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.

Purpose Sarcopenia of swallowing muscles is a potential cause of dysphagia. We investigated age-related changes in mass and quality of swallowing muscles by ultrasonography as a non-invasive and convenient examination in subjects without dysphagia. Methods A total of 104 subjects (34 males, 70 females) participated in this study. Age, physical status, and mass and strength of skeletal and swallowing muscles were investigated. Ultrasonography was performed to measure cross-sectional area and brightness of the geniohyoid muscle as a swallowing muscle. Calf circumference was measured to evaluate skeletal muscle mass. Hand grip strength was measured to evaluate skeletal muscle strength. Subjects were divided into two groups: young (< 65 years old) and old (≥ 65 years old). We performed univariate and multivariate analyses to analyze the differences between the groups. Results The number of subjects in the young group was 35, and 69 in the old group. The mean ± SD of measurements in each group was as follows (young/old): age, 35.4 ± 13.9/74.5 ± 5.5 years old; calf circumference, 37.4 ± 4.1/33.9 ± 2.7 cm (p < 0.001); hand grip strength, 35.6 ± 10.2/25.8 ± 7.6 kg (p < 0.001); cross-sectional area of geniohyoid muscle, 229.5 ± 52.2/174.1 ± 40.7 mm² (p < 0.001); and brightness of geniohyoid muscle, 46.6 ± 11.1/59.6 ± 10.8 (p < 0.001). The old group had a significantly smaller geniohyoid muscle area and significantly greater geniohyoid muscle brightness than the young group (p < 0.01). Age and calf circumference were independent explanatory factors for geniohyoid muscle area (p < 0.01). Age and sex were independent explanatory factors for geniohyoid muscle brightness (p < 0.01). Conclusions Ultrasonography revealed a smaller area and greater brightness, which suggested smaller mass and greater infiltration of fat, in the geniohyoid muscle in old people than in young people.

Background: The effect of sarcopenia on the recovery of swallowing function, and the interaction among sarcopenia, nutrition care, and rehabilitation therapy are inconclusive. Methods: This multicenter cohort study was conducted between November 2018 and October 2020 in convalescent rehabilitation hospitals in Japan and included post-stroke patients aged ≥65 years with dysphagia. All participants were assigned to sarcopenia and non-sarcopenia groups. The primary outcome was the achievement of ≥2 Food Intake Level Scale [FILS] gain, and the secondary outcomes included Functional Independence Measure (FIM) gain and efficiency. Considering the effect modification of energy intake and rehabilitation duration, logistic regression analyses were performed. Results: Overall, 153 participants with (median age, 82 years; 57.5% women) and 40 without (median age 75 years; 35.0% women) sarcopenia were included. The non-sarcopenia group had more patients who achieved an FILS gain of ≥2 (75.0%) than the sarcopenia group (51.0%). Sarcopenia was independently associated with a poor FILS gain (odds ratio:0.34, 95% confidence intervals: 0.13–0.86) but not associated with FIM gain or efficiency. This association was not affected by the rehabilitation duration or energy intake. Conclusions: In conclusion, sarcopenia was negatively associated with the recovery of swallowing function in stroke patients without interaction by energy intake and rehabilitation duration.