ORIGINAL ARTICLE The Mendelsohn Maneuver and its Effects on Swallowing: Kinematic Analysis in Three Dimensions Using Dynamic Area Detector CT Yoko Inamoto 1,2 • Eiichi Saitoh 2 • Yuriko Ito 2 • Hitoshi Kagaya 2 • Yoichiro Aoyagi 2 • Seiko Shibata 2 • Kikuo Ota 2 • Naoko Fujii 3 • Jeffrey B. Palmer 4 Received: 16 July 2017 / Accepted: 4 December 2017 Ó Springer Science+Business Media, LLC, part of Springer Nature 2017 Abstract This study investigated the effects of Mendelsohn maneuver with three-dimensional kinematic analysis. Nine female speech-language pathologists (nine females, mean ± SD 27.1 ± 3.5 years old) underwent 320-row area detector scan during swallows of 4-ml nectar-thick liquid using with no maneuvers (control) and with Mendelsohn maneuver (MM). Critical event timing (hyoid, soft palate, epiglottis, laryngeal vestibule, true vocal cords (TVC), UES), hyoid and laryngeal excursion, cross-sectional area of UES, and volume of pharyngeal cavity and bolus were measured and compared between two swallows. In MM, all the events were significantly prolonged with delayed termination time (p \ 0.05) except UES opening. The onset, termination, and duration of UES opening were not significantly affected by MM nor was timing of bolus transport. The hyoid bone was positioned significantly higher at maximum displacement (p = 0.011). Pharyngeal constriction ratio was 95.1% in control and 100% of all subjects in MM. Duration of minimum pharyngeal volume was significantly longer in MM than in control (p = 0.007). The MM produces several distinct changes in the kinematics of swallowing in healthy subjects with no dysphagia. The changes in the timing and magnitude of hyoid displacements and prolonged closure of the pharynx during swallowing suggest the utility of MM for improving the safety and efficiency of swallowing in selected cases. Keywords Deglutition Á Deglutition disorders Á Rehabilitation Á Pharyngeal muscles Á Upper esophageal sphincter Á Mendelsohn maneuver Á Multidetector computed tomography Introduction Swallowing is a set of motor behaviors that is precisely coordinated, but also adaptable depending on sensory inputs and volition. Swallowing maneuvers are techniques which alter specific components of swallow physiology under voluntary control [1, 2] and, in case of dysphagia, can modify the swallow to improve its safety and effi- ciency. The Mendelsohn maneuver (MM) is designed to enhance opening of the upper esophageal sphincter (UES) by volitional increase in the duration of submental muscle contraction during the swallow. It is a well-known maneuver and is often used in clinic setting; however, its physiology has not been completely established. The Mendelsohn maneuver is commonly understood to increase the extent and duration of laryngeal elevation and thereby increase the duration and width of UES opening [2–4]. The primary mechanism for UES opening is traction from the suprahyoid and infrahyoid musculature that pulls the sphincter open [5–7]. Thus, this maneuver is thought to be effective for those who have insufficient UES opening because of decreased laryngeal elevation [8]; this has been validated in dysphagic patients with a decrease of aspira- tion and pharyngeal residue [3, 4, 9]. This effect on UES & Yoko Inamoto inamoto@fujita-hu.ac.jjp 1 Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, Japan 2 Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan 3 Department of Radiology, School of Medicine, Fujita Health University, Toyoake, Japan 4 Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, USA 123 Dysphagia https://doi.org/10.1007/s00455-017-9870-7