Dysphagia after pharyngolaryngeal cancer surgery. Part I: Pathophysiology of postsurgical deglutition

A dysphagia model with denervation of the pharyngeal constrictor muscles in guinea pigs: functional evaluation of swallowing

Introduction

Swallowing impairment is a crucial issue that can lead to aspiration, pneumonia, and malnutrition. Animal models are useful to reveal pathophysiology and to facilitate development of new treatments for dysphagia caused by many diseases. The present study aimed to develop a new dysphagia model with reduced pharyngeal constriction during pharyngeal swallowing.

Methods

We analyzed the dynamics of pharyngeal swallowing over time with the pharyngeal branches of the vagus nerve (Ph-X) bilaterally or unilaterally transected, using videofluoroscopic assessment of swallowing in guinea pigs. We also evaluated the detailed anatomy of the pharyngeal constrictor muscles after the denervation.

Results

Videofluoroscopic examination of swallowing showed a significant increase in the pharyngeal area during swallowing after bilateral and unilateral sectioning of the Ph-X. The videofluoroscopy also showed significantly higher pharyngeal transit duration for bilateral and unilateral section groups. The thyropharyngeal muscle on the sectioned side was significantly thinner than that on the intact side. In contrast, the thickness of the cricopharyngeal muscles on the sectioned and intact sides were not significantly different. The mean thickness of the bilateral thyropharyngeal muscles showed a linear correlation to the pharyngeal area and pharyngeal transit duration.

Discussion

Data obtained in this study suggest that denervation of the Ph-X could influence the strength of pharyngeal contraction during pharyngeal swallowing in relation to thickness of the pharyngeal constrictor muscles, resulting in a decrease in bolus speed. This experimental model may provide essential information (1) for the development of treatments for pharyngeal dysphagia and (2) on the mechanisms related to the recovery process, reinnervation, and nerve regeneration following injury and swallowing impairment possibly caused by medullary stroke, neuromuscular disease, or surgical damage from head and neck cancer.

The Balloon-Based Manometry Evaluation of Swallowing in Patients with Amyotrophic Lateral Sclerosis

The aim of the study was to analyse the disturbances of the oro-pharyngeal swallowing phase of dysphagia in amyotrophic lateral sclerosis (ALS) patients with the use of specific manometric measurements and to evaluate their plausible association with the duration of the disease. Seventeen patients with ALS were evaluated with manometric examinations of the oral and pharyngeal part of the gastrointestinal tract. Tests were carried out by using the oesophageal balloon-based method with four balloon transducers located 5 cm away from each other. The following manometric parameters were analysed: the base of tongue contraction (BTC) and the upper oesophageal sphincter pressure (UESP), and the hypopharyngeal suction pump (HSP) as well as the oro-pharyngeal, pharyngeal and hypopharyngeal transit time and average pharyngeal bolus velocity (oropharyngeal transit time (OTT), pharyngeal transit time (PTT), hypopharyngeal transit time (HTT) and average pharyngeal bolus velocity (APBV), respectively). Manomatric examinations during swallowing in patients with ALS showed significant weakness of BTC, a decrease of HSP and a decrease of the velocity of bolus transit inside the pharynx which were particularly marked between the first and the third examination. Manometric examinations of the oro-pharyngeal part of the gastrointestinal tract are useful and supportive methods in the analysis of swallowing disturbances in ALS patients.

Compensatory Mechanisms in Patients After a Partial or Total Glossectomy due to Oral Cancer

