Clinical pain and experimental pain sensitivity in progressive supranuclear palsy

Objective: We aimed to assess spinal nociception and experimental pain sensitivity in progressive supranuclear palsy-Richardson's syndrome (PSP-R) compared to patients with Parkinson's disease (PD) and healthy controls (HC). Methods: Spinal nociception as measured by the nociceptive flexion reflex (NFR) and experimental pain sensitivity as measured by heat and electrical pain thresholds were determined in non-demented, non-depressed, probable PSP-R patients (N = 8), PD patients (N = 19) and 17 HC. Results: PSP-R patients exhibited lower electrical pain thresholds and a tendency for lower NFR thresholds as compared to HC. No significant differences between PSP-R and PD patients were found with respect to experimentally-induced pain. However, significantly less PSP-R than PD patients reported disease-related pain. Conclusions: Degeneration of the descending inhibitory control system within the brainstem in PSP-R might lead to increased experimental pain sensitivity while frontal cortical deterioration may alter self-estimation of pain.