Unveiling the relationship between central parkinsonian pain and motor symptoms in Parkinson's disease.

BACKGROUND: Pain in Parkinson's disease (PD) is a common and heterogeneous non-motor symptom. Although the characteristics and predictors of pain in general and of central pain in particular are still largely unknown. METHODS: A semi-structured interview, the Brief Pain Inventory and the Pain Disability Index were used to identify and characterize pain in a consecutive series of 292 PD patients. Unified PD Rating Scale-III, Hoehn & Yahr, Schwab and England Independence Scale and Freezing of Gait Questionnaire were applied to assess motor symptoms and functional independence in off and on conditions. Hospital Anxiety and Depression Scale and Questionnaire of Impulsive-Compulsive Control Disorders were used to screen for anxiety, depression and impulse control disorders. RESULTS: Two hundred and twelve patients (73%) reported pain, which was classified as: musculoskeletal (63%), dystonia-related (27%), central parkinsonian (22%) and/or radicular or neuropathic (9%). Patients with pain had more comorbidities and more severe motor symptoms. Patients with central parkinsonian pain were significantly younger, had earlier disease onset, fewer comorbidities, greater non-axial motor symptom severity in on, more pain-related disability and more relief of pain with antiparkinsonian medication than patients with non-central parkinsonian pain. CONCLUSIONS: PD patients with central parkinsonian pain have some distinctive demographic and clinical features, including lower levodopa responsiveness of motor appendicular/limb symptoms to levodopa, associated with greater responsiveness of pain symptoms to these same medications. These findings suggest the need for a more integrated approach to motor and non-motor symptoms in these patients' clinical care. SIGNIFICANCE: In a consecutive series of 292 patients with PD, almost three quarters of patients with PD reported pain. The study results revealed that pain was related to more severe motor symptoms, anxiety symptoms and comorbidities. Among patients with pain, those with central parkinsonian subtype had distinct demographic and clinical features, including lower levodopa responsiveness for non-axial motor symptoms and greater responsiveness of pain to antiparkinsonian treatment.