Researchers found that chronic neuropathic pain treatment may now be possible for diabetes, cancer and multiple sclerosis (MS). The findings were published in the Journal of Neuroscience and revealed the role of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which control pain transmission signals to a particular area of the brain.
Dr. Philippe Séguéla, Ph.D., lead study author, said, “We were able to show that reducing hyperexcitability of the ACC by blocking the HCN channels had analgesic effects — basically the feelings of pain were dramatically decreased. Our study has revealed one important mechanism linking chronic pain to abnormal activity of the ACC and it provides a cellular and molecular explanation for the overstimulation of neurons in the prefrontal cortex. This gives us new perspectives on therapeutic strategies that could target the HCN channels to help relieve chronic pain.”
Dr. Séguéla added, “The ACC has been shown to be a key centre to cognitive functions linked to memory and affective functions involved in feelings and emotions. We know that patients who suffer from chronic pain experience impairment of their working memory, difficulties focusing on certain tasks and may suffer from depression and anxiety. Our findings open new doors to research possible treatment of these debilitating symptoms that are linked to chronic pain.”
What is chronic neuropathic pain?
Neuropathic pain occurs when the sensory system becomes impacted through injury or illness. Nerves within this system cannot transmit sensations to the brain, which can lead to numbness or lack of sensation. In some cases of injury the individual experiences pain instead of a loss of sensation.
Neuropathic pain is not sudden nor does it finish quickly – it is chronic and persistent. Individuals who suffer from diabetes, some cancers and even multiple sclerosis may experience chronic neuropathic pain.
Factors that cause chronic neuropathic pain
Anything that contributes to the disruption of signals by the nerves can result in chronic neuropathic pain. Conditions such as carpal tunnel, diabetes, cancer, multiple sclerosis and shingles can all disrupt nerve signals.
Chronic pain in diabetes
Pain is a common symptom of diabetes affecting millions of patients. Chronic pain is defined as pain that is experienced for over six months. This pain may range from moderate to severe and may prevent daily tasks from being completed.
Pain from diabetes may occur from direct complications associated with diabetes or be a stand-alone condition. Chronic pain has been found to make managing diabetes much more difficult as it may limit a person’s ability to be physically active, which is known to better help manage diabetes.
Chronic pain from diabetes may result from a wound that has not healed or damage done directly to the nerves. If the pain is acute but lasts for too long, the brain will get tired of the constant signals and thus decide the injury is permanent.
There are factors that can make nerves more sensitive, thus contributing to more pain. Stress, fear, hopelessness and anger can all contribute to pain sensitivity. Chronic pain can also lead to vicious cycles, for example, people can become tense when they are in pain, which contributes to added pain. Furthermore, people may become inactive because they are in pain, but this simply leads to more stiffness and pain later on. Pain can also contribute to depression, which can increase pain sensitivity and lead to further depression, which leads to feeling more pain, and so on, and so on…
Chronic neuropathic pain in multiple sclerosis
Multiple sclerosis is a condition where the myelin – the protective layer around the nerves – becomes damaged by the body’s own immune system; MS is an autoimmune disease. The deterioration of the myelin can contribute to pain and even loss of movement in severe cases.
Measurements of pain in multiple sclerosis patients varies depending on questions asked to patients. Studies revealed that pain can be experienced by 44 to 80 percent of MS patients. Frequency of pain in MS patients, as well, can vary and is quite unclear. One thing is for certain: chronic pain in MS can cause difficulties with everyday tasks.
Further research is required to determine pain frequency in MS patients and find out how pain changes with the progression of the disease over time. Treatments also need to be evaluated to combat MS pain.
Exercise, cognitive behavioral therapy, biofeedback, heat and acupuncture have all been found to help assist pain associated with multiple sclerosis. Furthermore, these are safer methods to try for pain.
Chronic neuropathic pain in cancer
Chronic neuropathic pain in cancer is quite common as the pain is often associated with many cancer treatments. Chemotherapy-induced chronic neuropathic pain occurs in 90 percent of patients receiving the treatment. Although therapy is becoming more effective, side-effects associated with the treatments are becoming more and more problematic.
Another factor contributing to pain is that many cancer patients are seniors who have other conditions, which can worsen pain as well. This can also affect the type of treatment they receive.
Causes of chronic pain in cancer include:
- Bone metastasis – cancer which has traveled through the bones
- Peripheral neuropathy – injury to nerves, for example, caused by chemotherapy
- Radiation therapy and surgery
Opioids are commonly used in cancer patients to relieve pain, along with antidepressants, non-steroidal anti-inflammatory drugs (NSAIDs), gabapentin and topical anesthetics.
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