http://www.medscape.com/viewarticle/531729_13

New Advanced Imaging Techniques in the Diagnosis of Pain Syndromes
Sean Mackey, MD, PhD,[39] gave a fascinating lecture on the work being done in neural imaging of pain states. He pointed out the limitations of animal models, namely, that most tests are for threshold, which may not be meaningful for clinical pain and do not capture the complex pain experience, which includes psychological, psychosocial, and environmental factors.

On the basis of the results from functional magnetic resonance imaging (fMRI) studies, the following brain areas have been shown to contribute to the perception of somatic pain:

1.Primary and secondary somatosensory cortex;


2.Anterior cingulated gyrus;


3.Amygdalae;


4.Thalamus;


5.Midinsular cortex;


6.Prefrontal cortex; and


7.Posterior cerebellum.
Dr. Mackey reviewed the seminal study by Robert Coghill, PhD, of Wake Forest who studied 17 healthy volunteers, subjecting each to a range of thermal stimuli (43-49C), with fMRI and positron emission tomography scan regression analysis being done for 49C.[40] Individual differences in the subjective experiences of pain were reported with medial prefrontal gyrus and somatosensory cortex becoming active in a subset who rated pain as severe (8 of 10) from the remainder (3 of 10). In imaging of painful conditions, when normal volunteers were compared to those with CRPS or back pain, only the anterior cingulated gyrus showed overlap -- in those with CRPS, significant changes indicating somatotopic reorganization and neural plasticity were evident.

Future directions in the diagnosis of pain syndromes are to (1) use fMRI to image the brain and spinal cord to understand neural plasticity in pain and to develop treatments to reverse it, (2) to use fMRI to better understand emotional and cognitive aspects of pain and how it affects the processes of chronic pain, and (3) to institute the use of real-time fMRI as a treatment tool for the everyday pain practitioner.