Patient perspectives on the therapeutic profile of botulinum neurotoxin type A in cervical dystonia

Abstract

Background Botulinum neurotoxin type A (BoNT-A) is an effective pharmacological treatment for the management of cervical dystonia (CD) that requires repeated administration at variable intervals. We explored patient perceptions of the impact of CD and the waning of BoNT-A therapeutic effects. Methods An internet-based survey was conducted through Carenity, a global online patient community, from May to September 2019. Eligible respondents were adults with CD who had ≥ 2 previous BoNT-A injections. Results 209 respondents (81% females; mean age of 49.7 years) met the screening criteria. The mean BoNT-A injection frequency was 3.9 injections/year. The mean reported onset of BoNT-A therapeutic effect was 11.7 days and the time to peak effect was 4.5 weeks. Symptom re-emergence between injections was common (88%); the time from injection to symptom re-emergence was 73.6 days (~ 10.5 weeks). Treatment was not reported to completely abolish symptoms, even at peak effect. However, symptom severity was rated (0 = no symptoms; 10 = very strong symptoms) as lowest at the peak of treatment effects (mean scores ~ 3/10), increasing as the effects of treatment start waning (~ 5.5/10) and was strongest one day before the next session (~ 7–8/10). The impact of CD on quality of life followed the same ‘rollercoaster’ pattern. Conclusions This survey highlights the burden of CD symptoms, even in patients undergoing regular treatment. Symptom re-emergence is common and has significant impact on daily activities and quality of life. Greater awareness of the therapeutic profile of BoNT-A treatment should lead to better informed therapeutic discussions and planning.

Botulinum Toxin in Movement Disorders: An Update

“…Common causes of BoNT discontinuation in CD is lack of response, short duration of benefit, side effects, inconvenience, and cost [ 123 , 124 ]. In one survey, of 209 respondents, the mean reported onset of BoNT-A therapeutic effect was 11.7 days and the time to peak effect was 4.5 weeks; the time from injection to symptom re-emergence was 73.6 days (~10.5 weeks); 88% experienced symptom re-emergence between injections [ 125 ]. Therefore, developing new BoNT preparations with longer duration of action is one of the highest priorities in experimental therapeutics of dystonia.…”

Pain in cervical dystonia: mechanisms, assessment and treatment

“…There is clearly a difference in the symptom relief achieved at peak BoNT-A effect (assessed at Week 4) versus across the injection cycle and clinicians are typically more interested in how well symptoms, including pain, are covered in between dosing sessions. In a recent survey of CD patients treated with BoNT-A (all formulations), pain was often the first symptom to reappear between doses and the mean time to the patients noticing waning of BoNT-A effects was 10.5 weeks suggesting that many patients have to live with significant symptom reemergence for at least a few weeks before they are reinjected [14]. Residual pain has also been identified as a predictor of non-satisfaction with long-term BoNT-A [75].…”

“…When present, pain is a major contributor to disability [9,10] and social isolation [11], and is often the main reason patients seek treatment for CD [12,13]. Surveys evaluating patient perceptions of their CD symptoms consistently highlight pain as a troublesome and disabling feature of their condition with significant impact on daily life and work [14,15]. However, while pain has long been recognized as a core feature of CD, its phenomenology is not well understood.…”

Botulinum neurotoxin in cervical dystonia revisited — recent advances and unanswered questions

“…So-called booster injections (it was a common practice in the early years to inject patients with an additional dose after several weeks) have been identified as the chief culprit of antibody formation and secondary nonresponsiveness. Many patients have a shorter beneficial period (mean 10.5 weeks in 88% of patients) [42], and therefore physicians are tempted to inject earlier. They may be encouraged by no reports on antibody formulation after new BoNT/A preparation without complexing proteins (INCO-BoNT/A) [43].…”