A 10-year service evaluation of a Cervical Dystonia Botulinum Toxin A Clinic: factors associated with patient-reported outcomes.

Background: The efficacy and safety of botulinum toxin A (BoNT-A) has been well established for cervical dystonia (CD). In clinical practice, individual injection schemes vary widely.

Aims: To examine patient satisfaction of routine care with BoNT-A for CD in a "real-world" clinical setting.

Methods: Patients with primary CD attending a specialist botulinum toxin clinic were evaluated over a 10-year period (2008-2018). At each clinic visit, patients were asked to complete a questionnaire with a visual analogue score between 0 and 100 to rate their response from the previous injection. Outcomes were recorded as static measurements of the time to reach 50% improvement and 75% improvement. The association between patient factors and outcome were assessed using Fisher exact test and standard t test.

Results: Data was recorded for 135 patients attending for 1665 injections over a 10-year period. Overall, 84% of patients achieved 50% improvement (n = 114) and 73% (n = 99) achieved 75% improvement. There was no significant association between gender, head tremor, toxin preparation or head posture with either the likelihood of achieving 50% improvement or the time to achieve 50% improvement. A sensory trick was reported in 82% (n = 111). Those who did not have a sensory trick were more likely to have reported a preceding trauma (62% vs 18%, p = 0.05) and were less likely to achieve 50% improvement.

Conclusion: BoNT-A was shown to be safe and effective for CD. The absence of a sensory trick was associated with less response to BoNT-A. Other factors did not show a clear association.