Development of a System to Monitor Laryngeal Movement during Swallowing Using a Bend Sensor

Abstract

BackgroundSwallowing dysfunction (also known as dysphagia), which results in a deterioration of nutritional intake, slows rehabilitation and causes aspiration pneumonia, is very common following neurological impairments. Although videofluorographic (VF) examination is widely used for detecting aspiration, an objective and non-invasive method for assessing swallowing function has yet to be established because of a lack of adequate devices and protocols. In this paper, a bend sensor whose resistance is altered by bending was introduced to monitor swallowing-related laryngeal movement.MethodsSix healthy male volunteers were recruited in the present study. Specific time points on the signal waveform produced by the bend sensor were defined to describe laryngeal movement by differential analysis. Additionally, the physiological significance of the obtained waveform was confirmed by analyzing the sequential correlations between the signal waveform from the bend sensor and hyoid bone kinetics simultaneously recorded by VF.ResultsSeven time points were successfully defined on the signal waveform to reference laryngeal movement. Each time point was well correlated with certain VF events, with evidence of no significant time lags, and there were positive correlations between waveform time points and matched VF events. Furthermore, obvious similarities were noticed between the duration of each phase on the signal waveform and the duration of the matched hyoid bone activity.ConclusionsThe present monitoring system using a bend sensor might be useful for observing the temporal aspects of laryngeal movement during swallowing, and it was well coordinated with hyoid bone movement.

Coordination in oro-pharyngeal biomechanics during human swallowing

“…1B) which could bend physically with motion [16]. An increasing bend angle is generally associated with increased measured resistance.…”

“…After fixing it along the midline of the frontal neck with its tip at the level of the prominence of the thyroid cartilage when reaching the highest position during swallowing (Fig. 1D), the hyoid activity could be determined noninvasively from the produced signal waveform [16]. The swallowing sound is bilaterally symmetric [19], so we placed one microphone (JM-0116, Ono-Sokki, Tokyo, Japan) ( Fig.…”

“…Specifically, the time points on the signal waveform were defined as references for describing the state of laryngeal movement, and they were base on the change in magnitude and direction of velocity and smoothed acceleration signals that could be obtained by first-order differentiation and averaging 50 sequential second-order differentiated values of the original signal, respectively. The time points T3 and T7 were not counted in the present study because of their meaninglessness for presuming the swallowing-related hyoid motion [16]. Consequently, according to our previous report [16], the laryngeal signal waveform was subdivided into four phases which were shown in Table 2.…”

“…The time points T3 and T7 were not counted in the present study because of their meaninglessness for presuming the swallowing-related hyoid motion [16]. Consequently, according to our previous report [16], the laryngeal signal waveform was subdivided into four phases which were shown in Table 2. The duration of each phase was calculated.…”

“…In addition to a sensor sheet system for assessing the oral stage of swallowing, a bend sensor system that is useful for obtaining the temporal aspects of laryngeal movement synchronized with hyoid motion during swallowing was also established successfully [16]. The objective of the present study was to investigate the sequential coordination between the tongue pressure production and hyoid-laryngeal movement using the two noninvasive sensing systems, which were expected to act as a comprehensive system to evaluate the oral and pharyngeal stages of swallowing.…”