costly to the health care system. The United States Congress has declared the present decade (2001-2010) as the "Decade of Pain Control and Research", making pain a national healthcare priority. In Europe, statistics provided by the International Association on the Study of Pain (IASP) and the European Federation of the IASP Chapters (EFIC) indicate that one in five people suffer from moderate to severe chronic pain, and that one in three are unable or less able to maintain an independent lifestyle due to their pain. Between one-half and two-thirds of people with chronic pain are less able or unable to exercise, enjoy normal sleep, perform household chores, attend social activities, drive a car, walk or have sexual relations. The effect of pain means that one in four reports that relationships with family and friends are strained or broken, according to the IASP/EFIC data. Neuropathic pain treatment is extremely difficult. Neuropathic pain is a very complex disease, involving several molecular pathways. Excitatory or inhibitory pathways controlling neuropathic pain development show altered gene expression, caused by peripheral nerve injury. Current available drugs are usually not acting on the several mechanisms underlying the generation and propagation of pain. Nowadays, pain research is directing on new molecular methods, such as gene therapy, stem cell therapy and viral vectors for delivery of biologic antinociceptive molecules. These methods could provide a new therapeutic approach to neuropathic pain relief.