There is limited evidence that cancer pain or chronic pain from tissue damage as a result of a conditions (e.g. rheumatoid arthritis) is best treated with opioids. For neuropathic pain other drugs may be more effective than opioids, such as tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and anticonvulsants. Some atypical antipsychotics, such as olanzapine, may also be effective, but the evidence to support this is in very early stages. In women with chronic pain, hormonal medications such as oral contraceptive pills ("the pill") might be helpful. When there is no evidence of a single best fit, doctors may need to look for a treatment that works for the individual person. It is difficult for doctors to predict who will use opioids just for pain management and who will go on to develop an addiction. It is also challenging for doctors to know which patients ask for opioids because they are living with an opioid addiction. Withholding, interrupting or withdrawing opioid treatment in people who benefit from it can cause harm.Interventional pain management may be appropriate, including techniques such as trigger point injections, neurolytic blocks, and radiotherapy. While there is no high quality evidence to support ultrasound, it has been found to have a small effect on improving function in non-specific chronic low back pain.Psychological treatments, including cognitive behavioral therapy and acceptance and commitment therapy can be helpful for improving quality of life and reducing pain interference. Brief mindfulness-based treatment approaches have been used, but they are not yet recommended as a first-line treatment.
Peripheral neuropathic pain is often described as "burning", "tingling", "electrical", "stabbing", or "pins and needles". Causes
Pathophysiology
Under persistent activation, the transmission of pain signals to the dorsal horn may produce a pain wind-up phenomenon. This triggers changes that lower the threshold for pain signals to be transmitted. In addition, it may cause nonnociceptive nerve fibers to respond to, generate, and transmit pain signals. The type of nerve fibers that are believed to generate the pain signals are the C-fibers, since they have a slow conductivity and give rise to a painful sensation that persists over a long time. In chronic pain, this process is difficult to reverse or stop once established. In some cases, chronic pain can be caused by genetic factors which interfere with neuronal differentiation, leading to a permanently lowered threshold for pain.Chronic pain of different causes has been characterized as a disease that affects brain structure and function. MRI studies have shown abnormal anatomical and functional connectivity, even during rest involving areas related to the processing of pain. Also, persistent pain has been shown to cause grey matter loss, which is reversible once the pain has resolved.These structural changes can be explained by neuroplasticity. In the case of chronic pain, the somatotopic representation of the body is inappropriately reorganized following peripheral and central sensitization. This can cause allodynia or hyperalgesia. In individuals with chronic pain, EEGs showed altered brain activity, suggesting pain-induced neuroplastic changes.