Introduction We evaluated the feasibility and impact of Expiratory Muscle Strength Training (EMST) on respiratory and bulbar function in persons with amyotrophic lateral sclerosis (ALS). Methods 25 ALS patients participated in this delayed intervention open-label clinical trial. Following a lead-in period, patients completed a 5-week EMST protocol. Outcome measures included: maximum expiratory pressure (MEP), physiologic measures of swallow and cough, and Penetration-Aspiration Scale (PAS) scores. Results Of those participants who entered the active phase of the study (n=15), EMST was well tolerated and led to significant increases in MEPs and maximum hyoid displacement during swallowing post-EMST (P<0.05). No significant differences were observed for PAS scores or cough spirometry measures. Discussion EMST was feasible and well tolerated in this small cohort of ALS patients and led to improvements in expiratory force-generating pressures and swallow kinematics. Further investigation is warranted to confirm these preliminary findings.

Individuals with UVFI of iatrogenic and idiopathic etiologies with subjective dysphagia demonstrate objective evidence of pharyngeal weakness. The increased prevalence of aspiration in this population may not be solely the result of impaired airway protection.

The most common causes of dysphagia in a tertiary-care swallowing center are reflux, postirradiation dysphagia, and cricopharyngeus muscle dysfunction. A precise cause for the symptom could not be identified in 13% of our cohort. Endoscopic visualization (laryngoscopy, flexible endoscopic evaluation of swallowing, and transnasal esophagoscopy) and fluoroscopic swallow studies were the investigations most often utilized. These techniques can be used to arrive at a diagnosis in 80% of cases.

The laryngeal adductor reflex (LAR) is an involuntary protective response to stimuli in the larynx. The superior laryngeal nerve (SLN) acts as the afferent limb and the recurrent laryngeal nerve (RLN) as the efferent limb of this reflex, which is modulated by the central nervous system. Perhaps the most clinically significant application of the LAR is its use in laryngopharyngeal (LP) sensory discrimination testing. Importantly, aberrations in the LAR may predict dysphagia or portend clinical phenotypes of chronic cough, vocal cord dysfunction or pediatric apneas. LP sensation is a potential target for interventions addressing the aforementioned conditions though currently remains an area of active investigation.

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