Presented by: Sean Mackey, MD, PhD
Chief, Division of Pain Medicine
Associate Professor, Anesthesia
Stanford University Medical Center
- Fibromyalgia is a chronic condition with no known cause that appears to increase the brain’s susceptibility to pain
- It appears to affect certain neurotransmitters in the brain, overactivating its pain receptors
- The condition is complicated by other physical and psychological factors, including sleep disorders and fatigue, that may overlap with other diseases
- It can be managed with a range of medications as well as behavior modification and mind-body strategies
The pain that comes from hitting a finger with a hammer, pulling a muscle, suffering from a toothache, or taking an unexpected fall serves an important purpose, warning our bodies to respond to danger. But for 2 to 5 percent of adult Americans, particularly women, the pain never seems to go away.
Fibromyalgia is a chronic condition characterized by widespread pain in the muscles, ligaments, and tendons, as well as increased sensitivity and tenderness. There is no known cause, although researchers believe it stems from a genetic predisposition or environmental trigger that increases the brain’s susceptibility to pain signals. People with fibromyalgia may have a lower threshold for pain because certain chemicals in the central nervous system (the brain and spinal cord) are overproduced, keeping the brain in a state of heightened sensitivity.
“Fibromyalgia is difficult to diagnose because it’s the result of a neural disruption rather than a physical injury, The central nervous system is amplifying signals: what healthy people interpret as touch or pressure, patients with fibromyalgia perceive as pain,” said Sean Mackey, MD, PhD, an associate professor of anesthesiology and the director of Stanford’s Division of Pain Management, who discussed his work at a Stanford Health Library presentation on October 2. “It’s difficult to treat because even though we can prescribe medication to control the pain, we often don’t have a real cure. Our goal is to address all aspects of the condition and help give people back autonomy and control of their life.”
The condition is further complicated by the subjective nature of pain. Mackey described pain as “an unpleasant sensory or emotional experience,” which makes it both elusive and difficult to measure.
“Often there is no real link between the physical damage and the individual’s experience of pain,” he said. “Pain fundamentally alters the nervous system and affects the individual at every level. We’re beginning to think of pain as more a disease in its own right. What’s still missing is a deeper understanding of its mechanisms.”
Pain is in the Brain
Pain is a complicated process that involves an intricate interplay of chemicals and signaling in the central nervous system. A stimulus, like a burn or incision, activates specialized nerve cells called nociceptors that carry the information to receptors that create the signal for pain. Most of this information is delivered to the thalamus, which plays a key role in relaying messages between the brain and parts of the body; from there the signals are passed along to the limbic system, which processes emotions, and the cortex, the headquarters for complex thoughts.
“The entire process serves as a negative feedback system, a balance of excitation and inhibition,” said Mackey. “After an injury like a sprain or a burn, the brain is rewired to protect itself, something that probably goes back to when man was hunting mammoths. The pain caused the body to slow down and heal, to be strong when it was time to go out mammoth hunting again. However, in a chronic pain condition like fibromyalgia the brain continues to send out pain messages even though there is no longer a stimulus. The system just doesn’t shut down.”
After a while, the pain alters brain activity and the nervous system. This results in multiple pathways within the brain that contribute to the pain experience. Mackey’s imaging studies of fibromyalgia patients have shown a dramatic increase in brain activity in areas affected by pain.
Because fibromyalgia’s effect on the brain involves the same brain regions and pathways involved with basic emotions, negative emotions like anger, stress or anxiety amplify the experience of pain. It correlates that it is important to control negative emotions because it can have a positive impact on pain.
Another negative consequence of chronic pain is that it can lead to premature aging of the brain and early degeneration of grey matter, said Mackey. This process affects regions of the brain involved with short-term memory and executive functioning, suggesting the “fibro fog” that patients complain of may be due to physical alterations within the brain.
Tools for Control
Mackey directs the Stanford Pain Management Center, an integrated, comprehensive program that treats more than 8,000 patients a year for pain, including chronic conditions like fibromyalgia. The Center is one of only 10 Clinical Centers of Excellence in the country, recognized as a national and international leader in pain management and rehabilitation.
Mackey and his associates assess the type and degree of pain and develop the best treatment, from pharmacological interventions to psychological and physiological therapies. Medications include antidepressants, analgesics, and anticonvulsants, all of which affect the brain’s perception of pain. Nonpharmacologic strategies for fibromyalgia include holistic approaches that utilize the mind-body connection, such as acupuncture, biofeedback, mental imaging, and cognitive behavioral therapy.
The center’s clinical work is closely liked with the School of Medicine’s Systems Neuroscience and Pain Lab, where Mackey and other scientists conduct research to understand the biological mechanisms of pain. One of their studies, supported by the American Fibromyalgia Syndrome Association, involves the use of naltrexone, an opioid blocker often used to treat addiction. At very low doses, the drug appears to slow down the central nervous system’s microglia cells, which overproduce chemical mediators related to illness behaviors (such as fatigue and soreness) in cases of fibromyalgia.
“Congress declared that this is the Decade of Pain Control and Research,” said Mackey. “Chronic pain is the nation’s leading public health problem and has long been overlooked as a health priority. We believe our work will make an even bigger impact on patients and on society.”
About the Speaker
Sean Mackey, MD, PhD, is a national leader in the study of pain and in developing new methods to control it. As the director of Stanford’s Division of Pain Management and an associate professor of anesthesia and pain management, he coordinates a multidisciplinary team of clinicians, nurses and scientists working to understand the neurological processes of pain and to identify new interventions. Mackey received his BS and MS in Bioengineering from the University of Pennsylvania and his MD and a PhD in Electrical Engineering from the University of Arizona. He completed his residency and fellowship at Stanford, where he joined the faculty in 2000.
For More Information:
Stanford Pain Management Center
Stanford Systems Neuroscience and Pain Lab
American Fibromyalgia Syndrome Association
National Fibromyalgia Association