Botulinum toxin type A therapy for cervical dystonia.

Botulinum toxin type A therapy for cervical dystonia.

It is currently not possible to make definitive comparisons between BtA and BtB for the treatment of cervical dystonia; uncontrolled comparisons should be regarded with suspicion.

BackgroundThis is an update of a Cochrane Review, first published in 2005.Hemifacial spasm (HFS) is characterised by unilateral, involuntary contractions of the muscles innervated by the facial nerve. It is a chronic disorder, and spontaneous recovery is very rare. The two treatments routinely available are microvascular decompression and intramuscular injections with botulinum toxin type A (BtA). ObjectivesTo compare the e icacy, safety, and tolerability of BtA versus placebo in people with HFS. Search methodsWe searched CENTRAL, MEDLINE, Embase, reference lists of articles, and conference proceedings in July 2020. We ran the electronic database search, with no language restrictions, in July 2020. Selection criteriaDouble-blind, parallel, randomised, placebo-controlled trials (RCTs) of BtA versus placebo in adults with HFS. Data collection and analysisTwo review authors independently assessed records. We planned to select included studies, extract data using a paper pro forma, and evaluate the risk of bias. We resolved disagreements by consensus, or by consulting a third review author. We planned to perform metaanalyses. The primary e icacy outcome was HFS-specific improvement. The primary safety outcome was the proportion of participants with any adverse event. Main resultsWe found no parallel-group randomised controlled trials comparing BtA and placebo in HFS.

A single injection of BtB was effective and safe for treating cervical dystonia. Long-term uncontrolled studies suggested that further injection cycles continue to work for most patients. Future research should explore technical factors such as the optimum treatment intervals and use of image or electromyographic guidance for administration. Other issues include service delivery, quality of life, long-term efficacy and safety, and the relative indications for BtA, BtB and other treatments such as deep brain stimulation.