Pain characteristics in isolated cervical dystonia: comparison to orthopedic cervical conditions and assessment of botulinum toxin effects.

The objective was to characterize pain and evaluate quality of life (QoL) in cervical dystonia (CD) by comparing pain profiles with patients affected by orthopedic cervical conditions (OCC) and evaluating differences between CD patients with and without head tremor (HT). Additionally, longitudinal changes after botulinum toxin (BoNT) treatment in CD were assessed. Pain is the most prevalent non-motor symptom in CD. However, its clinical characteristics and underlying mechanisms are incompletely understood. Isolated CD and OCC patients were evaluated regarding pain characteristics and QoL using self-report questionnaires. CD patients additionally underwent blinded motor assessment and were stratified according to the presence of HT. A subset of CD patients was reevaluated 4-6 weeks after BoNT treatment. 49 CD patients and 49 OCC patients were investigated. The overall pain profile was comparable between CD and OCC; only nociceptive pain perception was higher in OCC than in CD. HT in CD patients was associated with increased nociceptive pain and greater QoL impairment. Following BoNT injection in CD, pain and QoL improved significantly. The marked similarities of pain profiles in CD and OCC together with the increased nociceptive pain in CD patients with HT suggest that musculoskeletal mechanisms contribute to pain in CD. Improvement of pain and QoL in CD patients with long disease duration after BoNT treatment indicates the relevant effect on non-motor symptoms. Further studies are needed to clarify the underlying pathophysiology of pain in CD.