Test-retest reliability of electromyographic variables of masticatory muscles, at rest and during movement, associated with the quality of sleep and life in patients with Down syndrome

Abstract

Down Syndrome (SD), also known as Trisomy 21, is a chromosomal disorder caused by the presence of all or part of an extra-chromosome 21. This condition is the most frequent chromosomal abnormality, particularly associated with an intellectual disability. Its incidence is around 1 in each 700 neonates. This genetic disorder is attributed to the trisomy (92 to 95% of the cases), the mosaicism (2 to 4%), and the translocation of the chromosome 21 (3 to 5%) to other acrocentric chromosome often to the chromosome 14. This translocation can occur during the formation of reproductive cells in a progenitor or in the fetus development. Regarding the orofacial characteristics, these individuals often have syndromic facial expression, craniolateral oblique eyelids, protruding tongue resting on the lower incisors (pseudomacroglossia), and a suggestive alteration of salivary flow. Other condition is generalized muscle hypotonia, resulting in an impaired muscle synergy. These facts can trigger expressive clinical complications as masticatory dysfunction, speech disorder, and dysphagia. Objective: The aim of this study will be to determinate the "within-day" and "between-day" reliability of electromyographic variables of the masticatory muscles in patients with SD. In addition, we will assess the risk of Sleep Obstructive Apnea Syndrome (SOAS) and its effect in the individuals' social life through specific questionnaires. Methodology: The superficial electromyography will be performed on the right and left masseter muscles (superficial portion), right and left temporal muscles (anterior portion), and suprahyoid muscle in 30 patients with Down's syndrome. The electrical activities of these muscles will be evaluated in the following conditions: at rest, at maximum clenching effort, during the dynamic of mouths opening and closing, and total masticatory force. These electromyographic records will be performed in triplicate and in three consecutive sessions, with a minimum interval of 7 days in each session. The obtained data will be analyzed using the root mean square amplitude, mean frequency, median frequency, zero crossing, and approximate entropy. Furthermore, we will assess the somnolence, the risk of Obstructive Sleep Apnea Syndrome (OSAS), and the quality of sleep and life related to the health in these individuals through the application and analysis of specific questionnaires. The obtained results will be submitted to the statistical analysis using the Paired T-Test or Wilcoxon-Signed Rank Test, according to the distribution analysis of the data. (AU)