Coordination of mastication and swallowing

The coordination of mastication, oral transport, and swallowing was examined during intake of solids and liquids in four normal subjects. Videofluorography (VFG) and electromyography (EMG) were recorded simultaneously while subjects consumed barium-impregnated foods. Intramuscular electrodes were inserted in the masseter, suprahyoid, and infrahyoid muscles. Ninety-four swallows were analyzed frame-by-frame for timing of bolus transport, swallowing, and phases of the masticatory gape cycle. Barium entered the pharynx a mean of 1.1 s (range −0.3 to 6.4 s) before swallow onset. This interval varied significantly among foods and was shortest for liquids. A bolus of food reached the valleculae prior to swallow onset in 37% of sequences, but most of the food was in the oral cavity at the onset of swallowing. Nearly all swallows started during the intercuspal (minimum gape) phase of the masticatory cycle. Selected sequences were analyzed further by computer, using an analog-to-digital convertor (for EMG) and frame grabber (for VFG). When subjects chewed solid food, there were loosely linked cycles of jaw and hyoid motion. A preswallow bolus of chewed food was transported from the oral cavity to the oropharynx by protraction (movement forward and upward) of the tongue and hyoid bone. The tongue compressed the food against the palate and squeezed a portion into the pharynx one or more cycles prior to swallowing. This protraction was produced by contraction of the geniohyoid and anterior digastric muscles, and occurred during the intercuspal (minimum gape) and opening phases of the masticatory cycle. The mechanism of preswallow transport was highly similar to the oral phase of swallowing. Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.     

Solid swallowing versus water swallowing: manometric study of dysphagia

The aim of the study was to investigate whether a soft solid bolus can induce abnormal manometric patterns in patients with dysphagia and normal standard manometry. The study group comprised 12 normal volunteers and 22 patients with dysphagia. Manometry was performed using 10 wet swallows followed by 10 swallows of marshmallow. The results show: (1) in normal subjects the mean contraction amplitude is significantly greater (P<0.035) and the velocity of propagation significantly slower (P<0.003) for soft solid swallows compared with wet swallows; (2) in normal subjects there are fewer abnormal contractions after soft solid swallows than after wet swallows; (3) in 15 patients, soft solid swallows induced nonperistaltic contractions and/or contractions of extreme amplitude and/or duration that were not observed after wet swallows; 94) in patients, the probability of inducing abnormal contractions after soft solid swallows is significantly greater than after wet swallows (P<0.0001). We conclude that soft solid swallowing is useful in the study of patients with dysphagia.Part of this work was presented by Dr. Argaman as a thesis, to the Technion Medical School, for his MD.     

Syncope in the act of swallowing (swallowing syncope)

In a 30-year-old female patient with recurrent syncope during swallowing, intermittent complete AV-block was documented as the underlying mechanism. This phenomenon could be provoked by inflating a balloon positioned in the lower esophagus. The His-bundle electrocardiogram, recorded simultaneously, showed a progressive increase of the normal AH-interval, up to complete block distal to the A-wave. Atropine prevented induction of the block. After implantation of a VVI pacemaker, the symptoms disappeared completely. This very rare phenomenon of swallowing syncope is probably due to a pathologic vago-vagal reflex.     

The videoendoscopic swallowing study: An alternative and partner to the videofluoroscopic swallowing study

A new, physical examination-based videoendoscopic method of evaluation can enhance considerably the understanding and efficiency of clinicians working with patients with swallowing difficulties. Using the fiberoptic nasolaryngoscope, evaluation of structure and function of palate, pharynx, and larynx, along with sensation of the laryngopharynx, is carried out. Next, patients' swallowing capabilities are assessed as they ingest various food consistencies. This method, formerly called videoendoscopic evaluation of dysphagia (VEED), but perhaps more appropriately termed videoendoscopic swallowing study (VESS) has particular value for patients who cannot undergo the videofluoroscopic swallowing study (VFSS)—for example, because they are bedfast-or those whose swallowing function is changing so rapidly (after a stroke or surgery) as to call for frequent reassessments. This technique is often useful during the initial consultation with new patients complaining of dysphagia, as a stand alone method of diagnosis and management. Less frequently, VESS findings, along with patient history, will indicate when VFSS should also be obtained. VESS will orient the examiner to the nature and severity of the problem even in this latter circumstance. In follow-up circumstances, VESS is generally more useful than the VFSS. Case presentations are utilized to illustrate the usefulness of VESS as compared to VFSS.     

