How to diagnose parkinsonian central pain?

Among the different types of pain observed in Parkinson's disease, parkinsonian central pain (PCP) has the highest severity, and is poorly characterized and difficult to describe not only by patients but also by neurologists. Thus PCP remains not strictly defined and is difficult to distinguish from other types of pain on the basis of clinical description. Yet, standardizing PCP diagnosis is critical to improve the treatment of this debilitating pain subtype, but also to homogenize further studies investigating the pathophysiological mechanisms underlying this condition. Accounting for the lack of reliable validated positive clinical criteria for PCP, and as the clinical features of PCP are difficult to specify, we suggest to consider so far the gold standard diagnosis of PCP mainly based on exclusion criteria. We propose a new algorithm aiming to disentangle PCP from other chronic pain subtypes in Parkinson's disease, by sequentially ruling out what PCP is not.