Functional pain

Neuropathic pain is defined as spontaneous pain and hypersensitivity to pain associated with damage to or pathologic changes in the peripheral nervous system as in painful diabetic peripheral neuropathy (DPN), acquired immunodeficiency syndrome (AIDS), polyneuropathy, post-herpetic neuralgia (PHN) or pain originating in the central nervous system (CNS), that which occurs with spinal cord injury, multiple sclerosis, and stroke. Functional pain, a relatively newer concept, is pain sensitivity due to an abnormal processing or function of the central nervous system in response to normal stimuli. Several conditions considered to have this abnormal sensitivity or hyperresponsiveness include fibromyalgia and irritable bowel syndrome. 

Neuropathic and functional pain is often described in terms of chronic pain. Neuropathic pain (e.g., postherpetic neuralgia, diabetic neuropathy) is a result of nerve damage, but functional pain (e.g., fibromyalgia, irritable bowel syndrome, tension-type headache) refers to abnormal operation of the nervous system. Pain circuits may rewire themselves and produce spontaneous nerve stimulation. 

Pain expression is also influenced by environmental factors, such as cultural attitudes, attention, and stress. Fibromyalgia (FM), tension headaches, and irritable bowel syndrome are a few of the functional pain conditions influenced by environmental factors. Environment may sometimes confound elTorts to isolate genetic contributions in clinical studies, and these elfects should be kept in mind. 

Clinically, GM-CSF or G-CSF have been used to accelerate recovery after chemotherapy and total body or extended field irradiation, situations that cause neutropenia and decreased platelets, and possibly lead to fatal septic infection or diffuse hemorrhage, respectively. G-CSF and GM-CSF reproducibly decrease the period of granulocytopenia, the number of infectious episodes, and the length of hospitalization in such patients (152), although it is not clear that dose escalation of the cytotoxic agent and increased cure rate can be rehably achieved. One aspect of the effects of G-CSF and GM-CSF is that these agents can activate mature cells to function more efficiently. This may, however, also lead to the production of cytokines, such as TNF- a, that have some toxic side effects. In general, both cytokines are reasonably well tolerated. The side effect profile of G-CSF is more favorable than that of GM-CSF. Medullary bone pain is the only common toxicity. 

Peripheral nervous system Nerve tissues lying outside the brain and spinal cord, functions include the transmittal of sensory information such as touch, heat, cold, and pain, and the motor impulses for limb movement. 

Morphine. This alkaloid exerts both a depressing and a stimulating action on the central nervous system, the depression affecting the brain especially the sensation of pain and the respiration the cerebral motoi functions are less affected. The stimulant action in the cord is best seen in the cold-blooded animals, when it may develop into tonic convulsions. In higher animals, but rarely in man, there may be some indication of this stimulant action. In cats it may also involve the motor areas, and they... 

Endogenous opioid peptide released both in the central nervous system and in other apparatuses of the body that have many regulatory functions, including inhibition of pain transmission. 

---