Vocal fold masses are often complex in nature and can have a devastating result on the professional voice. These lesions are usually multifactorial with synergistic contributions over time from voice use demands and technique, medical conditions, medications, and the environment. General categories of benign vocal fold masses in professional voice include nodules, polyps, and cysts, but other pathology should be considered, such as reactive lesions, intracordal scarring, feeding varices, and reparative granuloma. A perspective on these issues is essential for proper diagnosis and management. Video procedures for nodule and polyp surgery accompany this content online.
Although many performers consider vocal fold masses, such as nodules, the bane of their existence, it is rare that these lesions are true career-breakers. It is essential, however, that the many issues contributing to the development of these lesions be identified and a multidisciplinary approach instituted to obtain the best possible and most consistent outcome. In the context of the professional voice, lesions are generally benign and inflammatory, but professional voice users often engage in carcinogenic activities, such as smoking, alcohol abuse, and use or abuse of recreational drugs. Such behaviors increase the risk for malignancies and the possibility of such cannot be overlooked. Also, the title of this article, vocal fold masses, has been chosen to reinforce the concept that these inflammatory conditions add weight to the vocal folds and impair vocal closure. This article reviews the multifactorial contributions to voice disorders with emphasis on the pathophysiology of vocal masses, describes the resulting effects on voice function, and elaborates on the types of masses encountered in professional voice users.
Multifactorial contributions to developing vocal masses
Voice use demands (overuse) and vocal technique (misuse) are central to the trauma and pathogenesis of vocal fold masses in professional voice users. Common to performers and other professionals is a passion for communication that often pushes the scope of voice use relating to amount of time, intensity, frequency of use, vocal range, and more advanced techniques. Young performers, in particular, usually use their voices in many different roles that include self-management and day jobs also requiring their voices. The blossoming use of cellular telephones, especially in loud public environments, significantly adds to this sustained and repetitive vocal trauma. Trauma and subsequent inflammation manifest as vocal limitations that frustrate the professional voice user, and there is a tendency to try to exceed these limitations.
Paying tribute to these personality factors in the pathogenesis of nodules and polyps, Yano and colleagues 1982 recognized significantly higher extroversion scores on Maudsley Personality Inventory in these patients. More recently, Roy and colleagues used the Multidimensional Personality Questionnaire to evaluate personality features distinct to functional dysphonia and those who have vocal nodules. They determined that the functional dysphonia group was introverted, stress-reactive, alienated, and unhappy. In contrast, the vocal nodules group was considered to be socially dominant, stress-reactive, aggressive, and impulsive.
Based on the multifactorial nature of voice disorders, underlying medical conditions, medications, and the environment add to the synergy in pathogenesis of vocal fold masses. With the larynx at the epicenter, the significant interrelations of the respiratory and upper gastrointestinal tracts also predispose the vocal folds to further damage. These contributing diseases include rhinitis, allergy, sinusitis, asthma, bronchitis, laryngopharyngeal reflux, and others discussed elsewhere in this issue. Environmental factors include allergens, dust and other particulates, tobacco smoke, and a host of occupational irritants.
Principal to medical conditions that contribute to inflammatory vocal lesions is laryngopharyngeal reflux (LPR). There are many examples in the literature; Kuhn and colleagues studied 11 patients who had vocal nodules using 24-hour simultaneous three-site pharyngoesophageal pH monitoring. They found pharyngeal acid reflux events in 7 patients in that 24-hour period (one to four episodes) compared with 2 of 11 controls studied (one to two episodes). In a follow-up study by Ulualp and colleagues , 9 patients who had vocal nodules and posterior laryngitis underwent similar evaluation, in which 78% were found to have pharyngeal acid reflux (significantly higher than controls). It is believed that the baseline inflammation resulting from LPR episodes predisposes the vocal folds to the stresses from vocal overuse and misuse.
In a series of allergy patients who had laryngeal disease, Hocevar-Boltezar and colleagues found that treatment of 70 patients who had laryngitis and positive allergy skin tests resulted in an improved outcome compared with 5 patients who did not receive treatment, suggesting that hypersensitivity to inhalatory and nutritional allergens makes laryngeal mucosa more susceptible to the adverse action of other factors. This example also reinforces the synergistic effects contributing to the development of vocal fold masses.
