Vocal cord nodule

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Vocal voice nodule
Other namesVocal fold nodules, Vocal nodules
Specialty Otorhinolaryngology   OOjs UI icon edit-ltr-progressive.svg

Vocal cord nodules are bilaterally symmetrical benign white masses that form at the midpoint of the vocal folds. [1] Although diagnosis involves a physical examination of the head and neck, as well as perceptual voice measures, visualization of the vocal nodules via laryngeal endoscopy remains the primary diagnostic method. [2] [3] Vocal fold nodules interfere with the vibratory characteristics of the vocal folds by increasing the mass of the vocal folds and changing the configuration of the vocal fold closure pattern. [1] [2] [4] 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. [4] [5] Other common symptoms include vocal fatigue, soreness or pain lateral to the larynx, and reduced frequency and intensity range. [1] [4] [5] 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, including repeated or chronic vocal overuse, abuse, or misuse. [1] [2] [5] Predisposing factors include profession, gender, dehydration, respiratory infection, and other inflammatory factors. [1] [2]

Contents

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. [6] Vocal hygiene practices include three components: regulating the quantity and quality of voice use, improving vocal fold hydration, and reducing behaviours that jeopardize vocal health. [6] About 10% of nodules resolve on their own, which is more likely if they are smaller and the onset more recent. [7] Treatment of vocal fold nodules usually involves behavioural intervention therapy administered by a speech–language pathologist. In severe cases, surgery to remove the lesions is recommended for best prognosis. [8] [9] In children, vocal fold nodules are more common in males; in adults, they are more common in females. [10] [5]

Signs and symptoms

One of the major perceptual signs of vocal fold nodules is a change in the quality of the voice. [1] The voice may be perceived as hoarse, [4] [5] due to aperiodic vibrations of the vocal folds, [5] and may also be perceived as breathy, [4] [5] due to an incomplete closure of the vocal folds upon phonation. [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. [4] Other common symptoms include difficulty producing vocal pitches in the higher range, [1] [4] [5] increased phonatory effort, [1] and vocal fatigue. [1] [5] There may be a sensation of soreness or pain in the neck, lateral to the larynx, [1] [4] which generally occurs because of the increased effort needed to produce the voice. [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] [4] and it may be especially difficult to produce pitches in the higher range. [1] [4] [5] The intensity of the voice, an acoustic measure of amplitude or loudness, may also be normal. [1] However, the individual's amplitude range may be reduced as well. [1] [4] Perturbations or variations in frequency, known as jitter, and in amplitude, known as shimmer, may be increased. [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] The degree to which an individual's airflow levels increase seems to depend on the severity of the injury. Subglottal pressure, the air pressure that is available below the glottis and in the trachea to produce speech, may be increased as well. [4]

Causes

Vocal fold nodules are thought to be the result of vocal fold tissue trauma caused by excessive mechanical stress. [1] [2] [5] 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. [2] This stress is thought to reach its maximum in the mid-membranous region of the vocal folds, at the junction of the anterior 1/3rd and posterior 2/3rd, the most common site of nodule formation. [2] [5] 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 [5] and subsequent wound formation. [2] Repeated or chronic mechanical stress is thought to lead to the remodeling of the superficial layer of the lamina propria. [5] It is this process of tissue remodeling that results in the formation of benign lesions of the vocal folds such as nodules. [2] [5]

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] Gender may be another predisposing factor, as vocal fold nodules occur more frequently in females. [5] 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]

Pathophysiology

Vocal fold nodules often alter the mechanical properties of the vocal folds, which can interfere with their vibratory characteristics. [1] [4] Nodules may increase the mass of the vocal folds, especially along the medial edge where they are typically found. This increased mass may result in aperiodic or irregular vibration, the perception of greater pitch and loudness perturbations, and of increased hoarseness. [4] Nodules may also affect the mucosal wave of the vocal folds by changing the configuration of the vocal fold closure pattern. They often cause incomplete closure of the vocal folds, resulting in an hourglass configuration. [1] [2] [4] The incomplete closure allows more air to escape through the vocal folds, which often results in the perception of breathiness. [1] [2] 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] [2] Smaller nodules may still allow the vocal folds to achieve complete closure. [1]

