This study explored age- and sex-related differences in orofacial strength. Healthy adult men (N = 88) and women (N = 83) participated in the study. Strength measures were obtained using the Iowa Oral Performance Instrument (IOPI). Anterior and posterior tongue elevation strength measures were obtained using a standard method. Tongue protrusion and lateralization, cheek compression, and lip compression measures utilized adaptors allowing the participant to exert pressure against the bulb in different orientations. Lip and cheek strength measures were greater for men than women, but tongue strength did not differ between sex groups. Strong correlations between age and strength were not observed. However, group comparisons revealed lower tongue protrusion and lateralization strength in the oldest participants. The oldest participants also exhibited lower anterior and posterior tongue elevation strength relative to the middle-age group. Cheek and lip compression strength demonstrated no age-related differences. The current study supplements and corroborates existing literature that shows that older adults demonstrate lower tongue strength than younger adults. Sex differences were noted such that men demonstrated greater lip and cheek strength but not tongue strength. These data add to the literature on normal orofacial strength, allowing for more informed interpretations of orofacial weakness in persons with dysphagia.

Despite the proliferation of oral motor therapies, much controversy exists regarding the application and benefit of neuromuscular treatments (NMTs) such as strength training for alleviating dysarthria and/or dysphagia. Not only is limited empirical support available to validate the use of NMTs, but clinicians may also lack the foundational information needed to judge the theoretical soundness of unstudied treatment strategies. This tutorial reviews the theoretical foundations for several NMTs, including active exercises, passive exercises, and physical modalities. It highlights how these techniques have been used to address neuromuscular impairments in the limb musculature and explores potential applications to the speech and swallowing musculature. Key issues discussed in relation to active exercise are the selection of treatment targets (e.g., strength, endurance, power, range of motion), specificity of training, progression, and recovery. Factors influencing the potential effectiveness of passive exercises and physical modalities are presented, along with discussion of additional issues contributing to the controversy surrounding oral motor therapies.

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A growing literature documents the relationship between tongue strength and oral phase swallowing function. Objective measures of strength have been recommended as more valid and reliable than subjective measures for the assessment of tongue function, yet subjective measures remain the more commonly used clinical method for assessing tongue strength. This study assessed the relationships among subjective and objective measures of tongue strength and oral phase swallowing impairments. Both subjective and objective measures of tongue strength were observed to be good predictors of the presence of oral phase swallowing impairments. The specific oral phase swallowing functions of bolus manipulation, mastication, and clearance were moderately correlated with subjective ratings of tongue strength. Experienced and inexperienced raters appeared to judge tongue strength differently, with the ratings of experienced raters being more predictive of swallowing function.

The findings replicate those of earlier studies demonstrating that lingual strength may be increased with a variety of exercise protocols and confirm that detraining effects may be observed when training is discontinued. The findings further suggest that the lingual musculature may demonstrate less dramatic training specificity than what has been reported for skeletal muscles.

Although some OMIs show promise for enhancing feeding/swallowing in preterm infants, methodological limitations and variations in results across studies warrant careful consideration of their clinical use.

Primary progressive apraxia of speech (PPAOS) is a clinical syndrome in which apraxia of speech is the initial indication of neurodegenerative disease. Prior studies of PPAOS have identified hypometabolism, grey matter atrophy, and white matter tract degeneration in the frontal gyri, precentral cortex, and supplementary motor area (SMA). Recent clinical observations suggest two distinct subtypes of PPAOS may exist. Phonetic PPAOS is characterized predominantly by distorted sound substitutions. Prosodic PPAOS is characterized predominantly by slow, segmented speech. Demographic, clinical, and neuroimaging data (MRI, DTI, and FDG-PET) were analyzed to validate these subtypes and explore anatomic correlates. The Phonetic subtype demonstrated bilateral involvement of the SMA, precentral gyrus, and cerebellar crus. The Prosodic subtype demonstrated more focal involvement in the SMA and right superior cerebellar peduncle. The findings provide converging evidence that differences in the reliably determined predominant clinical characteristics of AOS are associated with distinct imaging patterns, independent of severity.

The findings provide initial evidence that training specificity may be observed in the lingual musculature. The reported effect sizes can inform future studies examining the benefit of training muscle functions underlying speech and swallowing.