Pathophysiology, shearing stress, and compensation
Because vocal overuse and misuse are central to the development of vocal fold masses, it is important to understand how biomechanical factors work on the membranous vocal folds to produce such lesions. Jiang and colleagues developed a mathematical computer-based model to describe the vibratory response of the vocal folds during phonation using the finite element method. They found that in normal phonation, mechanical stress was the least at the midpoint of the membranous vocal fold and highest at tendon attachments. In contrast, during hyperfunctional dysphonia there was an increase in the second mode of vibration, resulting in incomplete approximation of the vocal folds posteriorly and increased stress at the location between vibratory segments. In other words, when there was increased stiffness in the body of the vocal folds, the midpoint of the membranous vocal folds encountered higher shearing stresses.
Furthermore, when there was already a nodule or mass, it produced a high mechanical stress at its base during vibration. The authors concluded that intraepithelial stress plays an important role in the pathogenesis of nodules and other masses, and that an abnormal vibratory mode may be more damaging than a high intensity of vibration .
In a follow-up study using a self-oscillating model, mechanical stress was noted to periodically undulate with the vibration of the vocal folds, and that vocal impact caused a jump in the normal stress value . The model was also able to confirm that stress was significantly higher on the surface of the vocal folds compared with that under the surface. These models reinforce the concept of how vocal impact results in vibratory trauma to the vocal folds, and that stresses are compounded once a lesion is present.
Many lesions can result (at least in part) from this process, including nodules, polyps, and cysts, but other pathology should be considered, such as reactive lesions, intracordal scarring, feeding varices, and reparative granuloma. The direct effect of the vocal mass is to add weight to the vocal fold, which decreases its vibratory qualities and frequency as demonstrated on strobolaryngoscopy. There is a clinical decrease in phonatory pitch along with an abbreviated pitch range, as demonstrated on voice function testing. The presence of the mass causes impaired vocal phase closure during phonation, resulting in excess air egress. Clinically, this adds to a breathy quality of the voice, but also contributes to vocal fatigue. Disruption of vocal fold vibration and phase closure often leads to phase asymmetry (depending on the specific lesion), which adds to a grainy quality of the voice.
At this point in the development of the vocal mass, there is a self-perpetuating cycle of inflammation and trauma. Although behavioral qualities contribute to the initial vocal trauma that leads to the development of this process, the presence of a lesion can result in compensatory muscle tension in an effort to reduce excess air flow through the glottis. Altman and colleagues reviewed 150 patients who had muscle tension dysphonia, in which 34 had polyps, 20 had nodules, and 12 had vocal cysts. They found a significant degree of compensatory muscle hyperconstriction in this population. Nevertheless, the multifactorial contributions and spectrum of lesions that may result emphasize the importance of strobolaryngoscopy in assessment and multidisciplinary approach with speech and voice therapy, medical, and surgical options.
Pathophysiology, shearing stress, and compensation
Because vocal overuse and misuse are central to the development of vocal fold masses, it is important to understand how biomechanical factors work on the membranous vocal folds to produce such lesions. Jiang and colleagues developed a mathematical computer-based model to describe the vibratory response of the vocal folds during phonation using the finite element method. They found that in normal phonation, mechanical stress was the least at the midpoint of the membranous vocal fold and highest at tendon attachments. In contrast, during hyperfunctional dysphonia there was an increase in the second mode of vibration, resulting in incomplete approximation of the vocal folds posteriorly and increased stress at the location between vibratory segments. In other words, when there was increased stiffness in the body of the vocal folds, the midpoint of the membranous vocal folds encountered higher shearing stresses.
Furthermore, when there was already a nodule or mass, it produced a high mechanical stress at its base during vibration. The authors concluded that intraepithelial stress plays an important role in the pathogenesis of nodules and other masses, and that an abnormal vibratory mode may be more damaging than a high intensity of vibration .
