Parkinsonism & related disorders
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Parkinsonism Relat. Disord. · Jan 2017
Abnormal nociceptive processing occurs centrally and not peripherally in pain-free Parkinson disease patients: A study with laser-evoked potentials.
Several studies documented abnormal nociceptive processing in PD patients. Pain central pathways are accessible by laser-evoked potentials (LEPs). LEPs recording show a N2/P2 complex mostly generated by the anterior cingulate cortex, preceded by an earlier negative component (N1), originating from the opercular cortex. Previous work demonstrated N2/P2 amplitude reduction in PD patients and suggested a centrally-acting pathomechanism for the genesis of pain. However, since a peripheral deafferentation has been recently demonstrated in PD, it is not clear if such LEP abnormalities reflect a mechanism acting centrally or not. ⋯ These findings demonstrate that in the PD patients the abnormal processing of pain stimuli occurs at central rather than peripheral level. The co-existence of hyperalgesia and reduced amplitude of the N2/P2 complex, in spite of a normal N1/P1 component, suggests an imbalance between the medial and lateral pain systems. Such a dissociation might explain the genesis of central pain in PD.