Original ArticlesThree-Dimensional Stereophotogrammetry Assessment of Facial Asymmetry in Facial Palsyvan Veen, Martinus M. MD*; ten Berge, Joris H.A. BSc*; Werker, Paul M.N. MD, PhD*; Dijkstra, Pieter U. PT, PhD†,‡Author Information *University of Groningen, University Medical Centre Groningen, Department of Plastic Surgery †University of Groningen, University Medical Centre Groningen, Department of Oral and Maxillofacial Surgery ‡University of Groningen, University Medical Centre Groningen, Centre for Rehabilitation, Groningen, the Netherlands. Address correspondence and reprint requests to Martinus M. van Veen, MD, University Medical Centre Groningen, Department of Plastic Surgery, P.O. Box 30.001, NL-9700 RB Groningen; E-mail: email@example.com Received 15 August, 2019 Accepted 9 October, 2019 MMVV and JHATB contributed equally. The authors declare no conflicts of interest. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.jcraniofacialsurgery.com). Journal of Craniofacial Surgery: June 2020 - Volume 31 - Issue 4 - p 893-897 doi: 10.1097/SCS.0000000000006192 Buy SDC Metrics Abstract Three-dimensional stereophotogrammetry is not much used in assessing facial palsy and a comprehensive understanding of sources of variation in these measurements is lacking. The present study assessed intra- and interobserver reliability of a novel three-dimensional stereophotogrammetry measurement of facial asymmetry and examined sources of variation in these outcomes. Three photographs (rest, closed mouth smile, and maximum smile) were made of 60 participants, 30 facial palsy patients and 30 control subjects. All images were analyzed twice by 2 observers independently, to determine intra- and interobserver reliability. Variance component analysis was performed to investigate sources of variation in the outcomes. Intraobserver reliability was good with intraclass correlation coefficients ranging from 0.715 to 0.999. Interobserver reliability ranged from 0.442 to 0.929. Reliability of the smile image measurements was not clearly different from the rest images. Variation in measurement results was largely due to the status of a participant, facial palsy versus control. When splitting the sample, the facial expression was a major source of variation. Acceptable reliability of the proposed 3D facial asymmetry measurement was found, in facial palsy patients and control subjects. Interobserver reliability was marked less compared to intraobserver reliability. For follow-up data only one observer should assess 3D stereophotogrammetry measurements. © 2020 by Mutaz B. Habal, MD.