Spontaneous swallowing rate and emotional state

Excessive spontaneous swallowing has been associated with a variety of common gastrointestinal symptoms including abdominal pain, heartburn, and bloating and may contribute to disorders such as hiatus hernia, duodenal ulcer, and irritable bowel syndrome. The present study investigated the hypothesis that changes in emotional state alter spontaneous swallowing rate. Subjects were 38 generally healthy undergraduates assigned to either a pleasant low arousal, neutral, or aversive high arousal condition. Each experimental session was divided into 30-min baseline and arousal manipulation periods. Spontaneous swallowing rate increased significantly with emotional arousal: for low, neutral, and high arousal groups, means were 7.9±1.9 (se), 15.8±2.4, and 23.7±3.6 swallows/30 min, respectively. Other physiological and self-report measures, used to check the effectiveness of the arousal manipulation, varied appropriately with experimental procedures. These results indicate that changes in emotional state alter spontaneous swallowing rate in generally healthy individuals. Further research with patients is needed to establish whether stress-induced increases in swallowing rate produce or exacerbate clinically significant gastrointestinal symptomatology.     

Using ventilators for speaking and swallowing

An inflated cuff, although commonly though to be required for the ventilator-dependent patient with a tracheostomy cannula, precludes speaking and has adverse implications for swallowing. Clinical trials with five ventilator-dependent, cognitively intact individuals with glottic control document that a deflated cuff is compatible with ventilation, preserves oral communication, and restores safe alimentation by mouth. Presneted initially at: The Third Symposium on Dysphagia, March 23, 1990; and The Annual Convention of the Maryland State Speech-Language-Hearing Association, April 6, 1990     

卒中后吞咽障碍荧光透视与临床吞咽功能的相关性

目的探讨吞咽障碍患者的临床表现与吞咽荧光透视检查(VFSS)所示结构和功能的相关性。方法连续收集2012年6月—2014年5月浙江中医药大学附属温州市中医院收治的56例卒中后吞咽障碍患者,选择性应用4种不同质地的食物进行测试,分别完成临床吞咽功能评估和VFSS检查,并用SPSS 20.0统计软件对该两种方法的各项观察指标进行单因素分析和多因素Logistic回归分析。结果临床表现与VFSS检查的点对应关系在口腔期有口内食物残留与口唇闭合异常(95%CI:1.430~101.468,P=0.022);软腭上抬差与口腔食物残留(95%CI:1.476~102.033,P=0.020);分次吞咽与口通过时间延长(95%CI:2.616~182.897,P=0.004);舌运动障碍及软腭上抬差与食团形成障碍(95%CI分别为1.468~50.795、1.220~13.825,P值分别为0.017、0.023);食物口角漏出、咽下困难与食团从舌根掉落会厌或气管(95%CI分别为1.146~125.459、1.657~174.400,P值分别为0.038、0.017)。在咽期主要有咽反射减弱与喉上抬程度弱(95%CI:1.150~92.815,P=0.037);咽下困难、吞咽延迟与吞咽反射启动触发时间长(95%CI分别为2.123~37.770、1.233~114.176,P值分别为0.003、0.032);分次吞咽、用力吞咽、哽噎感以及喉上抬差与咽期通过时间长(95%CI分别为1.619~223.316、1.061~31.445、2.834~132.707,P值分别为0.019、0.042、0.003);咽下困难与环咽肌开放不全(95%CI:1.037~24.115,P=0.045);喉上抬程度弱、咽部异物感、吞咽后呛咳与会厌谷或梨状窝滞留或残留(95%CI分别为1.046~13.685、1.116~87.741,P值分别为0.043、0.040);吞咽过程中咳嗽、进食呛咳与误吸(95%CI分别为0.010~0.921、0.037~0.826,P值分别为0.042、0.028)等,均存在明显相关性。结论某些临床症状表现与VFSS检查发现的吞咽功能异常密切相关,借助该规律可更简捷、安全地判断患者吞咽障碍程度及类型,为不能接受VFSS检查的卒中后吞咽障碍患者进行康复治疗作指导。     

Tachyarrhythmias triggered by swallowing and belching

Three cases with supraventricular tachyarrhythmias related to oesophageal transit are reported. A 61 year old man had episodes of atrial tachycardia on each swallow of food but not liquid; this has been reported only rarely. A 55 year old man had atrial fibrillation initiated by drinking ice cold beverages; this has not been described previously although atrial tachycardia triggered by drinking ice cold beverages has been described once. A 68 year old man had supraventricular tachycardia initiated by belching; this has not been described previously. These cases illustrate the diversity of atrial tachyarrhythmias that can be precipitated by oesophageal stimulation and suggest that what is regarded as a very rare phenomenon may be found more commonly when sought.     

