Key points

Introduction

To discuss rehabilitation of the irradiated larynx, a sound understanding of the physiology and function of the normal larynx and that of the irradiated larynx is required. These topics are covered elsewhere in this publication (see the articles by Niv Mor and Mauricio Gamez elsewhere in this issue). They serve as foundational building blocks for discussing behavioral, medical, and surgical intervention geared toward restoring the voice in the postradiation patient.

Radiation-induced dysphonia can develop after radiation therapy (RT) for a primary laryngeal cancer or when the larynx is in the radiation field for nonlaryngeal malignancy and cannot be, or is not, spared. Dysphonia related to radiation exposure appears to be dose dependent. In patients with nonlaryngeal primary head and neck malignancies, dysphonia becomes problematic when the dose to the larynx exceeds 50 Gy. This dose is less than the treatment dose for laryngeal primary malignancies, but the resultant rate of dysphonia at this level of radiation exposure is unknown. Radiation is often chosen as a treatment modality for early laryngeal primary squamous cell carcinoma (T1 or T2 disease) given its excellent cure rates but usually requires doses in excess of 65 Gy. Resultantly, between 14% and 92% of patients report dysphonia after radiotherapy for early laryngeal malignancies.

The timing of the development of dysphonia after RT is variable. Patients can present with dysphonia early during treatment or they may have initial improvement in their voice only to worsen 5 to 15 or more years after treatment; those with early onset can persist for years or may improve spontaneously. Acute voice changes stem from oxidative injury resulting in injury to both diseased and normal tissue; this can lead to mucosal edema and necrosis and resultant epithelial sloughing. As the acute phase subsides, a fibroblastic response develops, resulting in long-term deposition of collagen and fibrosis. Fibrosis leads to reduced tissue viscosity, which dampens the normal vibratory patterns that are required for normal voice. These tissue changes make rehabilitation difficult because there is currently no therapy that can improve the vibratory capacity of the vocal folds.

Because none of the treatment modalities have been clearly shown to help improve postradiation phonation, rehabilitation is often multifaceted, relying on both physician and speech-language pathologists to maximize outcomes. This article serves to first outline important factors in the evaluation of the patient and then discusses both surgical and nonsurgical interventions that may aid rehabilitation.

Introduction

To discuss rehabilitation of the irradiated larynx, a sound understanding of the physiology and function of the normal larynx and that of the irradiated larynx is required. These topics are covered elsewhere in this publication (see the articles by Niv Mor and Mauricio Gamez elsewhere in this issue). They serve as foundational building blocks for discussing behavioral, medical, and surgical intervention geared toward restoring the voice in the postradiation patient.

Radiation-induced dysphonia can develop after radiation therapy (RT) for a primary laryngeal cancer or when the larynx is in the radiation field for nonlaryngeal malignancy and cannot be, or is not, spared. Dysphonia related to radiation exposure appears to be dose dependent. In patients with nonlaryngeal primary head and neck malignancies, dysphonia becomes problematic when the dose to the larynx exceeds 50 Gy. This dose is less than the treatment dose for laryngeal primary malignancies, but the resultant rate of dysphonia at this level of radiation exposure is unknown. Radiation is often chosen as a treatment modality for early laryngeal primary squamous cell carcinoma (T1 or T2 disease) given its excellent cure rates but usually requires doses in excess of 65 Gy. Resultantly, between 14% and 92% of patients report dysphonia after radiotherapy for early laryngeal malignancies.

The timing of the development of dysphonia after RT is variable. Patients can present with dysphonia early during treatment or they may have initial improvement in their voice only to worsen 5 to 15 or more years after treatment; those with early onset can persist for years or may improve spontaneously. Acute voice changes stem from oxidative injury resulting in injury to both diseased and normal tissue; this can lead to mucosal edema and necrosis and resultant epithelial sloughing. As the acute phase subsides, a fibroblastic response develops, resulting in long-term deposition of collagen and fibrosis. Fibrosis leads to reduced tissue viscosity, which dampens the normal vibratory patterns that are required for normal voice. These tissue changes make rehabilitation difficult because there is currently no therapy that can improve the vibratory capacity of the vocal folds.

Because none of the treatment modalities have been clearly shown to help improve postradiation phonation, rehabilitation is often multifaceted, relying on both physician and speech-language pathologists to maximize outcomes. This article serves to first outline important factors in the evaluation of the patient and then discusses both surgical and nonsurgical interventions that may aid rehabilitation.

Patient evaluation overview

Evaluation begins with obtaining a thorough history and physical examination. Aspects of the patient’s history that are valuable for guiding treatment include staging of the primary malignancy, treatment course including radiation dose and completion date, response to treatment, antecedent voice concerns or disease, current vocal demand or vocal use, and current vocal concerns.

