Muscle Strengthening Approaches to Dysphagia Rehabilitation

Physiology of the tongue with emphasis on taste transduction

The tongue is a complex multifunctional organ that interacts and senses both interoceptively and exteroceptively. Although it is easily visible to almost all of us, it is relatively understudied and what is in the literature is often contradictory or is not comprehensively reported. The tongue is both a motor and a sensory organ: motor in that it is required for speech and mastication, and sensory in that it receives information to be relayed to the central nervous system pertaining to the safety and quality of the contents of the oral cavity. Additionally, the tongue and its taste apparatus form part of an innate immune surveillance system. For example, loss or alteration in taste perception can be an early indication of infection as became evident during the present global SARS-CoV-2 pandemic. Here, we particularly emphasize the latest updates in the mechanisms of taste perception, taste bud formation and adult taste bud renewal, and the presence and effects of hormones on taste perception, review the understudied lingual immune system with specific reference to SARS-CoV-2, discuss nascent work on tongue microbiome, as well as address the effect of systemic disease on tongue structure and function, especially in relation to taste.

Myogenic marker expression as a function of age and exercise-based therapy in the tongue

Degeneration of tongue muscles with aging may contribute to swallowing deficits observed in elderly people. However, the capacity for tongue muscle stem cells (SCs) to regenerate and repair the aged tongue and improve tongue strength following tongue exercise (a current clinical treatment) has never been examined. We found that the expression of regenerative, myogenic markers were impaired with age and may be related to increased expression of senescent marker p16INK4a. Tongue strength increased in young adult and old rats following exercise and was related to the expression of Pax7, MyoD, myogenin, and p16INK4a. Our study also suggests that strengthening of tongue muscles via clinical rehabilitation strategies also increased the expression of SC regenerative markers in the tongue throughout the exercise duration.

Shifting Tides Toward a Proactive Patient-Centered Approach in Dysphagia Management of Neurodegenerative Disease

Purpose Persons with neurodegenerative disease frequently develop comorbid dysphagia as part of their disease process. Current "reactive" approaches to dysphagia management address dysphagia once it manifests clinically and consist of compensatory approaches. The purpose of this article is to propose a paradigm shift in dysphagia management of patients with neurodegenerative disease from a "reactive to proactive" approach by highlighting amyotrophic lateral sclerosis (ALS) and dementia as case examples. Method The authors present several areas of special consideration for speech-language pathologists (SLPs) treating dysphagia in patients with neurodegenerative disease. The drawbacks of historical "reactive" approaches to dysphagia management are described. Concepts of functional reserve for swallowing and homeostenosis are discussed. A "proactive" patient-centered paradigm of care for these patients is proposed with evidence to support its importance. A rationale for use of this approach in patients with ALS and dementia is provided with strategies for implementation. Results When treating dysphagia in patients with neurodegenerative disease, SLPs must balance a variety of factors in their decision making, including disease severity and expected progression, cultural considerations, goals of care, patient empowerment, and caregiver support. Reactive approaches to dysphagia management in these populations are problematic in that they disempower patients by focusing on use of compensatory techniques (e.g., diet modification, postural changes, feeding tube placement). Proactive approaches that employ rehabilitative interventions to increase functional reserve, such as resistance training, may result in improvement or maintenance of swallowing function longer into disease progression. An interdisciplinary team with early SLP involvement is necessary. Conclusions SLPs play a critical role in the management of dysphagia in patients with neurodegenerative disease and should be integrated early in the care of these patients. By focusing on a proactive patient-centered approach, patients with neurodegenerative conditions, such as ALS and dementia, will experience improved quality of life and health outcomes for a longer time.