Physical therapy for facial nerve paralysis (Bell's palsy): An updated and extended systematic review of the evidence for facial exercise therapy.

"Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article."

"Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by the National Institute for Health Research (NIHR) as part of FRAME project (Reference Number II-LA-0814-20008)."

"The review aimed to identify and assess recent evidence of the effectiveness of facial exercise therapy, draw out any clinically relevant findings, and identify future research needs. The review protocol was submitted for peer-review to the International Prospective Register of Systematic Reviews (PROSPERO), ID: CRD42017073067. A mixed-methods approach to evidence synthesis was specified in the protocol to allow for the inclusion of different study designs, in addition to randomised controlled trials., The peer-reviewed protocol also specified the inclusion of evidence from post-2011 reviews to maximise the evidence identified. There was strict adherence to international guidelines on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Methods: Predetermined inclusion/exclusion criteria were utilised to shortlist abstracts. Two reviewers independently appraised articles, systematically extracted data and assessed the quality of individual studies and reviews (using GRADE and AMSTAR-2, respectively). Thematic analysis used for evidence synthesis; no quantitative meta-analysis conducted. The review was registered with PROSPERO (CRD42017073067)."