Faculty Bibliography

A literature review was conducted on temporal measures of swallowing in healthy individuals with the purpose of determining the degree of variability present in such measures within the literature. A total of 46 studies that met inclusion criteria were reviewed. The definitions and descriptive statistics for all reported temporal parameters were compiled for meta-analysis. In total, 119 different temporal parameters were found in the literature. The three most-frequently occurring durational measures were upper esophageal sphincter opening, laryngeal closure, and hyoid movement. The three most-frequently occurring interval measures were stage transition duration, pharyngeal transit time, and duration from laryngeal closure-to-UES opening. Subtle variations in operational definitions across studies were noted, making the comparison of data challenging. Analysis of forest plots compiling descriptive statistical data (means and 95% confidence intervals) across studies revealed differing degrees of variability across durations and intervals. Two parameters (UES opening duration and the laryngeal closure-to-UES opening interval) demonstrated the least variability, reflected by small ranges for mean values and tight confidence intervals. Trends emerged for factors of bolus size and participant age for some variables. Other potential sources of variability are discussed.

This study involved a direct blinded comparison between the results of a brief, standardized swallowing screening protocol and videofluoroscopy of exactly the same swallows. Forty adults participated. Each participant completed a brief swallow screening protocol involving tongue lateralization, voluntary cough, a voice task, and 2 swallowing tasks (3 swallows of 5cc thin liquid barium suspension and a cup-drinking task). We collected time-linked radiographic data and a high-definition movie of the participant's face, head and neck. The movie data were rated by 7 blinded clinicians (nurses and speech-language pathologists) for evidence of clinical signs associated with dysphagia. The videofluoroscopy data were rated by a separate panel of blinded speech-language pathologists for evidence of penetration-aspiration and post-swallow pharyngeal residues. Predictive statistics were calculated for the movie rating results, compared to the videofluoroscopy results. The results showed that none of the screening questions met our criteria for adequate predictive power: sensitivity, specificity and negative predictive values > 0.6, a false negative rate < 0.2 and a positive likelihood ratio > 1.0. We conclude that swallow screening decisions based on a series of 3-4 thin liquid swallows do not have good clinical utility for detecting dysphagia or penetration-aspiration. We discuss a number of issues in swallow screening research that may have contributed to the difference in these results compared to other studies.

A literature review was conducted on hyoid and/or laryngeal displacement during swallowing in healthy populations according to several inclusion criteria. Anterior and superior displacement measures of both structures from previously published studies were compiled for meta-analysis. Results showed a large degree of variability across studies for each structure and plane of movement. Potential sources of variation were identified, including statistical, methodological, stimulus-related, and participant-related sources.

In this study we explored the validity of clinician judgments of voice abnormalities as indicators of penetration-aspiration or other swallowing abnormalities. Voice samples were collected using a high-quality microphone from 40 adults during videofluoroscopy (VFSS), at baseline and following each of four thin liquid swallows. Blinded speech-language pathologists (SLPs) rated the audio recordings for voice quality using the GRBAS scale and the VFSS recordings for abnormal swallow onset, penetration-aspiration, airway closure, and pharyngeal residues. Acoustic measures of % jitter, % shimmer, and signal-to-noise ratio were calculated using two /a/ vowel segments spliced from each voice recording. Preswallow to postswallow measures of voice-quality change were derived and the data were compared to determine the correspondence between perceived voice abnormalities, acoustic voice parameters, and radiographically confirmed swallowing abnormalities. The sensitivity of perceived postswallow changes in voice quality to dysphagia and penetration-aspiration was poor, ranging from 8 to 29%. Specificity was stronger for both penetration-aspiration (75-94%) and dysphagia (59-86%). Acoustic measures of voice quality had moderate sensitivity and specificity for both dysphagia and penetration-aspiration. Overall, perceptual judgments of postswallow wet voice showed the strongest potential for detecting penetration-aspiration (relative risk = 3.24). We conclude that a clear postswallow voice quality provides reasonable evidence that penetration-aspiration and dysphagia are absent. However, observations of abnormal postswallow voice quality can be misleading and are not a valid indication that penetration-aspiration or dysphagia exists.

OBJECTIVES: Reduced range of hyoid and laryngeal movement is thought to contribute to aspiration risk and pharyngeal residues in dysphagia. Our aim was to determine the extent to which movements of the hyoid and larynx are correlated in the superior and anterior directions in swallowing, and whether movement range is predictive of penetration-aspiration or pharyngeal residue. DESIGN: Prospective, single-blind study of penetration-aspiration and pharyngeal residue with objective frame-by-frame measures of hyoid and laryngeal excursion from videofluoroscopy. SETTING: Tertiary hospital and rehabilitation teaching hospital. PARTICIPANTS: Twenty-eight participants referred for videofluoroscopy: 13 women, aged 57-77; 15 men, aged 54-70. Individuals with known neurodegenerative diseases or prior surgery to the neck were excluded. Each swallowed three boluses of 40% w/v thin liquid barium suspension. OUTCOMES: Two speech-language pathologists independently rated penetration-aspiration, vallecular and pyriform sinus residue. Cervical spine length, hyoid and laryngeal displacement were traced frame-by-frame. Predictive power was calculated. RESULTS: Cervical spine length was significantly greater in men. Hyoid displacement ranged from 34-63% of the C2-4 distance. Arytenoid displacement ranged from 18-66%, with significantly smaller anterior displacement in men. Positive hyoid-laryngeal movement correlations in both axes were the most common pattern observed. Participants with reduced displacement ranges (