In a follow-up study using a self-oscillating model, mechanical stress was noted to periodically undulate with the vibration of the vocal folds, and that vocal impact caused a jump in the normal stress value . The model was also able to confirm that stress was significantly higher on the surface of the vocal folds compared with that under the surface. These models reinforce the concept of how vocal impact results in vibratory trauma to the vocal folds, and that stresses are compounded once a lesion is present.
Many lesions can result (at least in part) from this process, including nodules, polyps, and cysts, but other pathology should be considered, such as reactive lesions, intracordal scarring, feeding varices, and reparative granuloma. The direct effect of the vocal mass is to add weight to the vocal fold, which decreases its vibratory qualities and frequency as demonstrated on strobolaryngoscopy. There is a clinical decrease in phonatory pitch along with an abbreviated pitch range, as demonstrated on voice function testing. The presence of the mass causes impaired vocal phase closure during phonation, resulting in excess air egress. Clinically, this adds to a breathy quality of the voice, but also contributes to vocal fatigue. Disruption of vocal fold vibration and phase closure often leads to phase asymmetry (depending on the specific lesion), which adds to a grainy quality of the voice.
At this point in the development of the vocal mass, there is a self-perpetuating cycle of inflammation and trauma. Although behavioral qualities contribute to the initial vocal trauma that leads to the development of this process, the presence of a lesion can result in compensatory muscle tension in an effort to reduce excess air flow through the glottis. Altman and colleagues reviewed 150 patients who had muscle tension dysphonia, in which 34 had polyps, 20 had nodules, and 12 had vocal cysts. They found a significant degree of compensatory muscle hyperconstriction in this population. Nevertheless, the multifactorial contributions and spectrum of lesions that may result emphasize the importance of strobolaryngoscopy in assessment and multidisciplinary approach with speech and voice therapy, medical, and surgical options.
Prevalence of vocal masses and dysphonia in voice professionals
Teachers are perhaps the largest group of voice professionals who seem to be at higher risk for the development of hoarseness and vocal masses. Sulkowski and Kowalska analyzed 1261 cases of occupational voice disorders referred for otolaryngologic evaluation in Poland over a 5-year period. Some 66% of these patients were primary school teachers, and 55% of referrals were 51 to 60 years of age. Overall, vocal nodules were found in 4.2%. In a Finnish study, Smolander and Huttunen surveyed 181 teachers, of whom 42% reported frequent voice symptoms, and 10% had history of vocal nodules.
Because the evolution of these lesions is complex and the laryngologist initially evaluates patients after they have experienced voice limitations over a period of time, it is uncommon to have an isolated lesion without concomitant or confounding findings. Similarly, nodules are often a “wastebasket” diagnosis for those clinicians unskilled to differentiate between nodules, polyps, cysts, reactive lesions, and intracordal scarring. Although it may be a matter of semantics what to name a lesion, the description is nevertheless helpful in considering prognosis and therapeutic plan.
Nagata and colleagues reviewed their 10-year experience with 1156 patients and found 372 who had nodules and 784 who had polyps. Sataloff and colleagues reviewed their experience with videostroboscopy on 377 patients and found nodules in 32, polyps in 4, cysts in 8, granulomas in 3, Reinke edema in 4, and scar in 32. An in-depth discussion of these vocal fold masses follows. Discussion about each of these masses follows with relevance to diagnosis and prognosis.
Nodules
Vocal nodules are defined as bilateral symmetric epithelial swelling of the anterior/mid third of the true vocal folds.
(Access Video on Nodules in online version of this article at: http://www.Oto.TheClinics.com .)
Demographically, these are seen in children, adolescents, and predominantly female adults working in professions with high voice demands. Sarfati evaluated 90 French teachers referred for vocal disorders, and pathology was found in two thirds overall, with pseudocysts or nodules in one third overall.
De Bodt and colleagues characterized evolution of these nodules from childhood to adolescence. They examined a group of 34 post-mutational adolescents who had a prior diagnosis of vocal fold nodules. These nodules were still present in 47% of girls but only 7% of boys. The degree of dysphonia in childhood and the presence of allergy were also predictors of persisting voice complaints in adolescence. This study reinforces multifactorial contributions to the development of these lesions, including behavior. The female preponderance from childhood to adolescence, coupled with adult female preponderance in other studies, further confirms that females are at particular risk. Perhaps the softer intensity of female voices leads to more hyperfunction in adult professional environments with louder background noise.
