Effective converting ratio when switching between Ona-botulinumtoxin-A and Abo-botulinumtoxin-A in cervical dystonia. A patient assessment cross over study

Abstract

Background and Purpose: Due to ongoing debate and lack of data, the aim of this study was to determine an effective conversion ratio between Ona-botulinum toxin-A / Abo-botulinum toxin-A therapy. Methods: This study includes patients with cervical dystonia who obtained a satisfying improvement to Ona-botulinum toxin-A and respectively Abo-botulinumtoxin-A injections. The patient´s satisfaction of the procedure was measured as effect on a VAS-score (0-100%). Data was usable in our study when each patient reached a satisfying improvement of minimum 90% after toxin treatment. Toxins were injected in the same muscles, using the same technique every 3rd month. EMG was used to measure the dystonic activity in the muscles in the cervical region. The average conversion ratio of Ona-botulinum toxin-A/Abo-botulinum toxin-A was estimated when stable optimal treatment doses were found (VAS-score outcome of 90%). Results: 48 patients with cervical dystonia had a treatment time of 15,75±4,58 years. We sampled 2546 injection series. Doses were 126 ± 38,77 U for Ona-botulinumtoxin-A and 381,6 ± 151,1 U for Abo-botulinumtoxin-A. The VAS-score was found to be between 90-100% either using Ona or Abo-botulinum toxin-A. Conclusion: A conversion ratio of 1: 2,56 was safe and satisfying when changing treatment between Ona-botulinumtoxin-A to Abo-botulinumtoxin-A.