Real-Time Functional Magnetic Resonance Imaging in Pain Management
Chronic pain is debilitating to the patient and puts an enormous strain on the healthcare delivery system. It is the primary complaint resulting in physician visits and the use of healthcare resources. 1 Chronic pain costs the United States about $150 billion a year. 2 The purpose of this study is to review the current literature on the use of functional Magnetic Resonance Imaging (fMRI) in pain management and to suggest a range of potential future applications. These include alternative therapy for chronic pain sufferers, pharmacological research in the development and testing of new analgesics, real-time feedback for osteopathic manipulative techniques to ease pain, the creation of new objective pain scales, and brain mapping of specific pain types. These potential applications could have a major impact on improving the quality of life and functional ability of chronic pain patients, who often have great difficulty controlling pain that is often unresponsive to traditional treatment. They also could help to reduce the enormous burden that chronic pain puts on the healthcare delivery system.
Functional Magnetic Resonance Imaging
Magnetic resonance imaging—traditionally used for anatomical imaging—is now widely used to observe brain structures and functions. Recent advances in computing power and software make it possible for the patient and doctor to view the subject’s brain as it functions in nearly real time. By observing the functioning of their own brain’s pain system, patients have been trained to reduce the level of severe, chronic pain significantly. 3 This could offer relief for the estimated 50 million to 80 million Americans living with chronic pain.
Functional magnetic resonance imaging, or fMRI, could be the most suitable candidate for routine clinical use in the evaluation of pain. 4 Long-term changes in brain structures have been linked to the exaggeraged brain activity of chronic pain patients. Researchers have found that individuals with chronic back pain sustained alterations in the functional connectivity of the cortical regions. 5 These areas of the brain are related to emotions. The non-stop firing of neurons in the frontal part of the cortex changes the neurons’ connections and can lead to depression, anxiety, sleep disturbances and cognitive dysfunction.
Functional MRI shows the amount of blood flow to specific brain regions and so provides an indirect indication of brain activity. Chronic pain disrupts the natural resting state of the brain, known as the default mode network (DMN). Patients with chronic back pain show less neocortical gray matter volume than control patients, but this gray matter atrophy can be reversed. 6 The brain matter decrease is the consequence and not the cause of pain.
According to researchers at University College London, functional MRI can be used as a new paradigm in cognitive neuroscience to study brain plasticity and the functional relevance of brain areas. 7 Online analysis of single-subject data provides immediate quality assurance. It also provides functional localizers guiding experiments or surgical interventions. Functional MRI allows for brain-computer interfaces (BCI), with a high spatial and temporal resolution and whole brain coverage.
Honda Research Institute Japan and the Advanced Telecommunications Research Institute International have created the first brain-machine interface that enables control of a robot by thought alone. The technology uses a functional MRI scanner and achieved the first success in the world to control a robot hand by decoding brain activities without electrode array implants or special training of the user. The technology is described in a corporate news release issued by Honda in 2009. 8
Researchers at University Hospital Basel in Switzerland found that real-time functional MRI feedback training may improve chronic tinnitis, a more or less constant ringing in the ears. 9 The excess auditory activation significantly decreased after fMRI neurofeedback.
According to Columbia University’s Program for Imaging and Cognitive Sciences (PICS), the number of medical research centers with functional MRI capabilities continues to grow. The technology provides the ability to observe the brain structures and also to discern which structures participate in specific functions. PICS’ website 10 states that fMRI provides high-resolution images without the need to inject radioactive isotopes. It can be used to noninvasively map changes in brain hemodynamics that correspond to mental operations. Columbia University says its pilot studies of patients with chronic sympathetically-maintained pain affecting one extremity suggest a wide range of other approaches using fMRI to investigate cortical representations of specific pain types and, therefore, new specific therapy options.
Self-Regulation Using fMRI
Much of the early research in the use of fMRI to train patients in pain management was done at Stanford University and is being continued in conjunction with a private company, Omneuron, Inc. at Menlo Park, California. In a few brief sessions, each lasting 13 minutes, patients can learn to control activity in different parts of their brain and change their sensitivity to painful stimuli. Individuals can learn to exert deliberate, voluntary control over localized brain activation by using real-time fMRI as feedback. 3
Richard Chapman, director of the Pain Research Center at the University of Utah in Salt Lake City, says it should eventually be possible to identify patterns of brain activity involved in perpetuating chronic pain and then to introduce interventions that we know from published evidence can block or compete with those patterns. 2 Researchers at Northwestern University in Chicago found that a stimulus which healthy human subjects perceive as a reward might be processed quite differently in the brains of chronic pain sufferers. 11 The findings point to a possible dysfunctional associative learning process in chronic pain patients.