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Benefits, Safety, and Adjunct Modality Prevalences of Long-Term Botulinum Toxin Injections for Cervical Dystonia and Myofascial Neck Pain: A Retrospective Cohort Study

Authors Diep D, Ko J, Lan J, Koprowicz KT, Ko G

Received 15 March 2020

Accepted for publication 29 April 2020

Published 3 June 2020 Volume 2020:13 Pages 1297—1304


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Robert B. Raffa

Dion Diep,1 Jasmine Ko,2 John Lan,3 Kinga T Koprowicz,3 Gordon Ko3,4

1MD Program, University of Toronto, Toronto, ON, Canada; 2Department of Kinesiology, McMaster University, Hamilton, ON, Canada; 3Canadian Centre of Integrative Medicine, Toronto, ON, Canada; 4Division of Physical Medicine & Rehabilitation, Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Correspondence: Gordon Ko
Clinical Adjunct Lecturer, Division of Physical Medicine & Rehabilitation, Sunnybrook Health Sciences Centre, 2075 Bayview Ave, Toronto, ON M4N 3M5, Canada
Tel +1416-480-4342
Fax +1416-480-6885

Introduction: There is a paucity of long-term treatment benefit and safety data of botulinum toxin A (BTX-A) for cervical dystonia (CD) and myofascial neck pain syndrome (MPS). Additionally, the prevalence of adjunct modality uses during this period is unknown despite evolving practices.
Objective: To assess and compare treatment benefit, safety, and adjunct modality prevalences of long-term BTX-A injections between CD and MPS patients.
Design: Retrospective cohort study.
Setting: Private practice tertiary care clinics in Toronto.
Patients: Convenience sample of 37 (52.9%) CD and 33 (47.1%) MPS patients treated for a mean±SD duration of 7.2± 4.3 and 8.3± 4.7 years, respectively.
Interventions: BTX-A injections administered at least once yearly, for a duration longer than 1 year.
Main Outcome Measures: Toronto Western Spasmodic Torticollis Rating Scales (TWSTRS) for disability and pain, Patient Global Impression of Change (PGIC) score, time to peak effect, duration of total response, adverse effects, and prevalence of adjunct modalities.
Results: CD patients experienced improvements in TWSTRS disability (17.57± 6.79 to 9.81± 4.35, p< 0.001) and pain (14.61± 3.08 to 9.05± 3.49, p< 0.001) scores as well as PGIC score (52.00%± 23.60% to 64.80%± 23.60%, p=0.007). MPS patients experienced improvements in TWSTRS disability (15.86± 7.70 to 10.07± 7.01, p=0.01) and pain (15.25± 4.09 to 10.85± 4.49, p=0.01) scores. In both cohorts, there were no changes in time to peak effect and duration of total response. Adverse effects were minimal and self-limiting. Prevalences of adjunct modalities used by CD versus MPS patients were 28.13% versus 50.00% for anesthetic procedures, 23.08% versus 15.38% for image-guidance, 65.71% versus 56.25% for pectoralis minor injections, and 47.06% versus 53.13% for cannabis-use.
Conclusion: There were demonstrated and comparable treatment benefit, safety, and adjunct modality prevalences. Our study is the first to demonstrate that long-term BTX-A injections for MPS, although commonly used off-label, can be effective and safe.

Keywords: botulinum toxin, cervical dystonia, myofascial pain syndrome

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