Structural MRI Analysis of Chronic Pain Patients Following Interdisciplinary Treatment Shows Changes in Brain Volume and Opiate-Dependent Reorganization of the Amygdala and Hippocampus.

Objective: The present study examined pre- to post-treatment changes in volumes for brain structures known to be associated with pain processing (thalamus, caudate, putamen, pallidum, hippocampus, amygdala, and accumbens) following an interdisciplinary pain management program.

Design: Twenty-one patients participating in a four-week interdisciplinary pain management program completed the study. The program consisted of individual and group therapies with the following disciplines: physical therapy, occupational therapy, pain psychology, biofeedback/relaxation training, nursing lectures, and medical management. All patients underwent functional magnetic resonance imaging of the brain before the start and at completion of the program. They also completed standard outcome measures assessing pain, symptoms of central sensitization, disability, mood, coping, pain acceptance, and impressions of change.

Results: Our results showed a significant increase in total brain volume, as well as increased volumes in the thalamus, hippocampus, and amygdala. As expected, we also found significant improvements in our standard outcome measures. The majority of patients rated themselves as much or very much improved. The increase in volume in the hippocampus was significantly associated with patient perceptions of change. However, the correlations were in the unexpected direction, such that greater increases in hippocampal volume were associated with perceptions of less improvement. Further exploratory analyses comparing patients by their opioid use status (use vs no use) showed differential program effects on volume increases in the hippocampus and amygdala.

Conclusions: These findings show that a four-week interdisciplinary pain management program resulted in changes in the brain, which adds objective findings further demonstrating program efficacy.