Reliability of Ultrasound Examination of Hyoid Bone Displacement Amplitude: A Systematic Review and Meta-Analysis

In swallowing, the hyoid bone moves up and forward in response to the activation of suprahyoid muscles, opening the upper esophageal sphincter and aiding the airway protection mechanism. This displacement measure has been analyzed with ultrasound images because this method does not expose the patient to radiation, has a good cost-benefit ratio, and is safe for the patient. However, there is no consensus on the reliability of this ultrasound measure. The objective of this study was to analyze the reliability of measuring hyoid bone displacement amplitude in swallowing with ultrasound. The systematic review encompassed five databases (MEDLINE, Scopus, EMBASE, Web of Science, Cochrane Library) and gray literature. There was no limitation of language or year of publication. The search/selection/extraction methodology was conducted by two authors blindly and independently, and differences were solved by a third rater. Three studies met the eligibility criteria: two of them analyzed the reliability in non-dysphagic populations and the other, in dysphagic patients. The transducer was positioned in the submandibular region in all studies. The authors were not clear about the training time to acquire and analyze ultrasound images. The meta-analysis had an interrater reliability of 0.858 (95% CI: 0.744-0.924) and intrarater reliability of 0.968 (95% CI: 0.903-0.990). There was, however, heterogeneity of p = 0.005 for intrarater reliability. Despite good reliability, the heterogeneity reinforces the importance of training and protocol standardization for image acquisition and analysis.