Pains in Parkinson disease--many syndromes under one umbrella

Pain is a nonmotor symptom that substantially affects the quality of life of at least one-third of patients with Parkinson disease (PD). Interestingly, patients with PD frequently report different types of pain, and a successful approach to distinguish between these pains is required so that effective treatment strategies can be established. Differences between these pains are attributable to varying peripheral pain mechanisms, the role of motor symptoms in causing or amplifying pain, and the role of PD pathophysiology in pain processing. In this Review, we propose a four-tier taxonomy to improve classification of pain in PD. This taxonomy assigns nociceptive, neuropathic and miscellaneous pains to distinct categories, as well as further characterization into subcategories. Currently, treatment of pain in PD is based on empirical data only, owing to a lack of controlled studies. The facultative symptom of 'dopaminergically maintained pain' refers to pain that benefits from antiparkinson medication. Here, we also present additional pharmacological and nonpharmacological treatment approaches, which can be targeted to a specific pain following classification using our taxonomy.