Diagnosis

Diagnosing vocal fold nodules typically includes a comprehensive analysis of medical and voice history, a physical examination of the head and neck, perceptual evaluation of voice, and visualization of the vocal folds. [11] Visualization is considered to be the main method of diagnosis as perceptual evaluation, which includes acoustic and aerodynamic measures, alone is insufficient. [12] Laryngeal videostroboscopy, an imaging technique, is commonly used to view the vocal folds: this procedure can be performed nasally or orally. [11] Vocal fold nodules are most often characterized as bilaterally symmetrical whitish masses, [11] and tend to form at the midpoint of the vocal folds. [12]

Nodules may prevent complete closure of the glottis, also known as glottal closure, and their presence may lead to an hourglass-shaped glottal closure. [11] Voice problems may result from the presence of vocal fold nodules. [13] They are diagnosed based on the presence of perceptual features not explicable by other causes. [13] Such symptoms include: vocal fatigue, breathiness, loss of high pitch notes, lack of vocal control, or increased phonatory effort (i.e. increased effort to produce speech). [13]

Prevention

Regulating voice use

For individuals who work with their voice (e.g., singers, actors, teachers, stock brokers), voice training that includes vocal function exercises (VFEs) may help reduce undue vocal strain. [14] Furthermore, recommendations for voice professionals include warm-up and cool-down exercises for the voice to reduce strain. [14] Additionally, using amplification devices, such as speakers or microphones, is recommended for individuals who speak to large, and even small groups or in the presence of background noise. [6]

Hydration

Staying hydrated decreases the pressure that the vocal folds exert on one another by ensuring sufficient lubrication by mucosa, increasing the efficiency of vocal fold oscillation during speech, and promoting a healthy voice quality. [15] Consumption of caffeine in large quantities is dehydrating and is therefore implicated in an increased risk of vocal fold nodules. [14]

Lifestyle changes

Behaviours such as frequent throat clearing, shouting, speaking over background noise, and hard crying are associated with an increased risk of developing nodules and other vocal pathologies. [14] Furthermore, unconventional voice practices such as speaking in the falsetto register, cause excessive strain and may result in nodules. [16] The avoidance of damaging vocal behaviours may prevent the formation of nodules. Tobacco, alcohol, certain medications, and recreational drugs have also been implicated in pathologies of the vocal folds. [14] Reducing exposure to these substances has been shown to reduce one's risk of nodules. Other behaviours that are implicated in vocal fold nodules include poor sleeping habits and poor nutrition. [14]

Treatment

The two main methods of treating vocal fold nodules are voice therapy (a behavioural treatment) and laryngeal microsurgery (a surgical treatment). [17] Because of general risks of surgery (e.g. scar formation, or those posed by general anesthesia [17] ), behavioural treatment is usually recommended first. [17]

Behavioural treatment

Behavioural voice therapy is typically carried out by speech–language pathologists. [18] While behavioural treatments methods vary greatly, they are generally effective at improving vocal quality and decreasing size of vocal fold nodules. [17] [6] Complete resolution of nodules through behavioural treatment is possible [17] but unlikely. [6]

Behavioural techniques can be indirect or direct. [17] Indirect approaches focus on improving vocal hygiene, introducing and/or maintaining safe voice practices (thereby reducing opportunities for phonotrauma) and, occasionally, implementing vocal rest. [5] Direct approaches involve reducing the physiological strain on the vocal system while the voice is being used (e.g. during speaking or singing), such as by reducing collision forces between the vocal folds, ensuring sufficient pulmonary support while speaking (e.g. by changing the individual's breathing pattern), and optimizing resonance of the larynx and other structures of the vocal apparatus. [6]