Many of these aspects can be identified with a review of the medical records from the treating radiation oncologist. A review of the initial staging can help the clinician appreciate the laryngeal subsite (supraglottic, glottic, or subglottic) of the primary tumor and the presence of nodal disease. This information will give the clinician an appreciation for both the anatomic focus of the radiation treatment and the size of the treatment fields if (ie, if radiation was also administered to neck disease). It will also allow the physician to focus their subsequent examinations to survey for recurrence or persistence of disease. A review of the treatment course is helpful to identify the total dose of radiation administered to the larynx and any breaks in treatment that could lead to higher concern for recurrence.

The patient’s vocal history should be elicited with a thorough interview before the physical examination. Key portions of the history include preradiation voice changes and whether there was change to the voice throughout RT. The patient’s current concerns should also be discussed and can highlight perceived changes in effort or strain of phonation, difficulty with projection, decreased pitch flexibility or loss of range, and breathiness. These concerns are discussed from a subjective perspective but can be quantified with the use of the Voice-Handicap Index (VHI) and the Voice-Related Quality of Life. These are completed by the patient and may be useful to quantify the patients’ experience and concerns to follow their progression over time.

Physical examination should include a full head and neck examination along with a thorough laryngeal examination and objective assessment of the quality of the patient’s voice. The vocal quality of the patient who has received radiation can vary dramatically from almost no deficits to complete aphonia, and a multidisciplinary approach incorporating physicians and speech-language pathologists should be used to fully assess the patient’s voice. For objective assessment of voice quality, either the GRBAS scale (Grade, Roughness, Breathiness, Aesthenia, Strain) or the CAPE-V (The Consensus Auditory-Perceptual Evaluation of Voice) scale can be used in objectifying the subjective perception of a patient’s voice. Both are useful for perceptual assessment of a patient’s voice but may not necessarily correlate to the patient’s self-assessment; however, the GRBAS and CAPE-V scales correlate to each other when graded by experienced speech-language pathologists.

Acoustic parameters are another means to obtain objective measures of vocal quality. Parameters measured include fundamental frequency and range, intensity, maximum phonation time, formant patterns, airway pressures, shimmer, jitter, signal-to-noise ratio, and cepstral peak prominence. When compared with patients who do not receive radiation, patients who do receive radiation have decreased intensity, pitch range, and maximum phonation time; they also demonstrate increased shimmer, jitter, and subglottic air pressure. Cepstral peak prominence is an objective measure that has recently shown strong correlations with other objective voice measures but also perceptual measures of voice changes. It has not been studied specifically in the irradiated larynx and is an area that will require focus for future research.

Visualization of the larynx should also be performed as part of the physical examination. Indirect mirror laryngoscopy can be effective in identifying large lesions of the larynx or vocal fold immobility but is incapable of identifying subtle mucosal lesions or vibratory abnormalities. Indirect transnasal fiberoptic laryngoscopy can be used when the patient’s gag reflex limits adequate visualization of the larynx with a mirror. This technique shares similar limitations as mirror laryngoscopy in that the provider may not identify small mucosal lesions or vibratory deficiencies. Indirect videostroboscopic visualization of the larynx is indicated to further examine the vibratory action of the vocal folds and affords the benefits of a magnified examination of the larynx. Whenever possible, recordings of voice samples and laryngeal examination should be archived to compare in future examinations.

Videostroboscopy is an incredible advancement in our ability to visualize subtle vibratory deficits created by RT, but it offers an incomplete visualization of the larynx. Videostroboscopy creates the illusion of vibration by capturing out-of-phase images and merging them together into a fluid video. In doing so, the technique omits segments of laryngeal motion and vibration when the light source is not active. High-speed cinematography captures 2000 to 6000 images per second and, therefore, captures the most images omitted by stroboscopy. Enormous amounts of video data are created for each examination, which can make interpretation and clinical application challenging. Videokymography and kymography are ancillary examinations that developed from high-speed cinematography and offer an assessment of the vocal fold mucosa of one narrow coronal plane of the vocal folds. This method allows the examiner to assess symmetry and amplitude of vibration at the selected point of the glottis. Videokymography is more prevalent of an instrument than kymography, but both techniques enrich the data offered by high-speed cinematography; they both show limited, but increasing, clinical application for laryngeal visualization.

Obtaining a thorough history and physical examination are necessary to help build a care plan tailored to the patient. The physician is only one part of this process, however. We find that a thorough interdisciplinary examination performed in concert with speech-language pathology is integral to furthering the identification of concerning objective and subjective patient concerns. We feel this approach offers the most comprehensive patient evaluation and maximizes the potential benefit of therapy.

Management goals

Although rehabilitation of the postradiation voice is important, the clinician must always be cognizant of the risk of persistence or recurrence of disease and the need for continued surveillance for secondary malignancies. Once absence of disease is confirmed through examination or ancillary imaging techniques, the goals of therapy are focused on the concerns of the patient. These can be specifically aimed at objective findings identified in clinical evaluation or subjective measures identified by the patient.