| Swallowing refers to the entire act of placement of food in the mouth followed by theoral, pharyngeal and esophageal phases until the entrance of food into the stomach. As oneof the most complex physical behaviors requiring coordinated actions of several structures, it is modulated by the brainstem swallowing center, with the oral phase under voluntaryneuromuscular control and the latter two phases under involuntary neuromuscular control.First, the ingested food is processed to a bolus with adequate properties after masticationfollowed by the posterior propulsion with the help of tongue-hard palate contact (tonguepressure). Then, the swallowing is triggered with sensory input from receptors in thepharyngeal region as soon as the bolus reaches the pharynx, during which a continuum ofevents occurred in a well-defined tune, including vertical and anterior displacement of thehyolaryngeal complex, tilt and seal of the epiglottis, closure of the true and false vocalfolds, and opening of the upper esophageal sphincter (UES). Subsequently, the bolus istransferred down the throat into the esophagus safely, before peristaltic waves finally carryit from the esophagus to the stomach. Normal swallowing function plays a crucial role infood transportation, human nutrition, physical growth and even survival. Any disorderedactivities of the above structures and disrupted coordinated movements may result indysphagia which harms the health or even makes a threat to life.Swallowing disorder is the consequences of various diseases, such as stroke,Parkinson’s disease, Alzheimer’s disease, hemiplegia, myasthenia gravis and so on. It hasbecome a matter of increasing concern in the modern medicine. The specialists fromneurology department, E.N.T. department and rehabilitation department began to paymore and more attention to evaluate swallowing function and treat dysphagia. Also, in thedental practice, dentition defect, edentulous jaw, cleft lip and palate as well asmaxillofacial truama and tumors could result into reduced masticatory efficiency,velopharyngeal insufficiency, oral maxillofacial deformity or disorded motion of tongueand hyoid, which make lots of patients suffer from dysphagia. Therefore, it is ofimportance for dentist to take swallowing function evaluation into consideration before,during and after the diagnosis and treatment of common oral diseases, as this issue is vitalfor patients’ oral function rehabilitation. Thus, applying the appropriate appliances toevaluate the swallowing function and early diagnose dysphagia in dental work will notonly reduce the intensity of clinical work and improve the quality of health care, but alsobe helpful to reduce the patients’ sufferings and improve their quality of life. Clinically, several methods have been adapted to measure swallowing function,including videofluorography (VF), videoendoscopy (VE), magnatic resonance imaing(MRI), computed tomography (CT), ultrasonography (US) and electromyography (EMG).Among them, VF is considered as the golden standard. There is no denying that all theabove methods have helped us to better understand swallowing physiology and providedus important reference data and clinical value. Nevertheless, their disadvantages also limittheir application widely because of the radiation exposure during observation, thecomplexity of the equipments operation, the high cost of physical examination or theinconvenience to medically unstable patients. The performances of them could trouble thedysphagic patients and give rise to ethical concerns sometimes.Physically, dysphagia could attibute to the abnormal function of certain structures ororgans in the oral cavity and pharynx after some stomatology disease. Moreover, the cureof oral disease is not only limited to the recovery of physiological structure. Itscoincidence with the recovery of physiological function has become an inevitable trend ofthe modern oral and dental sciences. Consequently, it is the dentists’ duty to carry out theswallowing function evaluation during the treatment of oral diseases as well as earlydiagnosis and treatment of dysphagia arise from oral diseases. In these contexts, thedevelopment of a simple, non-invasive and quantitative method to assess theswallow-related organs is currently one of the most important issues.Our previous research has successfully developed a sensor sheet for measuringtongue pressure produced by tongue-hard palate contact during swallowing. In thisresearch, we will introduce a bend sensor which is used for fine motor analysis of limb inthe rehabilitation field to observe the hyolaryngeal excursion during swallowing. Afterconfirmation of the best position to attach the bend sensor on the neck and thedetermination of several time points as well as the characters of the produced signalwaveform, the efficiency of bend sensor to detect laryngeal movement was verified byanalyzing the correlations and coordinations between time points on the signal waveformand hyoid activities acquired via VF. Then, tongue pressure sensor sheet and bend sensorwere applied simultaneously to determine the coordination of tongue pressure production and hyoid movement during swallowing in healthy subjects. It will benefit the evaluationof swallowing function non-invasively, simply, efficiently and quantitively. In addition,the bio-sensing system used in the present study provides the clinicians clinical trialsupport to diagnosis and treat dysphagic patients chair-side and bed-side.The