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Toxicon. 2018 Jun 1;147:89-95. doi: 10.1016/j.toxicon.2017.09.004. Epub 2017 Sep 6.

Longitudinal studies of botulinum toxin in cervical dystonia: Why do patients discontinue therapy?

Author information

Departments of Neurology, Human Genetics and Pediatrics, Emory University, Atlanta, GA, United States. Electronic address:
Department of Neurology, Rush University Medical Center, Chicago, IL, United States.
Departments of Neurology, Radiology, Neuroscience, and Physical Therapy and Occupational Therapy, Washington University School of Medicine, St. Louis, MO, United States.
Division of Clinical Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.
Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.



Numerous studies have established botulinum toxin (BoNT) to be safe and effective for the treatment of cervical dystonia (CD). Despite its well-documented efficacy, there has been growing awareness that a significant proportion of CD patients discontinue therapy. The reasons for discontinuation are only partly understood.


This summary describes longitudinal studies that provided information regarding the proportions of patients discontinuing BoNT therapy, and the reasons for discontinuing therapy. The data come predominantly from un-blinded long-term follow-up studies, registry studies, and patient-based surveys.


All types of longitudinal studies provide strong evidence that BoNT is both safe and effective in the treatment of CD for many years. Overall, approximately one third of CD patients discontinue BoNT. The most common reason for discontinuing therapy is lack of benefit, often described as primary or secondary non-response. The apparent lack of response is only rarely related to true immune-mediated resistance to BoNT. Other reasons for discontinuing include side effects, inconvenience, cost, or other reasons.


Although BoNT is safe and effective in the treatment of the majority of patients with CD, approximately one third discontinue. The increasing awareness of a significant proportion of patients who discontinue should encourage further efforts to optimize administration of BoNT, to improve BoNT preparations to extend duration or reduce side effects, to develop add-on therapies that may mitigate swings in symptom severity, or develop entirely novel treatment approaches.


Botulinum toxin; Cervical dystonia; Dystonia; Torticollis; Treatment

[Available on 2019-06-01]
[Indexed for MEDLINE]

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