Objective: The larynx may receive high doses of radiation even in the absence of disease. Preliminary investigation has provided evidence that significant voice alterations exist in patients who received radiotherapy (RT) for non-laryngeal tumors of the head and neck. This study evaluates subjective and objective parameters of vocal function in this patient population compared with a control group of patients irradiated for early glottic tumors.
Study design: Retrospective cohort study.
Methods: Vocal function in patients irradiated for non-laryngeal and early glottic tumors was assessed in a comprehensive manner and compared. Microanalytical and macroanalytical acoustic analyses, aerodynamic measurements, and videostroboscopy were performed on vowel production data. The Voice Handicap Index was administered for self-assessment of voice quality. All subjects were male, smokers, and greater than 12 months post-RT.
Results: Seventeen patients with non-laryngeal tumors and 13 patients with early glottic tumors were evaluated. Microanalytical acoustic parameters were worse for 75% (6 of 8) of the acoustic measures of vowel production in the non-laryngeal group. These include jitter, relative amplitude perturbation, amplitude perturbation quotient, normalized noise energy, pitch amplitude, and spectral flatness ratio. Macroanalytical acoustic analyses revealed no difference in fundamental frequency but numerically smaller phonational frequency range in the non-laryngeal group. All aerodynamic measures, including mean phonation time, mean airflow, and vocal fold diadochokinetic rate, were decreased in the non-laryngeal group. Videostroboscopy demonstrated increased supraglottic activity in the non-laryngeal group. Voice handicap was significantly greater in the non-laryngeal group.
Conclusions: When compared with patients receiving RT for early glottic tumors, there is objective and subjective evidence of vocal dysfunction in patients treated with wide-field RT for non-laryngeal tumors.