UBC Theses and Dissertations
Quantitative analysis of oral phase dysphagia Lee, Chae-Joon
Swallowing disorders (dysphagia) are becoming increasingly prevalent in the health care field. Oral phase dysphagia specifically refers to swallowing difficulties encountered during the initial, voluntary segment of the swallowing process, where the ingested food material is prepared into a manageable food mass (bolus) and then propelled from the mouth to the pharynx. Proper management (evaluation and treatment) of oral phase dysphagia poses a difficult task. The swallowing process is a complex sequence of highly coordinated events, while oral phase dysphagia can originate from a wide range of underlying causes. From a review of the literature, it is apparent that much of the current methods of management for oral phase dysphagia rely much on the subjective skills of the clinician in charge. In order to improve upon these methods as well as to gain a better understanding of the swallowing mechanism, the development of new, quantitative clinical methods are proposed. A computer-aided tongue force measurement system has been developed that is capable of quantifying individual tongue strength and coordination. This strain gauge-based transducer system measures upward and lateral tongue thrust levels during a "non-swallowing" test condition. Clinical testing has been performed on 15 able-bodied control subjects with no prior history of swallowing difficulty and several patient groups (25 post-polio, 8 stroke, 2 other neuromuscular disorders) with or without swallowing difficulties. The results have demonstrated the system's potential as a reliable, clinical tool (repeatability: t-test, p < 0.01) to quantify variation in tongue strength and coordination between and within the control and patient groups. In order to investigate the possible existence and role of a suction mechanism in transporting the bolus during the oral phase, a pharyngeal manometry setup has been utilized for oral phase application. This novel approach (oral phase manometry) would determine whether the widely-accepted tongue pressure mechanism is solely responsible for oral phase bolus transport. Based on extensive manometric data obtained from an able-bodied subject without any swallowing abnormality, no significant negative pressure or pressure gradients (suction) were found during the oral phase. The pressure generated by the tongue acting against the palate in propelling the bolus during the oral phase has been utilized in the development of an oral cavity pressure transducer system. This computer-aided measurement system employs a network of ten force sensing resistors (FSR's) attached to a custom-made mouthguard transducer unit to record the wave-like palatal pressure pattern during an actual swallow. Clinical testing has been performed on 3 able-bodied subjects with no swallowing abnormality, and their pressure data have been found to support tbe reliability of the device (repeatability: t-test, p < 0.01). The system has also been applied to study the effects of bolus size and consistency on the palatal pressure pattern during the oral phase. The results of this investigation has confirmed the importance of the tongue during the oral phase of swallowing. It has been shown that deficiency in tongue strength or coordination is a primary factor in oral phase dysphagia. The new, quantitative clinical methods which were developed for this research has utilized these parameters to provide improved methods of evaluation and treatment for oral phase dysphagia.