Objective: To update a Cochrane review comparing botulinum neurotoxin type A (BtA) to placebo in adults with hemifacial spasm (HFS).

Background: This is an update of a previous Cochrane systematic review (Costa 2005). Hemifacial spasm is characterized by unilateral involuntary contractions of the muscles innervated by the facial nerve, and although benign, it can cause significant cosmetic and functional disability. The two treatments routinely available are microvascular decompression and BtA.

Methods: Search Methods: Cochrane Movement Disorders Group trials register, CENTRAL, MEDLINE, EMBASE, as well as reference lists of articles and conference proceedings, last run in December 2015. Selection criteria: double-blind, parallel, randomized, placebo-controlled trials of BtA in adult patients with HFS. Data collection: two independent authors assessed records, selected included studies, extracted data and evaluated the risk of bias. Disagreements were solved by consensus or by a third element.

Results: We included 1 study (n=11) with a moderate-to-high risk of bias. [figure1] BtA-treated patients showed a high likelihood of improving, both based on patient (OR 15.09, 95%CI 6.42 to 35.48) and clinical (OR 7.16, 95%CI 2.79 to 18.37) assessments. A dose-dependent response was not appreciated in the BtA arm. Adverse events were very frequent but it was not possible to compare treatment arms. One patient drop-out from the study due to facial weakness.

Conclusions: Very low quality evidence showed BtA is effective for HFS. The findings of this update provide the best evidence currently available, but also reveal areas of uncertainty that should be addressed in future research. Further studies should also consider recruiting much larger samples and address questions such as the safety profile of BtA, the impact of Bt on quality of life, subgroup analysis of treatment naïve patients versus subjects previously treated microvascular decompression, and idiopathic versus compressive versus postparalytic HFS.

Costa J, Espírito-Santo CC, Borges AA, Ferreira J, Coelho MM, Moore P, Sampaio C, Duarte G, Rodrigues F, Castelão M, Marques AR. Botulinum toxin type A therapy for hemifacial spasm. Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD004899. DOI: 10.1002/14651858.CD004899.pub2.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/botulinum-neurotoxin-type-a-versus-placebo-for-hemifacial-spasm-in-adults-2016-cochrane-movement-disorders-group-systematic-review-update/