The characteristics of the surface electromyographic signals recorded from submental and infrahyoid muscles when swallowing in patients with nasopharyngeal carcinoma after radiotherapy

Objective To study the surface electromyographic signal characteristics of submental and infrahyoid muscles when swallowing in patients with nasopharyngeal carcinoma (NPC) following radiotherapy. Methods Fifteen post-radiotherapy NPC patients with pharyngeal dysphagia confirmed by videofluoroscopie swallowing study (VFSS) were selected into the patient group, while another 15 healthy subjects were recruited into the healthy group. Surface electomyography (sEMG) was used to collect sEMG signals from submental muscles and infrahyoid muscles during both dry and 3 ml thick liquid swallowing, and sEMG duration, average amplitude and peak amplitude para-meters were compared between the two groups. Results Compared with healthy subjects, the patient group showed significantly longer sEMG duration of submental muscles and infrahyoid muscles during dry swallowing and 3 ml thick liquid swallowing (P<0.05). Moreover, significantly longer sEMG duration of submental muscles and infrahyoid muscles was observed when swallowing 3 ml thick liquid, compared with dry swallowing (P<0.05). The average sEMG amplitude and peak amplitude of submental muscles and infrahyoid muscles of patients when dry swallowing and 3 ml thick liquid swallowing were both significantly higher than those of healthy subjects (P<0.05). Conclusion Submental muscles and infrahyoid muscles manifested enhanced contractions during swallowing in NPC patients with dysphagia, which played a compensatory role after radiotherapy. Key words: Surface electromyography; Dysphagia; Nasopharyngeal carcinoma