Interesting ImagesThe Monocle Sign in FDG-PET A Sign of Contralateral Facial Nerve PalsyOrita, Erika MD, PhD∗; Meerwein, Christian M. MD†; Pizzuto, Daniele A. MD∗; Stolzmann, Paul MD∗; Huellner, Martin W. MD∗Author Information From the ∗Departments of Nuclear Medicine †Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich/University of Zurich, Zurich Switzerland. Received for publication May 21, 2019; revision accepted July 21, 2019. Conflicts of interest and sources of funding: none declared. Correspondence to: Erika Orita, MD, PhD, Department of Nuclear Medicine, University Hospital Zurich/University of Zurich, Rämistrasse 100, 8091 Zurich, Switzerland. E-mail: [email protected]. Clinical Nuclear Medicine: February 2020 - Volume 45 - Issue 2 - p e94-e95 doi: 10.1097/RLU.0000000000002787 Buy Metrics Abstract We report three cases of unilateral 18F-FDG uptake in the orbicularis oculi muscle in subjects with contralateral peripheral facial nerve palsy. We argue that this asymmetric uptake pattern in fact reflects lack of metabolism on the side affected by facial nerve palsy, owing to denervation. Since the unilateral periorbital uptake resembles a monocle, we chose to call this finding the monocle sign. The monocle sign should not be confused with inflammation or tumor, but should prompt a neurological assessment for facial nerve palsy and a potential underlying disease. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.