People with chronic pain often have been told it is “all in your head.” Now we can actually image brains with a combination of techniques and see actual differences in structure and chemistry that is being linked to chronic pain. The use of radioactive tracers, with PET, MRI and functional MRI scans are showing changing patterns of activity between normal people’s brains and those with chronic pain. The studies have led to several new key concepts, including glial cells and the role certain proteins play in pain expression.
Traditionally, pain has been related to signals of various nerves cell. Sensory nerve cells in the periphery of the body receive signals, then they are transmitted to the brain via the spine and interpreted by the brain, which transmits signals back to periphery. The electrical sensory and motor neurons are the critical components for understanding pain.
Now we are learning glial cells, which were thought of as structural components – the scaffolding of the nervous system – may be equally or more important in pain. Glial cells support and protect nerve cells. They also produce compounds that may control or contribute to chronic pain. As we identify the compounds, controlling their levels may be the next big discovery in managing chronic pain. One compound that is increased in chronic pain sufferers is the translocator protein. Studying the protein, one can see where glial cell activation has occurred. Using the special scans, the protein and glial cell activity can be measured, and hopefully in the near future, controlled.
Understanding the connection between pain, translocator proteins and glial cells is important to find effective treatments. Medications that may control chronic pain would decrease both translocator protein levels and glial activation. If a medication is working on these cells effectively, then the brain scans may change. As the science improves, hopefully we can use this knowledge to more fully identify the scope of problems with chronic pain and determine effective management strategies that actually work to reverse the changes and return the brain to healthier function.