One additional note is made of preponderance of nodules in patients who have congenital microweb. Ruiz and colleagues reviewed a sample of 107 patients who had vocal nodules and recognized microweb in 9.4%, although the presence of microweb did not affect nodule location. Although this is a small portion of those patients who develop nodules, it does imply that the clinician should have a heightened awareness of the presence of microwebs, which may have additional implications of treatment and prognosis.
The pathophysiology of vocal nodules relies on the mid-membranous vocal fold experiencing maximal shearing and collision forces. This location corresponds to the junction of the anterior to middle vocal folds (because the posterior third of the vocal folds is coupled to the vocal process of the arytenoids). This repeated collision initially results in localized vascular congestion with edema. Eventually hyalinization of Reinke space with thickening of overlying epithelium occurs with the development of epithelial hyperplasia.
Consequently, the histology of nodules is distinct from polyps and other vocal lesions. Kotby and colleagues collected 11 patients who had nodules (all female) to characterize this histology. Nodules are generally acellular, with thickening of epithelium over a matrix with abundant fibrin and organized collagen. Polyps also have a more pronounced epithelial reaction and a more dense fibrous stroma than polyps. Immunohistochemical characterization of nodules reveals a thickened basement membrane zone rich in collagen type IV and more intense fibronectin staining .
Patients who have vocal nodules present with chronic hoarseness, often with repeated episodes of more severe voice loss. Singers may complain of a loss of ability to sing high notes softly, with frequent voice breaks, increased breathiness, and vocal fatigue. Strobolaryngoscopy reveals bilateral symmetric superficial swelling of the vocal folds at the striking zone junction of the anterior to middle thirds ( Fig. 1 A). There is slightly decreased amplitude of the mucosal wave, but the wave is generally symmetric. Because there is hourglass-shaped glottal closure, there is consequently decreased phase closure ( Fig. 1 B).
The mucus layer on the surface of the vocal folds is also important for lubrication and reducing friction. Patients who have vocal nodules may subsequently have irregular vibration of the surface mucus layer, perhaps resulting in drying, leading to impaired lubrication and an exacerbation of the surface stresses leading to the formation of nodules . In addition, abnormal or excess mucus has been anecdotally noted by the author to be responsible for increased voice breaks in singers when transitioning through the passaggio (ascending glissando from the chest voice into the head voice).
When considering treatment options for a patient who has vocal nodules, it is useful to discuss with the patient a simple analogy of a carpenter using a hammer over a long period of time without gloves. As a result, calluses form at the areas of maximal impact with the hand. Using this analogy, one may expect that conservative (nonsurgical) treatment would be applicable to the patient who has true vocal nodules.
Hogikyan and colleagues recognized a consensus among otolaryngologists, speech pathologists, and teachers of singing regarding the treatment of singers who have nodules. Addressing voice use demands, improper technique, optimizing other contributing factors, and coordinating care were believed to be paramount.
Indications for microsurgical treatment include longstanding nodules, particularly when other factors, including speech therapy, have been maximized, and suspicion of a primary lesion with a reactive callus on the other vocal fold. Microsurgical technique is addressed elsewhere; it is imperative to preserve normal anatomy, keeping the plane of dissection superficial, and to minimize trauma to the lamina propria.
Polyps
Vocal polyps are unilateral, occasionally pedunculated masses encountered on the true vocal fold. They occur more often in males, after intense intermittent voice abuse, history of aspirin or anticoagulant use, or other vocal trauma, such as endotracheal intubation. Kotby and colleagues reviewed 19 patients who had polyps, of whom 16 (84%) were male. The pathophysiology is believed to be attributable to breakage of a capillary in Reinke space (superficial lamina propria) with subsequent extravasation of blood, resultant local edema, and ultimate organization with hyalinized stroma.
The resulting mass may be broad-based or pedunculated, and hemorrhagic versus nonhemorrhagic ( Fig. 2 ).
