failure to recruit

Neuropathic pain is a medical condition involving allodynia (painful perceptions in response to stimuli that normally are not) and spontaneous pain (occurring at rest, without stimulation).

This pain is secondary to nervous system injury affecting the sensory system. The lesion is either at the nerve endings of the spinal cord or brain.

It induces a loss of sensitivity and likely reorganization of brain activity that are causing pain and which are the subject of this study.

Previous studies in functional neuroimaging has focused on brain areas activated during allodynic stimuli compared to non-painful stimuli. The abnormalities have been reported, but it was not possible to conclude formally. The authors failed to assess the part of the effect of the loss of sensory afferents (deafferentation) and the basal brain function.

Indeed, the operation without any sensory stimulation is not known yet is the initial level of activity which is the benchmark for studying brain function during stimulation. The objective of this study is to understand what are the cortical systems of allodynic dysfunctional in patients compared with controls at baseline.

Inclusion Criteria for patients :

• major
• with nervous pain : chronic or peripheric
• treatment not stable opioid since one week
• signed consent

Inclusion Criteria for witnesses :

• major
• without chronic pain
• signed consent

Exclusion Criteria for 2 groups :

• severe psychiatric history
• presence of an active nervous lesion
• subject with morphine treatment
• contraindication to MRI scan