Unraveling gait and balance impairment in cervical dystonia: associated features, functional implications, and the effect of botulinum toxin

Background: Cervical dystonia (CD) may affect not only head posture but also gait and balance. The relationship between quantitative gait abnormalities and perceived disability, the contribution of head tremor (HT) and the impact of botulinum toxin (BoNT) on these disturbances remain unclear. Methods: We analyzed gait and balance in twenty-one CD patients (nine with HT) and twenty-two healthy controls (HC) by wearable sensors. Validated scales for CD severity, pain and quality of life (Tsui; TWSTRS-2; CDQ24; CDIP58) were used and CD patients re-evaluated one month after BoNT. Functional impact of gait impairment was assessed by multivariate analyses. Results: Compared with HC, CD patients showed reduced gait speed, cadence, and stride length, longer double-support time, greater stride-length variability (SLV), and increased postural sway (all p < 0.05). SLV was the only gait parameter associated with the CDIP58-Walking subscale (p = 0.003) and remained an independent predictor after age, sex, CD-duration and CD-severity adjustment (p = 0.035). Patients with HT had greater sway than those without tremor after adjusting for disease severity (p = 0.038). All gait and balance parameters were similar after BoNT, except for reduced gait asymmetry. In the HT subgroup, sway improved significantly (p = 0.011). Conclusions: This study confirms subtle gait and balance abnormalities in CD, with SLV emerging as a potential biomarker of functional impairment. HT appears to exacerbate balance dysfunction, while BoNT may partly improve sway in this subgroup. These findings suggest that sensor-based gait analysis may complement clinical evaluation and guide management in CD.