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Week 5 – Draft your article (due 2016-10-24)
Vocal fold nodules are bilaterally symmetrical benign whitish masses that form at the midpoint of the vocal folds (A). Although diagnosis involves a physical examination of the head and neck, as well as perceptual voice measures (B), visualization of the vocal nodules via laryngeal endoscopy remains the primary diagnostic method (C).
Vocal fold nodules interfere with the vibratory characteristics of the vocal folds (1,2) by increasing their mass (2) and changing the configuration of the vocal fold closure pattern (1,2,3). Due to these changes, the quality of the voice may be affected (1). As such, the major perceptual signs of vocal fold nodules include vocal hoarseness and breathiness (2,4). Other common symptoms include increased phonatory effort (1), vocal fatigue (1,4), soreness or pain lateral to the larynx, and reduced frequency and intensity range (1,2). Airflow levels during speech may also be increased (1).
Vocal fold nodules are thought to be the result of vocal fold tissue trauma caused by excessive mechanical stress (1,3,4). This may be the result of repeated or chronic vocal overuse, abuse, or misuse (4). Predisposing factors include profession (1), gender (3), dehydration, respiratory infection, and other inflammatory factors (1).
For professional voice users as well as individuals who frequently experience hoarseness, vocal hygiene practices are recommended for the prevention of vocal fold nodules and other voice disorders.[1] Vocal hygiene practices include four components: regulating the quantity and quality of voice use, reducing phonotraumatic practices, improving vocal fold hydration, and eliminating behaviours that jeopardize vocal health.[1]
Treatment of vocal fold nodules usually involves behavioural intervention therapy administered by a speech-language pathologist. The prognosis for vocal fold nodules is good, as most respond well to these non-surgical techniques (behaviour modification)[2]. In severe cases, surgery to remove the lesions is recommended for best prognosis.[3][4] In children, nodules are more common in males, however in adulthood they are more common in females.[5] The exact prevalence of vocal fold nodules is not known, however high rates are reported in teachers.[2]
Pathophysiology
Vocal fold nodules often alter the mechanical properties of the vocal folds, which can interfere with their vibratory characteristics[1][2] (1, 4). Nodules may increase the mass of the vocal folds, especially along the medial edge where they are typically found[2] (4). This increased mass may result in aperiodic or irregular vibration, the perception of greater pitch and loudness perturbations, and of increased hoarseness[2] (4). Nodules may also affect the mucosal wave of the vocal folds by changing the configuration of the vocal fold closure pattern[1][3][2](1, 2, 4). They often cause incomplete closure of the vocal folds, resulting in an hourglass configuration[1][3][2] (1,2,4). The incomplete closure allows more air to escape through the vocal folds, which often results in the perception of breathiness[1][3] (1, 2). However, it should be noted that the degree to which nodules will affect the mucosal wave and vibratory characteristics of the vocal folds depends highly on the size of the nodule[1][3] (1, 2). Smaller nodules may still allow the vocal folds to achieve complete closure[1] (1).
Signs and symptoms
Perceptual signs and symptoms
One of the major perceptual signs of vocal fold nodules is a change in the quality of the voice[1] (1). The voice may be perceived as hoarse[2][4] (3, 4), due to aperiodic vibrations of the vocal folds (4), and may also be perceived as breathy[2][4] (3, 4), due to an incomplete closure of the vocal folds upon phonation[1][2] (1, 4). The degree of hoarseness and breathiness perceived may vary in severity. This variability may be due to the size and firmness of the nodules[2] (4). Other common symptoms include difficulty producing vocal pitches in the higher range[1][4][2] (1,3,4), increased phonatory effort[1] (1), and vocal fatigue[1][4] (1,3). There may be a sensation of soreness or pain in the neck, lateral to the larynx[1][2] (1,4), which generally occurs because of the increased effort needed to produce the voice[1] (1).
Acoustic signs
Major acoustic signs of vocal fold nodules involve changes in the frequency and the intensity of the voice. The fundamental frequency, an acoustic measure of voice pitch, may be normal. However, the range of pitches the individual is capable of producing may be reduced[1][2] (1,4), and it may be especially difficult to produce pitches in the higher range[1][4][2] (1,3,4). The intensity of the voice, an acoustic measure of amplitude or loudness, may also be normal[1] (1). However, the individual's amplitude range may be reduced as well[1][2] (1,4). Perturbations or variations in frequency, known as jitter, and in amplitude, known as shimmer, may be increased[2] (4).
Aerodynamic signs
If the nodules affect the closure of the vocal folds, airflow levels during speech may be increased in comparison to the speaker’s habitual levels. However, airflow levels may still fall within the upper limits of the normal range[1] (1). The degree to which an individual’s airflow levels increase seems to depend on the severity of the injury [2](4). Subglottal pressure, the air pressure that is available below the glottis and in the trachea to produce speech, may be increased as well[2] (4).
Causes
Vocal fold nodules are thought to be the result of vocal fold tissue trauma caused by excessive mechanical stress[1][3][4] (1,2,3). During phonation, the vocal folds undergo many forms of mechanical stress. One example of such stress is the impact stress caused by the collision between the left and right vocal fold surfaces during vibration[3] (2). This stress is thought to reach its maximum in the mid-membranous region of the vocal folds, a common site of nodule formation[3][4](2, 3). Vocal overuse (speaking for long periods), abuse (yelling), or misuse (hyperfunction) may produce excessive amounts of mechanical stress by increasing the rate and/or force with which the vocal folds collide. This may lead to trauma that is focalized to the mid-membranous vocal fold[4] (3) and subsequent wound formation[3] (2). Repeated or chronic mechanical stress is thought to lead to the remodeling of the superficial layer of the lamina propria[4] (3). It is this process of tissue remodeling that results in the formation of benign lesions of the vocal folds such as nodules[3][4] (2,3). There are several factors that may predispose an individual to vocal fold nodules. Activities or professions that may contribute to phonotraumatic behaviors include cheerleading, untrained singing, speaking above noise, and teaching without voice amplification, as these increase mechanical stress and subsequent vocal fold trauma[1] (1). Gender may be another predisposing factor, as vocal fold nodules occur more frequently in females[4] (3). The presence of dehydration, respiratory infection, and inflammatory factors may also act as predisposing or aggravating factors. Inflammatory factors may include allergies, tobacco and alcohol use, laryngopharyngeal reflux, and other environmental influences[1](1).
- ^ ISBN 0-8058-5631-5.
- ^ ISBN 0-7817-4239-0.
- ^ a b c d e f g h i Johns, M.M. "Update on the ethology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts". Current Opinion in Otolaryngology & Head and Neck Surgery. 11.
- ^ a b c d e f g h i j k Kunduk, M.; McWhorter, A.J. "True vocal fold nodules: The role of differential diagnosis". Current Opinion in Otolaryngology & Head and Neck Surgery. 17.