Behavioural treatments also vary in delivery model. [17] Traditional therapy distribution (e.g. eight sessions within eight weeks), more intensive approaches (e.g. eight session within three weeks) and remote therapy (i.e. telehealth) have all shown effectiveness in treating vocal fold nodules. [17]

Assessment of outcomes of behavioural treatments also varies greatly. [17] Effects can be measured visually [17] (e.g. by the same methods typically used to confirm the presence of vocal fold nodules: video endoscopy and video stroboscopy [17] ), aerodynamically [17] (e.g. by measuring parameters such as transglottal pressure and the glottal airflow waveform [19] ), perceptually [17] (e.g. by rating the voice in terms of dimensions such as roughness, breathiness, asthenia and strain [17] ), in terms of effect on quality of life measures, [17] or using any combination of the above. [17]

Finally, recurrence of vocal fold nodules after behavioural treatment is always a possibility, particularly if nodules were not completely resolved or if skills gained during treatment were not carried-over outside of therapy sessions or maintained after therapy blocks. [17]

Surgery

When behavioural treatments have been deemed ineffective for a voice user, surgical intervention is often considered. [17] Surgical treatments are considered in cases of unresolved dysphonia which negatively impacts the patient's quality of life. [7] Removal of vocal fold nodules is a relatively safe and minor surgery[ citation needed ]. However, those who sing professionally or otherwise should take serious consideration before having surgery as it can affect the ability to sustain phonation, as well as alter the vocal range. [20] While the patient is subdued under general anesthesia, long thin scissors and scalpels or CO2 surgical lasers might be used to remove the nodules. [20] Microsutures are sometimes used to close the incision. [20] Vocal rest for a period of 4 to 14 days is recommended post surgery to facilitate healing. [2]

Prognosis

Vocal fold nodules typically respond well to non-surgical/behavioural treatment techniques such as those described in the "Treatment" section. Therefore, if the patient is able to engage in such behaviour modification techniques the prognosis is good (although exact data is not available). [1] If lesions are still present after non-surgical treatment methods, it is likely they are another form of benign vocal fold lesion (polyp, fibrous mass, cyst, or pseudocyst). The prognosis of requiring surgery would only occur after an exhaustive attempt at non-surgical therapy techniques has been applied. [7]

Epidemiology

Research on the epidemiology of vocal fold nodules in children has suggested that nodules are more common in boys (2:1), in particular boys who are active and scream more frequently. [10] [21] However, in adulthood, women are more likely to have nodules, and are especially likely if they have an outgoing personality or sing frequently. [14] The exact prevalence of vocal fold nodules is not known, but it has been reported that 23.4% of children who attended an ENT clinic for voice hoarseness, 6% of phoniatric clinic attendees, and 43% of teachers with dysphonia had nodules. [1]

Related Research Articles

The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, and use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition.

Vocal loading is the stress inflicted on the speech organs when speaking for long periods.

<span class="mw-page-title-main">Human voice</span> Sound made by a human being using the vocal tract

The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production in which the vocal folds are the primary sound source.

Vocal fold cysts are benign masses of the membranous vocal folds. These cysts are enclosed, sac-like structures that are typically of a yellow or white colour. They occur unilaterally on the midpoint of the medial edge of the vocal folds. They can also form on the upper/superior, surface of the vocal folds. There are two types of vocal fold cysts:

  1. Sub-epithelial vocal fold cysts- located in the superficial lamina propria of the vocal folds.
  2. Ligament vocal fold cysts- located within the deeper layers of the lamina propria or on the vocal ligament.
<span class="mw-page-title-main">Reinke's edema</span> Medical condition

Reinke's edema is the swelling of the vocal cords due to fluid (edema) collected within the Reinke's space. First identified by the German anatomist Friedrich B. Reinke in 1895, the Reinke's space is a gelatinous layer of the vocal cord located underneath the outer cells of the vocal cord. When a person speaks, the Reinke's space vibrates to allow for sound to be produced (phonation). The Reinke's space is sometimes referred to as the superficial lamina propria.

