The new Parkinson's disease pain classification system (PD-PCS)

Background Chronic pain is a common non-motor symptom in patients with Parkinson's disease (PD). Aim To facilitate the diagnosis of pain in PD, we developed a new classification system the Parkinson's disease pain classification system (PD-PCS) and translated the corresponding validated questionnaire into German. Methods A causal relationship of the respective pain syndrome with PD can be determined by four questions before assigning it hierarchically into one of three pain categories (neuropathic, nociceptive and nociplastic). Results In the initial validation study 77% of the patients (122/159) had PD-associated pain comprising 87 (55%) with nociceptive, 36 (22%) with nociplastic and 24 (16%) with neuropathic pain. The study revealed a high validity of the questionnaire and a moderate intrarater and interrater reliability. The questionnaire has been adapted into German and employed in 30 patients. Discussion The PD-PCS questionnaire is a valid and reliable tool to determine the relationship of a pain syndrome with PD before classifying it according to the underlying category, facilitating further diagnostics and treatment.