Sarcopenia and dysphagia: Position paper by four professional organizations.

This report was written by the Japanese Society of Dysphagia Rehabilitation, the Japanese Association of Rehabilitation Nutrition, the Japanese Association on Sarcopenia and Frailty, and the Society of Swallowing and Dysphagia of Japan to consolidate the currently available evidence on the topics of sarcopenia and dysphagia. Histologically, the swallowing muscles are of different embryological origin from somatic muscles, and receive constant input stimulation from the respiratory center. Although the swallowing muscles are striated, their characteristics are different from those of skeletal muscles. The swallowing muscles are inevitably affected by malnutrition and disuse; accumulating evidence is available regarding the influence of malnutrition on the swallowing muscles. Sarcopenic dysphagia is defined as dysphagia caused by sarcopenia of the whole body and swallowing-related muscles. When sarcopenia does not exist in the entire body, the term "sarcopenic dysphagia" should not be used. Additionally, sarcopenia due to neuromuscular diseases should be excluded; however, aging and secondary sarcopenia after inactivity, malnutrition and disease (wasting disorder and cachexia) are included in sarcopenic dysphagia. The treatment of dysphagia due to sarcopenia requires both dysphagia rehabilitation, such as resistance training of the swallowing muscles and nutritional intervention. However, the fundamental issue of how dysphagia caused by sarcopenia of the swallowing muscles should be diagnosed remains unresolved. Furthermore, whether dysphagia can be caused by primary sarcopenia should be clarified. Additionally, more discussion is required on issues such as the relationship between dysphagia and secondary sarcopenia, as well as the diagnostic criteria and means for diagnosing dysphagia caused by sarcopenia. Geriatr Gerontol Int 2019; 19: 91-97.