Test Instrument, Bolus size, Multiple Swallows and Ultrasound in the Evaluation of Oral-Stage Swallow

A previous study identified a subset of participants who required multiple swallows to clear a single bolus (Weinhold & McKay, 2017). Presence of multiple swallows was positively correlated with orofacial myofunctional disorder (OMD), suggesting that multiple swallows might be a potential screening marker for OMD. Since bolus size was not controlled in the study, reviewers questioned whether multiple swallows might have been a consequence of larger bolus size. In 2018, Pennington and Weinhold replicated this study by using a consistent 5ml bolus and revealed a similar correlation between OMD and multiple swallows. However, the test instrument used in that study to identify OMD yielded an OMD incidence of 60%. Accordingly, a new test instrument was developed to increase specificity of scoring for future studies. The new instrument identified 30% of participants as having OMD, which is more in line with the literature. The current study replicated Weinhold & McKay (2017) by utilizing the new test instrument as well as a predetermined average sip size for each participant. Utilizing both a controlled bolus of 5ml, and a participant-specific bolus size failed to eliminate multiple swallows. Linear regression revealed no significant relationship between size of bolus and number of swallows for either study; therefore, the hypothesis that the size of the unmeasured boluses in Weinhold & McKay caused differences in number of swallows was rejected. The suggestion that multiple swallows are indicative of OMD was strengthened, prompting further investigation into the relationship between number of swallows per bolus and OMD. Ultrasound images of three stages of the oral swallow were compared for the OMD and non-OMD groups. No statistical differences were noted in tongue constriction, which did not support our hypothesis that the OMD participants would display less constriction. However, baseline tongue position of /𝑎/ for participants with OMD was significantly lower than the baseline of participants without OMD. Pertinence of these findings relative to the oral stages of the swallow are addressed, as well as implications of oral stage dysfunction in general.