Symmetry and reproducibility of swallowing sounds

Cervical auscultation is being used more frequently in the clinical assessment of dysphagic patients. The present study was designed to assess symmetry and the reproducibility of swallowing sounds detected simultaneously from bilateral cervical sites. Symmetry of the swallowing sounds acquired using our method was verified because no significant differences were found for any parameters in both time and frequency domain analyses between swallowing sounds detected bilaterally. This result supports the use of a unilateral site for the detection of swallowing sounds. The reproducibility of swallowing sounds was assessed by a coefficient of variation. Results of this analysis suggest that one should evaluate the acoustic characteristics of swallowing sounds from repeated swallows rather than from one swallow.     

Neurological and neuromuscular aspects of swallowing

Issued in theNIII Guide to Grants and Contracts, January 22, 1988.     

Volume accommodation during swallowing

Bolus volume is an important modifier of the biomechanical events of the oropharyngeal swallow. The biomechanical events comprising a swallow can be divided into events associated with the reconfiguration of the pharynx into a swallow pathway and events associated with bolus transport from the oropharynx into the esophagus. Volume modification is achieved differently for the events of reconfiguration and propulsion. In the case of reconfiguration, a longer time is allocated to the process, as exemplified by sustained laryngeal elevation and hyoid excursion during larger volume swallows. On the other hand, in the case of bolus expulsion, volume accommodation is accomplished within the same period of time by utilizing increased vigor of expulsion. The result of deglutitive volume accommodation is a remarkably different fluoroscopic appearance of a small vs. a large volume swallow. The larger volume swallow seemingly takes longer and results in much more vigorous bolus expulsion than a small volume. However, this is more related to the bolus than the swallow.     

Characteristics and limitation of portable bedside swallowing test in elderly with dementia: comparison between the repetitive saliva swallowing test and the simple swallowing provocation test

Several bedside portable swallowing tests have been advocated for screening for dysphagia. However, the clinical usefulness and limitation of these tests have not been examined in elderly patients with dementia. We performed the repetitive saliva swallowing test (RSST) and the simple swallowing provocation test (SSPT) in 37 elderly inpatients (81.8 +/- 1.2 years old). Simultaneously, cognitive and verbal communication ability were assessed by the Hasegawa Dementia Scale revised version (HDSR) and the Mini-Communication Test (MCT). RSST was completed only in 22 patients (59%), whereas SSPT was successfully completed in all cases. Scores of HDSR and MCT were significantly lower in patients who were unable to cooperate with RSST compared to successful examinees (HDSR: 7 +/- 1 vs 15 +/- 3, p < 0.0; MCT: 47 +/- 8 vs 81 +/- 5, p < 0.01). Dysphagia was detected in 14 patients (64%) by RSST and 5 (14%) by SSPT. Patients with dysphagia showed significantly lower cognitive function (p < 0.05) and verbal communication ability (p < 0.05). In conclusion, RSST is more sensitive to detect dysphagia in elderly patients; however, compliance with RSST is strongly influenced by the patient's cognitive function and verbal communication ability. Comprehensive geriatric assessment will help to choose an alternative test for dysphagia such as SSPT which is more specific test for aspiration pneumonia.     

Neurophysiological basis of swallowing

The neurophysiological control of swallowing involves three functionally distinct divisions: the oral preparatory phase, a pharyngolaryngeal phase and an esophageal phase. Both the pharyngeal and esophageal phases involve control by interneurons in different regions of the reticular formation of the medulla within the brain stem. The central neural control of the brain stem is triggered by specific patterns of sensory or descending cortical input. The threshold that will elicit swallowing depends upon the type of stimuli (i.e., specific fluids, touch, pressure). The threshold is higher if much of the pharyngeal mucosa is anesthetized and if salivation is inhibited. Sensory feedback does change the threshold and intensity of sequential muscle recruitment. Descending pathways that modify swallowing include the prefrontal cortex, the limbic-hypothalamic system, and specific regions of the pons.