Efficacy of soft palatal augmentation prosthesis for oral functional rehabilitation in patients with dysarthria and dysphagia: a protocol for a randomised controlled trial.

INTRODUCTION: Palatal augmentation prosthesis (PAP) is used in patients with articulation and swallowing disorders caused by postoperative loss of tongue tissue due to tongue cancer, cerebrovascular disease sequelae and age-related hypofunction. We have previously reported a newly designed soft PAP fabricated using an thermoplastic material that is particularly appropriate for early intervention. However, the effect of soft PAP on oral function improvement remains to be elucidated. The aim of this study is to investigate whether soft PAP can improve dysarthria and dysphagia occurring as cerebrovascular disease sequelae. METHODS AND ANALYSIS: This prospective, randomised, controlled trial will compare the immediate and training effects of rehabilitation using soft PAP with those of rehabilitation without using it. Primary outcomes are the single-word intelligibility test score and pharyngeal transit time (PTT). Secondary outcomes are tongue function (evaluated based on maximum tongue pressure, repetitions of tongue pressure and endurance of tongue pressure), articulation function (evaluated based on speech intelligibility, oral diadochokinesis, Voice-Related Quality of Life (V-RQOL)) and swallowing function (evaluated using Eating Assessment Tool-10). The study results will help determine the efficacy of Soft PAP in improving functional outcomes of word intelligibility and PTT. We hypothesised that early rehabilitation using Soft PAP would more effectively improve articulation and swallowing function compared with conventional rehabilitation without using soft PAP. ETHICS AND DISSEMINATION: Ethical approval was obtained from the Okayama University Certified Review Board. The study findings will be published in an open access, peer-reviewed journal and presented at relevant conferences and research meetings. TRIAL REGISTRATION NUMBER: jRCTs062200054.

Possible involvement of neurons in locus coeruleus in inhibitory effect on glossopharyngeal expiratory activity in a neonatal rat brainstem-spinal cord preparation in vitro.

In this study, we found that a certain motor branch of glossopharyngeal (IX) motor nerves stably exhibits not only inspiratory activity but also expiratory activity with pons removal in neonatal rat brainstem-spinal cord preparations in vitro. Because this finding indicates that IX expiratory activity is masked by an inhibitory mechanism operating in the pons, we sought to determine the candidate neurons that exert an inhibitory effect on IX expiratory activity. IX expiratory activity was observed when only the pons was perfused with noradrenaline (NA) or clonidine (alpha2 adrenergic receptor agonist), but not when NA and yohimbine (alpha2 adrenergic receptor antagonist) were perfused together. IX expiratory activity was also observed following the removal of the dorsal pons but not the ventral pons. The local administration of clonidine into the bilateral locus coeruleus (LC) evoked burst discharges during the expiratory phase in the IX motor rootlet. These results suggest that neurons in the LC that possess an alpha2 adrenergic receptor on the membrane surface exert a tonic inhibitory effect on IX expiratory activity in neonatal rat brainstem-spinal cord preparations.