Botulinum toxin treatment failures in cervical dystonia: causes, management, and outcomes

Abstract

Botulinum toxin (BoNT) is highly effective in the treatment of cervical dystonia (CD), yet a significant proportion of patients report low levels of satisfaction following treatment and fail to follow-up for repeated treatments. The goal of this study was to determine the reasons some patients have unsatisfactory responses. A total of 35 subjects who came to our center requesting alternative treatments due to unsatisfactory responses following BoNT treatment for CD were evaluated. Included were 26 women and 9 men with an average age of 57.1 years (range, 25–82 years), and an average duration of illness of 12.5 years (range, 1–55 years). Details of unsatisfactory BoNT treatments were methodically collected by a movement specialist using a standardized intake form, including provider subspecialty, product used, number of satisfactory or unsatisfactory trials, doses given, specific muscles treated, use of electromyographic guidance, side effects, and tests of resistance. The specialist then provided repeat treatments if indicated, and followed each case until the reasons for unsatisfactory outcomes could be determined. Multiple reasons for unsatisfactory outcomes were found. They included suboptimal BoNT doses, suboptimal muscle targeting, intolerable side effects, complex movement patterns, discordant perceptions, and incorrect diagnoses. Only 1 patient was functionally resistant to BoNT. Of 32 subjects who received repeat BoNT treatments, 25 (78%) achieved satisfactory responses after revision of the original treatment plan. These results indicate that the majority of unsatisfactory responses to BoNT treatment of CD were caused by correctible factors and imply a need for improved education regarding optimal treatment methods.

The role of polymyography in the treatment of cervical dystonia

“…As mentioned above, up to 78 % of patients receiving repeated injections had satisfactory responses following a mean number of 2 trials [1]. However, this could range from 1 to 8 trials [1].…”

“…They found that unsatisfactory outcomes were largely driven by suboptimal BoNT doses, wrong muscle targeting, and/or complex movement patterns [1]. Only one patient was functionally resistant to BoNT [1]. Notably, the majority of patients (about 78 %) receiving repeated injections reached a satisfactory response after adjusting BoNT dosing and/or muscle targets, indicating the final outcomes crucially relied on the involved physicians' expertise [2].…”

“…They found that unsatisfactory outcomes were largely driven by suboptimal BoNT doses, wrong muscle targeting, and/or complex movement patterns [1]. Only one patient was functionally resistant to BoNT [1].…”

“…We commend Dr. Jinnah and colleagues for evaluating the reasons for unsatisfactory response to botulinum toxin (BoNT) in 35 patients with cervical dystonia (CD) [1]. They found that unsatisfactory outcomes were largely driven by suboptimal BoNT doses, wrong muscle targeting, and/or complex movement patterns [1].…”

How Effective and Safe is Botulinum Toxin Therapy in Cervical Dystonia: The Current Stand

“…Common determinants for an unsuccessful chemodenervation session/poor responder include suboptimal doses, suboptimal muscle targeting, intolerable side efects, and complex movement paterns, discordant expectations, and an incorrect diagnosis [46].…”