Dose per muscle in cervical dystonia: pooled data from seven movement disorder centres

Aim of the study. Botulinum neurotoxin type-A (BoNT/A) injections are the established treatment in cervical dystonia (CD). But clinical practice regarding the choice of muscles into which injections are made varies between centres. Until now, there have been no dose-per-muscle recommendations based on `searching the dose' clinical trial data. Clinical rationale for study. We therefore examined the dosages under real world conditions at seven international movement disorders centres, using an identical clinical approach. Results. We examined 305 patients with CD (55.6 +/- 13.2 years, 204 female). The most commonly injected muscles were the splenius capitis (84.9%), sternocleidomastoid (80.3%), trapezius (59.7%), levator scapulae (49.8%), semispinalis capitis (39%), and obliquus capitis inferior (36.7%). The mean total dose per treatment session with aboBoNT/A was 652.5 (SD = 285.5), with onaBoNT/A it was 159.5 (SD = 62.4), and with incoBoNT/A it was 173.4 (SD = 99.2) units. The doses injected into each muscle in the ona- or incoBoNT/A groups were between 19.7 and 48.2 units, with the highest dose for the splenius capitis with 49.2 +/- 26.0 units. The doses in the aboBoNT/A group were between 69.6 and 146.4 units, and the highest dose being injected into the splenius capitis (139.6 +/- 80.7 units). Conclusions and clinical implications. In clinical trials the doses per muscle are based on an arbitrary decision. In our study, the doses were lower than in other studies, which may be due to the number of muscles per session, the use of ultrasound guidance (and therefore more precise injections), as well as the use of the Col-Cap concept. Our results exemplify everyday practice, and may help as the basis for recommendations and further investigations.