What is the efficacy of botulinum toxin (BoNT) in the treatment of focal dystonias?

Updated: Oct 10, 2019
  • Author: Divakara Kedlaya, MBBS; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Use of BoNT-A in different types of focal dystonias has been well studied and has proven to be very effective. Botulinum toxin injection is the treatment of choice for cervical dystonia (spasmodic torticollis). [15, 16, 88] . A Cochrane review concluded that a single injection of BoNT-B was effective and safe for treating cervical dystonia. [89] This injection benefits the highest percentage of patients in the shortest time and has been proven effective in many double-blind, placebo-controlled trials.

BoNT has fewer side effects than do other pharmacologic treatments. The efficacy and safety of BoNT injections for the treatment of certain movement disorders, including blepharospasm, hemifacial spasm, oromandibular dystonia, cervical dystonia, focal limb dystonias, laryngeal dystonia, tics, and essential tremor is ongoing. [90]

In a double-blind, placebo-controlled trial by Greene and colleagues, 55 patients who previously had failed to find relief in 2 trials of medication received either BoNT or placebo in a double-blinded fashion and were tracked for 12 weeks. [91] Four weeks of open phase then followed when all patients received BoNT. By 6 weeks, 61% of patients showed improvement in head posture, and 39.5% reported reduction of pain. Both measures significantly improved (P< .05) compared to controls. During the open phase, patients who previously received placebo exhibited a similar response. Overall, 74% of patients improved by the end of the study.

A study by Brans and colleagues showed that in 64 patients with cervical dystonia, 84% reported long-term benefits in terms of impairment, disability, handicap, and quality of life (QOL). [92] Mezaki et all described their experience with a Japanese type A toxin for the treatment of cervical and axial dystonias. [93] Injections were given repeatedly at intervals of 28-30 days to carefully chosen muscles with increased activities, with a maximum dose per session of 300 units. The maximum improvements in subjective and objective ratings were obtained only after repeated injections.

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