<span class="mw-page-title-main">Laryngitis</span> Medical condition

Laryngitis is inflammation of the larynx. Symptoms often include a hoarse voice and may include fever, cough, pain in the front of the neck, and trouble swallowing. Typically, these last under two weeks.

<span class="mw-page-title-main">Laryngectomy</span> Surgical procedure

Laryngectomy is the removal of the larynx and separation of the airway from the mouth, nose and esophagus. In a total laryngectomy, the entire larynx is removed. In a partial laryngectomy, only a portion of the larynx is removed. Following the procedure, the person breathes through an opening in the neck known as a stoma. This procedure is usually performed by an ENT surgeon in cases of laryngeal cancer. Many cases of laryngeal cancer are treated with more conservative methods. A laryngectomy is performed when these treatments fail to conserve the larynx or when the cancer has progressed such that normal functioning would be prevented. Laryngectomies are also performed on individuals with other types of head and neck cancer. Post-laryngectomy rehabilitation includes voice restoration, oral feeding and more recently, smell and taste rehabilitation. An individual's quality of life can be affected post-surgery.

<span class="mw-page-title-main">Laryngeal papillomatosis</span> Medical condition

Laryngeal papillomatosis, also known as recurrent respiratory papillomatosis (RRP) or glottal papillomatosis, is a rare medical condition in which benign tumors (papilloma) form along the aerodigestive tract. There are two variants based on the age of onset: juvenile and adult laryngeal papillomatosis. The tumors are caused by human papillomavirus (HPV) infection of the throat. The tumors may lead to narrowing of the airway, which may cause vocal changes or airway obstruction. Laryngeal papillomatosis is initially diagnosed through indirect laryngoscopy upon observation of growths on the larynx and can be confirmed through a biopsy. Treatment for laryngeal papillomatosis aims to remove the papillomas and limit their recurrence. Due to the recurrent nature of the virus, repeated treatments usually are needed. Laryngeal papillomatosis is primarily treated surgically, though supplemental nonsurgical and/or medical treatments may be considered in some cases. The evolution of laryngeal papillomatosis is highly variable. Though total recovery may be observed, it is often persistent despite treatment. The number of new cases of laryngeal papillomatosis cases is approximately 4.3 cases per 100,000 children and 1.8 cases per 100,000 adults annually.

<span class="mw-page-title-main">Bogart–Bacall syndrome</span>

Bogart–Bacall syndrome (BBS) is a voice disorder that is caused by abuse or overuse of the vocal cords.

A hoarse voice, also known as dysphonia or hoarseness, is when the voice involuntarily sounds breathy, raspy, or strained, or is softer in volume or lower in pitch. A hoarse voice can be associated with a feeling of unease or scratchiness in the throat. Hoarseness is often a symptom of problems in the vocal folds of the larynx. It may be caused by laryngitis, which in turn may be caused by an upper respiratory infection, a cold, or allergies. Cheering at sporting events, speaking loudly in noisy situations, talking for too long without resting one's voice, singing loudly, or speaking with a voice that's too high or too low can also cause temporary hoarseness. A number of other causes for losing one's voice exist, and treatment is generally by resting the voice and treating the underlying cause. If the cause is misuse or overuse of the voice, drinking plenty of water may alleviate the problems.

<span class="mw-page-title-main">Contact granuloma</span> Medical condition

Contact granuloma is a condition that develops due to persistent tissue irritation in the posterior larynx. Benign granulomas, not to be confused with other types of granulomas, occur on the vocal process of the vocal folds, where the vocal ligament attaches. Signs and symptoms may include hoarseness of the voice, or a sensation of having a lump in the throat, but contact granulomas may also be without symptoms. There are two common causes associated with contact granulomas; the first common cause is sustained periods of increased pressure on the vocal folds, and is commonly seen in people who use their voice excessively, such as singers. Treatment typically includes voice therapy and changes to lifestyle factors. The second common cause of granulomas is gastroesophageal reflux and is controlled primarily through the use of anti-reflux medication. Other associated causes are discussed below.

