BotB (botulinum toxin type B): evaluation of safety and tolerability in botulinum toxin type A-resistant cervical dystonia patients (preliminary study).

Botulinum toxin (BTX) injection is considered the treatment of choice for patients with cervical dystonia (torticollis). We conducted a pilot, open-label, dose-escalation study with BTX type B in 12 patients who no longer responded clinically to injections with BTX type A. At the doses tested, BTX type B was safe and well tolerated without evidence of dose-limiting toxicity in this patient population. Mild-to-moderate adverse events generally resolved quickly and included asthenia, pain, nausea, dysphagia, hypertonia, and tremor. No serious adverse events or antibodies to type-B treatment were reported. Low-dosing-session (100-899 units) and high-dosing-session (900-1,500 units) groups were defined based on units administered per dosing session. Toronto Western Spasmodic Torticollis Rating Scale-Severity Scale (TWSTRS-Severity), Patient Analogue Pain Scale, and Physician and Patient Global Assessment Scales were measured during this study. The TWSTRS-Severity mean maximum percent improvement from baseline demonstrated a 9.9% versus 28.8% difference between the low-dose and high-dose groups, respectively. EFfectiveness was noted for the high-dose group on the Patient Analogue Pain Scale but not on the Global Assessment Scales.