Background: Chronic pain is a major public health problem resulting in physical and emotional pain for individuals and families, loss of productivity, and an annual cost of billions of dollars. The lack of objective measures available to aid in diagnosis and evaluation of therapies for chronic pain continues to be a challenge for the clinician.
Objectives: Functional magnetic resonance imaging (fMRI) is an imaging technique that can establish regional areas of interest and examine synchronous neuronal activity in functionally related but anatomically distinct regions of the brain, known as functional connectivity.
Study design: The present investigation examines changes in functional connectivity in 4 common pain syndromes: chronic back pain (CBP), fibromyalgia, diabetic neuropathy, and complex regional pain syndrome (CRPS).
Setting: This is a review of the current understanding of functional connectivity.
Methods: Utilizing functional imaging, patients with these conditions have been shown to have significant structural and functional differences when compared to healthy controls.
Results: Functional connectivity, therefore, has the potential to assist in diagnostic classification of different pain conditions, predict individual responses to specific therapeutic interventions, and serve as a gateway for personalized medicine. Indirect activation of brain activity can be seen by the blood flow to the brain at specific sites, with chronic pain patients having increased brain activity.
Limitations: The present investigation is limited in that few studies have examined this relatively new modality.
Conclusions: Knowing and observing the brain's activity as related to pain gives pain patients an opportunity to decrease pain-related brain activity and decrease severe chronic pain. This modality can be used along with interventional pain management techniques in order to provide optimum pain relief.
Key words: Functional connectivity, fMRI, chronic pain, chronic back pain, fibromyalgia, diabetic neuropathy, chronic regional pain syndrome.