Architecture of the Suprahyoid Muscles: A Volumetric Musculoaponeurotic Analysis.

Purpose: Suprahyoid muscles play a critical role in swallowing. The arrangement of the fiber bundles and aponeuroses has not been investigated volumetrically, even though muscle architecture is an important determinant of function. Thus, the purpose was to digitize, model in three dimensions, and quantify the architectural parameters of the suprahyoid muscles to determine and compare their relative functional capabilities. Method: Fiber bundles and aponeuroses from 11 formalin-embalmed specimens were serially dissected and digitized in situ. Data were reconstructed in three dimensions using Autodesk Maya. Architectural parameters were quantified, and data were compared using independent samples t-tests and analyses of variance. Results: Based on architecture and attachment sites, suprahyoid muscles were divided into 3 groups: anteromedial, superolateral, and superoposterior. Architectural parameters differed significantly (p < .05) across muscles and across the 3 groups, suggesting differential roles in hyoid movement during swallowing. When activated simultaneously, anteromedial and superoposterior muscle groups could work together to elevate the hyoid. Conclusions: The results suggest that the suprahyoid muscles can have individualized roles in hyoid excursion during swallowing. Muscle balance may be important for identifying and treating hyolaryngeal dysfunction in patients with dysphagia.

Valid and reliable techniques for measuring fibrosis in patients with head and neck cancer postradiotherapy: A systematic review.

BACKGROUND: Fibrosis is a common side effect of radiotherapy for head and neck cancer. Although treatments for fibrosis have been developed, valid and reliable measurement tools are needed to verify their efficacy. The purpose of this review was to identify and appraise tools used to measure head and neck fibrosis. METHODS: Electronic databases were searched for primary research published through April 2014. Main search terms included head and neck cancer, radiotherapy, fibrosis, validity, and reliability. Methodological quality was assessed using Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). Two blinded raters conducted all assessments. Discrepancies were resolved by consensus. RESULTS: The search retrieved 534 unique citations. Nine studies met our inclusion criteria, representing 9 different tools. Only 1 tool was assessed for reliability and validity. QUADAS-2 revealed that all studies were at risk for bias. CONCLUSION: To date, there are no valid and reliable techniques for measuring fibrosis postradiotherapy for head and neck cancer, especially within the suprahyoid and pharyngeal regions. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2322-E2334, 2016.

The effect of prophylactic percutaneous endoscopic gastrostomy (PEG) tube placement on swallowing and swallow-related outcomes in patients undergoing radiotherapy for head and neck cancer: a systematic review.

Patients undergoing radiotherapy for head and neck cancer (HNC) often experience malnutrition and dehydration during treatment. As a result, some centres place PEG tubes prophylactically (pPEG) to prevent these negative consequences. However, recent research has suggested that pPEG use may negatively affect swallowing physiology, function and/or quality of life, especially in the long term. The purpose of this study was to systematically review the literature on pPEG use in HNC patients undergoing radiotherapy and to determine its impact on swallowing-related outcomes. The following electronic databases were searched for all relevant primary research published through February 24, 2014: AMED, CINAHL, the Cochrane Library, Embase, Healthstar, Medline, and PsycINFO. Main search terms included HNC, radiotherapy, deglutition disorders, feeding tube(s), and prophylactic or elective. References for all accepted papers were hand searched to identify additional relevant research. Methodological quality was assessed using Cochrane's Risk of Bias. At all levels, two blinded raters provided judgments. Discrepancies were resolved by consensus. The search retrieved 181 unique citations. Twenty studies met our inclusion criteria. Quality assessment revealed that all studies were at risk for bias due to non-randomized sampling and unreported or inadequate blinding. Ten studies demonstrated selection bias with significant baseline differences between pPEG patients and controls. Results regarding the frequency and severity of dysphagia and swallowing-related outcomes were varied and inconclusive. The impact of pPEG use on swallowing and swallowing-related outcomes remains unclear. Well-controlled, randomized trials are needed to determine if pPEG places patients at greater risk for developing long-term dysphagia.

The normal swallow: muscular and neurophysiological control.

Swallowing is a complex physiologic function that involves precisely coordinated movements within the oral cavity, pharynx, larynx, and esophagus. This article reviews the anatomy, muscular control, and neurophysiological control of normal, healthy swallowing.

Frequency response of synthetic vocal fold models with linear and nonlinear material properties.

PURPOSE: The purpose of this study was to create synthetic vocal fold models with nonlinear stress-strain properties and to investigate the effect of linear versus nonlinear material properties on fundamental frequency (F0) during anterior-posterior stretching. METHOD: Three materially linear and 3 materially nonlinear models were created and stretched up to 10 mm in 1-mm increments. Phonation onset pressure (Pon) and F0 at Pon were recorded for each length. Measurements were repeated as the models were relaxed in 1-mm increments back to their resting lengths, and tensile tests were conducted to determine the stress-strain responses of linear versus nonlinear models. RESULTS: Nonlinear models demonstrated a more substantial frequency response than did linear models and a more predictable pattern of F0 increase with respect to increasing length (although range was inconsistent across models). Pon generally increased with increasing vocal fold length for nonlinear models, whereas for linear models, Pon decreased with increasing length. CONCLUSION: Nonlinear synthetic models appear to more accurately represent the human vocal folds than do linear models, especially with respect to F0 response.