ABSTRACT
Purpose: Down syndrome (DS) is a developmental disability associated with difficulties in deglutition. The adult Ts65Dn mouse model of DS has been previously shown to have differences in measures of swallowing compared with euploid controls. However, the putative mechanisms of these differences in swallowing function are unclear. This study tested the hypothesis that the Ts65Dn genotype is associated with atypical measures of tongue muscle contractile properties, coinciding with atypical swallow function. Methods: Adult (5-month-old) Ts65Dn (n = 15 female, 14 male) and euploid sibling controls (n = 16 female, 14 male) were evaluated through videofluoroscopy swallow studies (VFSS) to quantify measures of swallowing performance including swallow rate and inter-swallow interval (ISI). After VFSS, retrusive tongue muscle contractile properties, including measures of muscle fatigue, were determined using bilateral hypoglossal nerve stimulation. Results: The Ts65Dn group had significantly slower swallow rates, significantly greater ISI times, significantly slower rates of tongue force development, and significantly greater levels of tongue muscle fatigue, with lower retrusive tongue forces than controls in fatigue conditions. Conclusion: Tongue muscle contractile properties are altered in adult Ts65Dn and coincide with altered swallow function.
ABSTRACT
INTRODUCTION: Preterm infants demonstrate problems with pharyngeal swallowing in addition to sucking problems. Oral motor intervention and nonnutritive sucking (NNS) were introduced for promoting oral feeding skills in preterm infants. NNS cannot cover all the components of oral feeding. In another hand, the swallowing exercise (SE) can accelerate the attainment of independent oral feeding in the preterm infants. The current study sought to examine if a combined program of NNS and SE compared with a program that only involves NNS would be more effective on oral feeding readiness of premature infants. MATERIAL AND METHODS: This randomized controlled trial was conducted in a neonatal intensive care unit (NICU). 45 preterm infants were recruited in three groups. In the group I, infants were provided with NNS twice a day. The group II received a program that involved 15 min of NNS and 15 min of SE, daily. Both interventions were provided 10 days during two consecutive weeks. The group III, control group, just received the routine NICU care. All infants were assessed by functional oral feeding outcome measures including postmenstrual age (PMA) at the start of oral feeding, PMA at full oral feeding, transition time (days from start to full oral feeding), PMA at discharge time and also the infant's dependency on tube-feeding at discharge time after interventions. Also, all infants were assessed via Preterm Oral Feeding Readiness Scale (POFRAS) before and after intervention. RESULTS: No significant differences were observed in the PMA mean at start of oral-feeding (P = 0.29), full oral-feeding (P = 0.13), discharge time (P = 0.45) and the mean of transition time (P = 0.14). Compared to the control group, more infants in the group II were discharged without tube-feeding (P = 0.01). The mean of POFRAS was significantly higher in both groups I and II compared to the group III (P = 0.02 and P = 0.01, respectively). This score was, however, not statistically different between the groups I and II (P = 0.98). CONCLUSIONS: Both studied interventions were superior to routine NICU care in enhancing the oral feeding readiness of preterm infants based on the POFRAS score. The studied combined program of NNS and SE, and not NNS program, could significantly increase the number of discharged infants without tube-feeding compared to control group.
