Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Neurological disability
Systematic review	92 adults with cervical dystonia for at least 1 year and previously treated with botulinum A toxin, Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)-total score >20 and TWSTRS-severity >10 Data from 1 RCT	Improvement in TWSTRS-pain subscale 4 weeks 39/62 (63%) with botulinum B toxin (2500–5000 U) 25/30 (83%) with botulinum B toxin (10,000 U)	OR 0.39 95% CI 0.15 to 0.99 P = 0.05	Effect size not calculated	high-dose botulinum B toxin
Systematic review	92 adults with cervical dystonia for at least 1 year and previously treated with botulinum A toxin, TWSTRS-total score >20 and TWSTRS-severity >10 Data from 1 RCT	Improvement of at least 20% in TWSTRS-total score 4 weeks 37/62 (60%) with botulinum B toxin (2500–5000 U) 23/30 (77%) with botulinum B toxin (10,000 U)	OR 0.50 95% CI 0.20 to 1.25		Not significant
Systematic review	92 adults with cervical dystonia for at least 1 year and previously treated with botulinum A toxin, TWSTRS-total score >20 and TWSTRS-severity >10 Data from 1 RCT	Improvement of at least 20% in TWSTRS-total score 8 weeks 24/62 (39%) with botulinum B toxin (2500–5000 U) 16/30 (53%) with botulinum B toxin (10,000 U)	OR 0.56 95% CI 0.23 to 1.33		Not significant
Systematic review	92 adults with cervical dystonia for at least 1 year and previously treated with botulinum A toxin, TWSTRS-total score >20 and TWSTRS-severity >10 Data from 1 RCT	Improvement of at least 20% in TWSTRS-total score 12 weeks 14/62 (23%) with botulinum B toxin (2500–5000 U) 9/30 (30%) with botulinum B toxin (10,000 U)	OR 0.68 95% CI 0.25 to 1.84		Not significant
Systematic review	92 adults with cervical dystonia for at least 1 year and previously treated with botulinum A toxin, TWSTRS-total score >20 and TWSTRS-severity >10 Data from 1 RCT	Improvement of at least 20% in TWSTRS-total score 16 weeks 7/62 (11%) with botulinum B toxin (2500–5000 U) 5/30 (17%) with botulinum B toxin (10,000 U)	OR 0.63 95% CI 0.17 to 2.27		Not significant