Veränderungen der spinalen und supraspinalen Schmerzwahrnehmung bei Patienten mit M. Parkinson

Patients suffering from Parkinsons disease (PD) often complain about painful sensations. Recent studies detected increased subjective pain sensitivity and increased spinal nociception, which appeared reversible by dopaminergic treatment. Possibly, reduced descending pain inhibition contributes to this finding. We investigated the diffuse noxious inhibitory control (DNIC) system as one form of descending control in addition to subjective pain thresholds and nociceptive reflex thresholds. Fifteen patients with PD (measured during the medication-free period in the morning) and eighteen controls participated in the study. Thermal heat and electrical pain thresholds as well as the nociceptive flexion reflex (NFR) thresholds were determined. Thereafter, the electrical pain thresholds were measured once during painful heat stimulation (conditioning stimulation) and twice (before and after conditioning) during innocuous stimulation (baseline stimulation). The PD patients exhibited lower electrical and heat pain thresholds as well as lower NFR thresholds. The suppression of the electrical pain thresholds during painful heat stimulation compared to baseline stimulation did not differ significantly between the groups. No differences of the thresholds between PD patients with and without clinical pain were seen. Finding the NFR threshold to be decreased in addition to the decreased electrical and heat pain thresholds indicates that the pathophysiological changes either already reside at or reach down to the spinal level. A reduced activation of the DNIC system did apparently not contribute to the increased pain sensitivity, suggesting a normal functioning of this part of the endogenous pain inhibitory system in PD.