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Motor cortex stimulation for pain control induces changes in the endogenous opioid system
J Maarrawi1, R Peyron, P Mertens
1INSERM U879, Bron, France joseph.maarrawi@chu-lyon.fr
Neurology
|August 29, 2007
Summary
Motor cortex stimulation (MCS) for neuropathic pain relief may involve the brain's natural pain-killing system. This study found that MCS reduced opioid receptor availability, suggesting the release of endogenous opioids, which correlated with pain reduction.
Area of Science:
- Neuroscience
- Pain Management
- Neuroimaging
Background:
- Motor cortex stimulation (MCS) is used for neuropathic pain.
- MCS affects cerebral blood flow in opioid receptor-rich areas.
- The role of the endogenous opioid system in MCS pain relief is unclear.
Purpose of the Study:
- To investigate the endogenous opioid system's contribution to MCS-induced pain relief.
- To assess changes in opioid receptor availability during chronic MCS therapy.
Main Methods:
- Positron Emission Tomography (PET) scans with [(11)C]diprenorphine were used.
- Eight patients with refractory neuropathic pain were studied.
- Scans were performed pre- and post-MCS treatment (7 months).
Main Results:
- No significant differences in opioid receptor binding between preoperative scans.
- Postoperative scans showed decreased [(11)C]diprenorphine binding in key brain regions (aMCC, PAG, prefrontal cortex, cerebellum).
- Reduced binding in anterior middle cingulate cortex (aMCC) and periaqueductal gray (PAG) correlated with pain relief.
Conclusions:
- Decreased ligand binding suggests receptor occupancy by endogenous opioids.
- MCS may trigger the release of endogenous opioids in pain-processing brain areas.
- The endogenous opioid system plays a role in MCS-mediated pain control.
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