Sarcopenic Dysphagia Reconsidered: A Systematic Review of Complex Interactions and Diagnostic Challenges

Sarcopenic dysphagia is an emerging clinical concept defined as dysphagia resulting from generalized sarcopenia and sarcopenic changes in the muscles involved in swallowing. However, despite growing clinical interest, its diagnostic criteria, pathophysiological boundaries, and causal validity remain insufficiently established. This systematic review aimed to examine how sarcopenic dysphagia has been defined and assessed in the literature and to identify conceptual and methodological gaps. A comprehensive literature search was conducted across PubMed, EMBASE, the Cochrane Library, and CINAHL, covering all records from database inception through December 2024. Studies were included if they explicitly used and defined the term "sarcopenic dysphagia." A total of 31 studies were included, comprising 20 observational studies and 11 case reports. Definitions varied considerably across studies, from structured diagnostic frameworks to the co-occurrence of sarcopenia and dysphagia. Many studies included patients with comorbidities known to independently cause dysphagia, such as neurologic disease or head and neck cancer, thereby complicating causal inference. Given the numerous shared risk factors and known associations between sarcopenia and dysphagia, interpreting a direct causal relationship requires careful consideration. Moreover, swallowing function is influenced by factors beyond muscle mass and strength, including neuromuscular coordination and age-related physiological changes. This systematic review highlights that the current conceptualization of sarcopenic dysphagia is challenged by the complex influence of multifactorial etiologies, the association between sarcopenia and dysphagia, and methodological limitations in swallowing assessment. Future research may require prospective longitudinal studies using standardized, objective measures to clarify the complex interplay between sarcopenia and swallowing dysfunction.