BACKGROUND: Recent research confirmed that at least a third of people with multiple sclerosis (MS) are suffering from swallowing difficulties. Dysphagia is associated with significant morbidity and mortality, and has profound impact on physical ability and quality of life. Dysphagia related complications can be prevented through an effective screening protocol. The Dysphagia in Multiple Sclerosis (DYMUS) questionnaire is the first dysphagia questionnaire developed specifically for patients with MS. The aim of the present study was the cultural adaptation of DYMUS for the Greek population, evaluation of the questionnaire's reliability and validity and normative data generation for DYMUS, which has not been published before.METHODS: DYMUS was completed by 200 participants: 108 MS patients and 92 asymptomatic subjects (60 male and 140 female). Patients with MS were consecutively recruited from the Multiple Sclerosis Centre during regular visits. Asymptomatic participants were community-dwelling healthy persons. All data were collected prospectively. MS patients were invited to complete DYMUS and the Greek versions of the Eating Assessment Tool-10 (EAT-10), and the Swallowing-Quality of Life (SWAL-QoL) questionnaires. Healthy subjects completed DYMUS and the Greek EAT-10. The study consisted of item generation for the Greek DYMUS, internal consistency and reliability analysis, normative data generation, and validity analysis. Criterion validity was assessed by comparing scores between groups with expected differences: MS patients and healthy participants. Construct validity was assessed by comparison of DYMUS scores of dysphagic and non dysphagic patients. DYMUS was also validated against EAT-10, and SWAL-QoL to assess its convergent validity.RESULTS: DYMUS was completed by all participants in less than 3 min. The internal consistency was excellent (Cronbach's alpha was 0.866). Test-retest reliability was good (Pearson's correlation coefficient was 0.637). The mean DYMUS score for the healthy cohort was 0.23 ± 0.471. The upper limit of normal was 1.172. MS patients had statistically significantly higher score than controls (Mann Whitney test, p < 0.001). DYMUS mean score was statistically significantly higher in the dysphagic compared to the non dysphagic MS patients (Mann Whitney test, p < 0.001). There was a strong positive and statistically significant correlation between DYMUS and EAT-10 (Pearson's Correlation coefficient, r = 0.754, p = 0). In the MS patients cohort 25.9% reported themselves as dysphagic, 34.3% were classified as dysphagic according to EAT-10 and 44.4% according to DYMUS. The DYMUS score had a statistically significant positive correlation with the EDSS score, (Mann Whitney, p < 0.001) whereas age, sex, type of MS and disease duration were not significantly correlated. Based on our data analysis we propose the modification of DYMUS to a 9-items tool eliminating the question about weight loss. A DYMUS score of 2 or higher is indicating dysphagia for both the original DYMUS and the modified DYMUS.CONCLUSIONS: The Greek version of DYMUS was found to be a valid, reliable and practical for clinical use questionnaire for the detection of dysphagia in Multiple Sclerosis. The first reported normative data for DYMUS suggest a cut-off for the diagnosis of dysphagia at 2 and our findings support a modification of DYMUS eliminating the question about weight loss.