The American Academy of Neurology (AAN) has announced updates to its 2008 guideline for botulinum toxin in the treatment of migraine headache, as well as 3 other conditions, adult spasticity, cervical dystonia, and blepharospasm. The updated guideline was published earlier this week in the online edition of Neurology®, and is scheduled for presentation at the AAN annual meeting in Vancouver. Four preparations of botulinum toxin are available in the United States, and they are not interchangeable. The guideline update assessed each formulation separately for each condition. Botulinum toxin blocks the release of substances at nerve endings, reducing muscle contraction and lessening the transmission of pain signals.
In the 2008 guideline, insufficient evidence was available to support a recommendation for botulinum toxin in the treatment of chronic migraine. Studies now support the effectiveness of onabotulinumtoxinA in reducing the frequency of migraine headaches, although the demonstrated benefit from the drug was small. In the 4 weeks after the first treatments, people had about 15 percent fewer days of headache compared with a placebo or dummy injection. For upper limb spasticity, the new guideline finds that three of the drug formulations—abobotulinumtoxinA, incobotulinumtoxinA, and onabotulinumtoxinA— are effective in reducing excess muscle tone and should be offered. For cervical dystonia, abobotulinumtoxinA and rimabotulinumtoxinB are effective and should be offered. Although research is less conclusive, the guideline states that nabotulinumtoxinA and incobotulinumtoxinA are probably effective for blepharospasm and should be considered. Read more about the AAN action here. The practice guideline is available here.