Exploration of the Upper Esophageal Sphincter Location in Healthy Individuals

Purpose: The behavior of the upper esophageal sphincter (UES) is a key component in studies of swallowing physiology. The UES rises during swallowing, secondary to traction from elevation of the hyolaryngeal complex. We aimed to describe patterns in UES position (i.e. height) across key time points during a swallow, while considering the effects of sex, age, and bolus consistency. Methods: Data were extracted from videofluoroscopies collected at 30 frames per second using 20% w/v barium in 76 healthy adults (37 males, 39 females), distributed across four age groups: 18–35, 36–53, 54–72, and 73–90 years. We analyzed 150 video clips: the first cup sip of thin liquid and the first teaspoon of mildly thick liquid for each participant. The vertebral section classifications (VERT) scale (Gao, 2023) was used to mark UES height (defined as the pit of the pyriform sinus), between the bottom of C7 and top of C3, with 3 segments per vertebrae and segments for each inter-vertebral space (IVS). We extended the scale to include C2, resulting in a scale with 23 levels (section 1 at the bottom of C7 and 23 at the top of C2). UES location was recorded at the following time points for each swallow: bolus passing mandible (BPM), UES opening (UESO) and closure (UESC), maximum UES height, and swallow rest (SR). Descriptive statistics were generated, and univariate analysis of variance was conducted to assess the effects of bolus consistency, sex, and age (α = .05).Results: Between BPM and UESC, the interquartile range for UES location spanned sections 13 to 17 on the VERT scale (bottom of C4 to bottom of C3). Prior to UESO, the UES was positioned one level higher with mildly thick liquids (level 14-15, i.e. mid to top C4) compared to thin liquids (level 13-14, i.e. bottom to mid C4) (p