Interventions on emotional responses to pain stimuli in patients with chronic neuropathic pain
To characterize the sensory and emotional components of the responses to repeated pain stimuli in patients with chronic neuropathic pain.
To quantify the effects of non-invasive central nervous system interventions on sensory and emotional components of pain.
1. Subjects: Patients with peripheral or central nervous system lesions with and without neuropathic pain. Age-matched healthy volunteers will also participate in some experiments.
2. Psychological and psychophysiological evaluation: Clinical interview, scales of evaluation of mood and cognition, and visual analog scale scores, will be used to establish baseline conditions. The emotional response to phasic stimuli will be assessed by recording physiological autonomic nervous system responses (sudomotor skin response of the hand and heart beat frequency changes).
3. Neurophysiological and neuroradiological evaluation: Pain-related cerebral activity will be recorded by means of contact heat evoked potentials (CHEPs), and functional magnetic ressonance imaging (fMRI).
4. Interventions. Repetitive transcranial magnetic stimulation (rTMS) will be used to modify cortical excitability and organization. In addition, virtual reality systems will be used to promote re-organization of central nervous system circuits.
We expect to find different neurophysiological and neuroimaging features of the sensory and emotional components of pain. We expect also that our interventions cause a significant change in both the emotional reaction to pain stimuli and their neuronal organization.