Long-term response in clinical practice to the application of botulinum neurotoxin type A in patients with cervical dystonia

Background: Cervical dystonia (CD) is the most common form of focal dystonia, in which application of botulinum neurotoxin type A (BoNT-A) is the first-line treatment. However, information related to its long-term effectiveness is sparse. The aim of this study was to evaluate satisfaction and clinical response in patients with CD. Methods: An international, observational, multi-center, and prospective study was conducted (INTEREST IN CD2) to evaluate the course of patients treated with BoNT-A over 3 years, with intermediate assessments at each injection visit. This is a sub-analysis that considers information from Latin American countries (Mexico and Brazil). Data from patients with CD were collected in an electronic case report form. The main outcomes were satisfaction at the time of the visit, before BoNT-A injection, regarding the control of the symptoms assessed with a Likert scale and the CD features evaluated by Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Descriptive statistics were performed considering the significance of 95%. Results: Data from 79 patients were analyzed; 84.8% received abobotulinumtoxin A with a mean dose of 599.7 ± 238.05 U; 7.93 ± 3.01 treatment cycles in 7.45 ± 4.25 muscles; and an average BoNT-A application of 120.3 ± 25.5 days. At baseline, 37.2% of patients stated that they were completely satisfied; meanwhile, at the end of the follow-up, the figure was 70.3%, suggesting an improvement on the rate of today’s satisfaction of 88.9%. The total baseline TWSTRS score was 40.2 ± 14.1, while at 3 years it was 23.2 ± 11.5, a tendency to decrease this score was observed registering a greater reduction, from −17.0, after 36 months. Conclusion: Results of this study suggest an improvement in the proportion of satisfied patients with CD treated with BoNT-A during a 36-month follow-up.