[Note: Broadly, “pain disorder” involves chronic pain in one or more parts of the body. Symptoms are physical but without identified physiological cause.]
Objective: To investigate whether the functional changes in pain disorder might be reflected by structural brain changes.
Pain disorder assessed with the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria is characterized by persistent and distressing chronic pain at one or more body sites which cannot be fully explained by a physiological process or somatic disorder. Psychological factors are thought to play a major role.
Recent neuroimaging studies evidenced altered pain processing in patients suffering from this disorder.
Methods: Fourteen right-handed women fulfilling the DSM-IV criteria for pain disorder and 25 healthy age-matched women were investigated with magnetic resonance imaging.
In the voxel-based morphometry analysis, we compared both groups for changes of gray-matter density. We included age and Beck Depression Inventory scores as nuisance variables to minimize possible confounding effects of age or depressive comorbidity.
Results: In the patient group, we found significant gray-matter decreases in the prefrontal, cingulate, and insular cortex. These regions are known to be critically involved in the modulation of subjective pain experiences.
Conclusions: In the context of similar results in patients with other functional pain syndromes, such as fibromyalgia and chronic back pain, we suggest that structural changes in fronto-limbic brain circuits represent not only an objective marker of these pain syndromes but also constitute a critical pathophysiological element.
These findings represent a further proof of the important role of central changes in pain disorder.
Source: Psychosomatic Medicine, Dec 10, 2008. [E-pub ahead of print.] PMID: 19073757, by Valet M, Gündel H, Sprenger T, Sorg C, Mühlau M, Zimmer C, Henningsen P, Tölle TR. Neurologische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universitat München, Germany. [E-mail: firstname.lastname@example.org]