Objective: To assess the impact of botulinum toxin injections (BoNT) on anxiety symptoms and motor symptoms in cervical dystonia (CD) during one treatment cycle.

Background: Anxiety is common in CD and is present in 30-40% of patients. [1] While historically it has been ascribed to a direct effect of the state of motor symptoms, there is debate about anxiety being a distinct trait of the dystonia syndrome. [2,3] Accordingly, the relative impact of BoNT on anxiety and motor symptoms is inadequately understood.

Method: In this prospective observational study, 60 participants with idiopathic CD were recruited at the time of their clinical BoNT appointment. Based on established literature, using an effect size estimate (d=0.59, f=0.295), a sample size of 58 subjects was found to afford sufficient power (1-β > 0.80) to detect a significant difference in both STAI-T and STAI-S between pre-BoNT and post-BoNT, using a repeated measures general linear model with alpha set at p = 0.05. [4]

Motor and anxiety symptom burden was assessed by Toronto Western Spasmodic Torticollis Rating Scale 2 (TWSTRS-2) parts I-III and State-Trait Anxiety Inventory (STAI) at time of BoNT and at 6 weeks post-injection during the period of maximal treatment effect. Response of motor and non-motor symptoms to BoNT was assessed by comparing STAI and TWSTRS-2 scores at baseline and 6 weeks post injection. Spearman rank correlation was used to correlate anxiety scores with CD motor symptom burden. Scores were compared using paired T-test for normally distributed data, and Wilcoxon signed rank test for data with non-parametric distribution.

Results: Our sample was 71.7% female with a mean age of 60.65 years. Mean disease duration was 19.03 years. The mean duration of BoNT was 9.51 years. There was poor correlation between STAI and motor TWSTRS-2 scores at baseline visit (rho = -0.30, p=0.411). Motor TWSTRS-2 (M_difference = -1.46, p < .024) and STAI (M_difference = -10.37, p = 0.007) both improved from baseline to 6 weeks. Difference in motor TWSTRS-2 scores from baseline to 6 weeks did not correlate with difference in STAI scores during the same time (rho = -0.14, p>.999).

Conclusion: Baseline anxiety severity and motor severity poorly correlate with each other in CD. BoNT improves both anxiety and motor severity at 6 weeks. Improvement in anxiety seen with BoNT is unlikely to be secondary to motor improvement.

References: 1. Klingelhoefer L, Martino D, Martinez-Martin P, et al. Nonmotor symptoms and focal cervical dystonia: Observations from 102 patients. Basal Ganglia. 2014;4(3-4):117-120.
2. Medina EA, Martino D, Goodarzi Z. The prevalence of anxiety in adult-onset isolated dystonia: A systematic review and meta-analysis. Eur J Neurol. 2021;28(12):4238-4250.
3. Kuyper DJ, Parra V, Aerts S, Okun MS, Kluger BM. Nonmotor manifestations of dystonia: A systematic review. Mov Disord. 2011;26(7):1206-1217.
4. Gilbertson-White S, Aouizerat BE, Jahan T, et al. Determination of cutpoints for low and high number of symptoms in patients with advanced cancer. J Palliat Med. 2012;15:1027–1036.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-effect-of-botulinum-toxin-on-anxiety-in-cervical-dystonia/