Prevalence and treatment effects on non-motor symptoms in cervical dystonia: A systematic review and meta-analysis

Non-motor symptoms (NMS) substantially impair quality of life in patients with cervical dystonia (CD). Although psychiatric comorbidities are well recognized, the prevalence of sleep disturbance and fatigue in this population remains unclear; likewise, whether therapeutic interventions ameliorate NMS has not been established. This systematic review and meta-analysis evaluated NMS prevalence, identified moderators of heterogeneity, and assessed treatment effects on NMS in patients with CD.

Following PRISMA standards (PROSPERO: CRD42024619105), we searched Embase, PsycINFO, PubMed, and Web of Science through May 1, 2026. We calculated pooled prevalence using random-effects models, and conducted subgroup analyses and meta-regression to identify sources of heterogeneity. Treatment outcomes were assessed using standardized mean differences.

Forty-two studies were included. Pooled prevalence rates were: depression 35.2% (95% CI, 30.0% to 40.6%; I² = 84.8%), anxiety 34.0% (95% CI, 27.8% to 40.5%; I² = 85.8%), sleep disturbance 57.1% (95% CI, 46.7% to 67.2%; I² = 84.4%), and fatigue 60.6% (95% CI, 49.1% to 71.6%; I² = 54.9%). Assessment tool type was the most consistent source of heterogeneity. Meta-regression identified female percentage as a potential moderator of depression prevalence; no moderator reached significance for anxiety. Botulinum toxin treatment produced an improvement in depression (SMD = -0.31) and anxiety (SMD = -0.23), but no significant benefit for sleep disturbance. Substantial heterogeneity persisted across most analyses.

NMS were highly prevalent in CD, with over half of patients reporting sleep disturbance or fatigue. Assessment tool type was the most consistent source of heterogeneity across outcomes, highlighting the need for standardized NMS assessment protocols. Meta-regression identified female percentage as a potential moderator of depression prevalence. Among interventions, BoNT provided preliminary evidence of modest benefit for mood symptoms but had no effect on sleep. The evidence base for NMS interventions in CD remains preliminary, underscoring the need for trials explicitly aimed at NMS.