Changes in laryngeal sensation evaluated with a new method before and after radiotherapy

Radiotherapy of the laryngopharynx sometimes leads to functional disabilities including swallowing dysfunction. One of the reasons for these disabilities is a deterioration of laryngeal sensation. Laryngeal sensation is an important factor in swallowing, but quantitative evaluation of laryngeal sensation has been difficult. In this study, we evaluated changes in laryngeal sensation before and after radiotherapy for laryngeal and hypopharyngeal cancer, using a flexible laryngoscope and probes. This study was conducted in 12 patients, 8 with laryngeal cancer and 4 with hypopharyngeal cancer, who received radiotherapy alone or chemoradiotherapy at our medical centre. Measurements were performed using a 3.3-mm-diameter flexible laryngoscope with a probe port and four types of probes with 0.06-, 0.13-, 0.20-, and 0.30-mm nylon filaments attached to a wire tip. Sensation was evaluated at the tip of the epiglottis and the arytenoid region. Measurements were performed before radiotherapy, 1, 3 months, and 1 year after completion of radiotherapy. Sensation of the epiglottis and arytenoid deteriorated significantly 1 and 3 months after radiotherapy compared with before radiotherapy. Laryngeal sensation recovered in most cases within 1 year after radiotherapy. The present study clearly demonstrates the deterioration of laryngeal sensation with radiotherapy.