Temporal discrimination at the neck region is associated with severity of cervical dystonia

Cervical dystonia (CD) is a rare movement disorder marked by involuntary neck muscle contractions. Although somatosensory dysfunction has been proposed, the underlying pathophysiology remains unclear. Temporal discrimination (TD) deficits are discussed as potential markers of a dystonic endophenotype, possibly linked to proprioceptive impairments. This study aimed to assess TD in the neck region and explore its relationship with proprioception in head movements. We evaluated somatosensory temporal discrimination threshold (STDT) and temporal discrimination movement threshold (TDMT) in 20 CD patients and 20 healthy controls (HC). Both measures were applied directly to the cervical region: STDT via skin stimuli on the lateral neck and TDMT via muscle stimuli to the splenius capitis. Proprioception was assessed through a head rotation task. Clinical severity was measured using the TWSTRS scale. STDT and TDMT thresholds were significantly elevated in CD patients compared to HCs and correlated positively with dystonia severity. However, there were no group differences in proprioceptive performance, nor was proprioception correlated with TD or TWSTRS scores. TD is clearly altered in CD and associated with symptom severity, supporting its role in dystonia pathophysiology. In contrast, no proprioceptive deficits were observed, and no link between TD and proprioception was found. This suggests TD and proprioception may represent distinct dysfunctions rather than connected elements of sensorimotor integration. Further studies are needed to refine proprioceptive testing in CD and clarify its relationship with TD.