Excision of a part or the whole of tongue due to oral cancer disturbs swallowing and speech. Lower airways aspiration of the swallowed bolus in patients after such oral structures excision is a symptom of major swallowing disorder and may be the cause of aspiration pneumonia. Restoration of oral nutrition is possible after exclusion or reduction of aspiration threat in the patients. Video fluoroscopic evaluation of the swallowing performed at the beginning of the swallowing rehabilitation in 95 patients after a total or partial glossectomy due to oral cancer, who assessed their saliva swallowing as efficient on the day of examination, showed disturbances of all of the swallowing stages. The most common disturbances involved the oral stage: limited mobility of the oral tongue, impaired glossopalatal seal, and weak glossopharyngeal seal. The most serious among them involved pharyngeal stage of swallowing, as leakage into the larynx and aspiration. The patients used their own methods during barium suspension swallowing to facilitate the swallowing act. They used such methods as: changing the position of the head to the body, additional swallows, engaging the adjacent structures into sealing the oral fissure. We assumed that the compensatory mechanisms (CM) worked out by the patients before the swallowing examination will enable them efficient barium suspension swallowing. The CM were applied by 71 of 95 patients; 51 of the patients used more than one compensatory mechanism. Swallowing in 61 of the compensating patients was at least functional; swallowing in 10 of the compensating patients was non-efficient and caused recurrent aspiration. The results of our research negate the validity of multiple swallows (more than three) without apnea elongation because it may lead to aspiration. Aspiration was also recorded in patients with weak airways closure and immovable epiglottis, who complemented the impaired oral transport with gravitational oral transport by moving chin up during a swallow. The hypothesis that CM applied by the patients after oral cancer excision during saliva swallowing will be helpful in swallowing of the barium suspension was not proved. In 10 of all the patients recurring aspiration was found despite CM application. Determination of aspiration risk is the key to efficient swallowing rehabilitation. The assessment of CM applied spontaneously by the patients' maintenance validity is particularly important. Video fluoroscopic examination of swallowing allows to assess the aforementioned issue and is crucial for better comprehension of CM applied by the patients in creating a new swallowing pattern after oral cancer excision.

Oropharyngeal dysphagia

Although the aging process per se can produce measurable changes in the normal oropharyngeal swallow, these changes alone are rarely sufficient to cause clinically apparent dysphagia. The causes of oropharyngeal dysphagia in the elderly are predominantly neuromyogenic, with the most common cause being stroke. The evaluation of oropharyngeal dysphagia in the elderly involves early exclusion of structural abnormalities, detection of aspiration by videofluoroscopy which might dictate early introduction of nonoral feeding, and exclusion of underlying systemic and neuromyogenic causes that have specific therapies in their own right. Such conditions include Parkinson disease, myositis, myasthenia, and thyrotoxicosis. Management is best delivered by a multidisciplinary team involving physician, speech pathologist, nutritionist and, at times, a surgeon.

Comparison of Two Methods for Measuring Tongue Pressure During Swallowing in People with Head and Neck Cancer

Reliable measurement tools are essential to achieve rigor in dysphagia research. In order for tongue pressure to be measured accurately in the head and neck cancer population, where change in function needs to be captured over time, a reliable tool is required. Assessing the reliability of tools that are used in swallowing evaluation has been a neglected area of dysphagia research. This article evaluates and compares the reliability of two variants of the Kay Swallowing Workstation (KSW) three-bulb silicon tongue pressure array (hand-held and fixed-position) when used to capture oral tongue pressures in two groups of participants diagnosed with head and neck cancer who had not yet commenced cancer treatment. Tongue pressure data and videofluoroscopic images were collected and recorded simultaneously onto the KSW while participants swallowed set quantities of liquid and pudding boluses. Peak amplitude tongue pressures were extracted and used in analyses. Systematic and nonsystematic variability were examined using analysis of variance and intraclass correlation coefficients, respectively. The fixed-position array demonstrated better reliability than did the hand-held method. This should be further investigated with a larger participant sample.

[Experiences with intraoperative application of prednisolone during Isshiki type I thyroplasty]

Laryngeal edema is considered a postoperative problem in phonosurgery. In a prospective study we examined if a single intraoperative application of prednisolone can decrease the incidence of postoperative laryngeal edema after Isshiki type I thyroplasty. We examined ten patients undergoing unilateral type I thyroplasty [seven men and three women, age range: 19-60 years (average: 48 years)]. In six patients we administered 250 mg prednisolone i.v. during surgery. In four patients no steroids were given at all. On the 1st and 2nd postoperative day, the larynx was examined in a clinical setting. Five of six patients who received intraoperative steroid medication had no postoperative laryngeal edema. Only in one of those patients we examined a small edema of the arytenoid region. In all four patients without steroid medication a postoperative edema of the ipsilateral arytenoid hump was seen. Thus, intraoperative intravenous steroid administration seems to prevent, or at least reduce, postoperative laryngeal edema. Only in one of those patients we examined a small edema of the arytenoid region.

Current evaluation and treatment of patients with swallowing disorders

To determine the varied causes of oropharyngeal dysphagia and their respective pathophysiology, a working understanding of the normal anatomy and function of the highly integrated mechanism of swallowing is outlined. This information is presented as the basis for a reasoned and detailed approach to the history, physical examination, and endoscopic evaluation of normal and altered oropharyngeal swallowing. The management of swallowing disorders depends on the nature and magnitude of the responsible clinical condition. Conservative and surgical approaches are discussed. These modalities and their indications are described in detail.