Improvement in Swallowing Function in Patients with Previous Irradiation for Nasopharyngeal Carcinoma by Expiratory Muscle Strength Training

Abstract

Dysphagia and chronic aspiration are common post-irradiation complications in nasopharyngeal carcinoma (NPC) survivors. Expiratory Muscle Strength Training (EMST) is a simple device-driven exercise therapy for swallowing training. This study investigates the effectiveness of EMST in a group of post-irradiated NPC patients. This prospective cohort, including twelve patients with previous irradiation for NPC and with swallowing disturbance, was performed between 2019 and 2021 in a single institution. Patients were trained with EMST for 8 weeks. Non-parametric analyses examined effects of EMST on primary outcome, maximum expiratory pressure. Secondary outcomes were measured with Penetration-aspiration scale, Yale pharyngeal residue severity rating scale (YPRSRS) by flexible endoscopic evaluation of swallowing, and Eating Assessment Tool (EAT-10) and M.D. Anderson Dysphagia Inventory questionnaire. Twelve patients, with a mean (SD) age of 64.3 (8.2) were recruited. There was no patient dropout with 88.9% overall compliance of training. Maximum expiratory pressure improved by 41% (median 94.5 to 133.5 cmH2O, p = 0.003). There was reduction in Penetration-aspiration scale with thin liquid (median 4 to 3, p = 0.026), and in YPRSRS at pyriform fossa with mildly thick liquid (p = 0.021) and at vallecula with thin liquid (p = 0.034), mildly thick liquid (p = 0.014) and pureed meat congee (p = 0.016). Questionnaire scores did not significantly change statistically. EMST is an easy-to-use and effective exercise therapy to improve airway safety and swallowing function in post-irradiated NPC survivors.

Keywords: Expiratory muscle strength training; Functional outcomes; Nasopharyngeal carcinoma; Swallowing.