research is composed of two parts as listed below:Part1, Validation of the efficiency of bend sensor to monitor laryngealmovement during swallowing.First, twelve adult male subjects were recruited in this study for confirming the bestposition for attaching the bend sensor. Three positions on the front of the neck were testedto identify the best position to attach the bend sensor during swallowing5ml of water.Although the frequency of similar wave patterns among3positions differed little with nosignificant difference, the produced waveform was simple, clear and convenient for lateranalysis, and the maximum amplitude of the waveform was much larger when the tip ofthe sensor was fixed to the skin at the level of the prominence of the thyroid cartilagewhen it reaches highest position during swallowing. Consequently, the suitable positionfor placing the bend sensor was determined. In addition, the characters of the producedwaveform were described particularly based on7time points which were defined bydifferentiation.Then, in order to evaluate the physiological significance of the waveform producedby the bend sensor during swallowing, six adult male subjects were recruited, and the tipof the bend sensor was fixed to the skin at the level of the prominence of the thyroidcartilage when it reaches highest position during swallowing5ml of liquid barium bolus.In addition, VF was used to observe the hyoid motion simultaneously. The results showedus that the time lags between certain time points of the obtained waveform from bendsensor and certain hyoid activities observed by VF were negligible with positivecorrelations indicating that we could presume some important hyoid activities by certaintime points of the waveform from bend sensor during swallowing. Furthermore, therewere no obvious significances after comparing each phase on the signal waveform and the VF events.Part2, Application of the biosensor in the study of the coordination of tonguepressure production and hyoid movement during swallowing.Fourteen adult male subjects were recruited in this study to observe the pattern oftongue pressure (TP) during swallowing. The pattern of TP produced in five contactsbetween the tongue and hard palate during swallowing5ml of water was recorded by atongue pressure sensor sheet. TP was generated initially by close contact with theanteriomedian part of the hard palate, then with the circumferential part, and finally withthe posteriomedian part. TP reached a peak quickly, then decreased gradually beforedisappearing almost simultaneously at each measured part of the hard palate. Duration,magnitude and integrated value of TP were significantly smaller in the posteriomedian partcompared to the other four parts measured. No laterality was found in TP produced at thecircumferential parts of the hard palate. Our findings indicate that the order of tonguecontact against each part of the hard palate as well as duration and magnitude of TP arecoordinated precisely during swallowing.Then, twelve adult male subjects were recruited for investigating the influence ofusage of tongue pressure sensor sheet on the signal waveform produced by bend sensorduring swallowing. The data recorded by bend sensor was obtained with attaching tonguepressure sensor sheet simultaneously or not during swallowing5ml of water. There wereno obvious significances for the time lags between the same time point or for the matchedphases on the signal waveform produced by bend sensor whether concurrently attachingtongue pressure sensor sheet or not, suggesting us that the usage of tongue pressure sensorsheet exerted no influences on the waveform of the laryngeal movement produced by bendsensor during swallowing.At last, fourteen adult male subjects were recruited to measure the coordinationtongue pressure and hyoid movement with sensors during swallowing. In this study, weapplied a tongue pressure sensor sheet on the hard palate to record TP and a bend sensoron the frontal neck to monitor the laryngeal movement which was synchronized withhyoid motion during swallowing5ml of water. The pattern of TP on hard palate in this study was consistent with the previous results in part2. The TP was produced closely tothe hyoid elevation, then reached maximal value a little earlier than the hyoid began stablein the most superior-anterior position but without significance, and ceased concurrentlywith the onset of hyoid descending. Significant positive correlations were found betweencertain time points on the laryngeal signal waveform and the recorded TP.The innovations of this research:1. We firstly introduced the bend sensor which was used to monitor the limb finemotor in the rehabilitation field to non-invasively monitor the hyolaryngeal excursionduring oropharyngeal swallowing.2. This is the first time to read the signal waveform of hyolaryngeal movement frombend sensor objectively by mathematical analysis. This guarantees that the analysis is notaffected by the raters’ subjective judgments.3. We achieved the simultaneous application of tongue pressure sensor sheet andbend sensor during swallowing.4、These results firstly showed the coordination between TP production and hyoidmotion by using bio-sensing system non-invasively, simultaneously, quantitatively. Itcould be beneficial for clinicians to evaluate oral and pharyngeal phases of swallowing aswell as early diagnosis and treatment of dysphagia chair-side and bed-side. |
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