Vocal cord paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerves (RLNs), which control all intrinsic muscles of the larynx except for the cricothyroid muscle. The RLN is important for speaking, breathing and swallowing.

Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. The person's voice may also sound strained or they may be nearly unable to speak. Onset is often gradual and the condition is lifelong.

Puberphonia is a functional voice disorder that is characterized by the habitual use of a high-pitched voice after puberty, hence why many refer to the disorder as resulting in a 'falsetto' voice. The voice may also be heard as breathy, rough, and lacking in power. The onset of puberphonia usually occurs in adolescence, between the ages of 11 and 15 years, at the same time as changes related to puberty are occurring. This disorder usually occurs in the absence of other communication disorders.

<span class="mw-page-title-main">Laryngopharyngeal reflux</span> Medical condition

Laryngopharyngeal reflux (LPR) is the retrograde flow of gastric contents into the larynx, oropharynx and/or the nasopharynx. LPR causes respiratory symptoms such as cough and wheezing and is often associated with head and neck complaints such as dysphonia, globus pharyngis, and dysphagia. LPR may play a role in other diseases, such as sinusitis, otitis media, and rhinitis, and can be a comorbidity of asthma. While LPR is commonly used interchangeably with gastroesophageal reflux disease (GERD), it presents with a different pathophysiology.

<span class="mw-page-title-main">Voice therapy</span> Used to aid voice disorders or altering quality of voice

Voice therapy consists of techniques and procedures that target vocal parameters, such as vocal fold closure, pitch, volume, and quality. This therapy is provided by speech-language pathologists and is primarily used to aid in the management of voice disorders, or for altering the overall quality of voice, as in the case of transgender voice therapy. Vocal pedagogy is a related field to alter voice for the purpose of singing. Voice therapy may also serve to teach preventive measures such as vocal hygiene and other safe speaking or singing practices.

Laryngeal cysts are cysts involving the larynx or more frequently supraglottic locations, such as epiglottis and vallecula. Usually they do not extend to the thyroid cartilage. They may be present congenitally or may develop eventually due to degenerative cause. They often interfere with phonation.

Thyroplasty is a phonosurgical technique designed to improve the voice by altering the thyroid cartilage of the larynx, which houses the vocal cords in order to change the position or the length of the vocal cords.

Arytenoid adduction is a surgical procedure used to treat vocal cord paralysis. A suture is used to emulate the action of the lateral cricoarytenoid muscle and position the paralyzed vocal cord closer to the midline. This allows the two vocal cords to meet and can improve speaking and swallowing ability for affected patients. Arytenoid adduction is often performed in conjunction with medialization thyroplasty.

Muscle tension dysphonia (MTD) was originally coined in 1983 by Morrison and describes a dysphonia caused by increased muscle tension of the muscles surrounding the voice box: the laryngeal and paralaryngeal muscles. MTD is a unifying diagnosis for a previously poorly categorized disease process. It allows for the diagnosis of dysphonia caused by many different etiologies and can be confirmed by history, physical exam, laryngoscopy and videostroboscopy, a technique that allows for the direct visualization of the larynx, vocal cords, and vocal cord motion.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Verdolini, Katherine; Rosen, Clark A.; Branski, Ryan C., eds. (2014). "Vocal Fold Nodules (Nodes, Singer's Nodes, Screamer's Nodes". Classification Manual for Voice Disorders-I. Psychology Press. pp. 37–40. ISBN   978-1-135-60020-4.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 Johns, Michael M. (2003). "Update on the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts". Current Opinion in Otolaryngology & Head and Neck Surgery. 11 (6): 456–61. doi:10.1097/00020840-200312000-00009. PMID   14631179. S2CID   45661781.
  3. ↑ Pedersen, Mette; McGlashan, Julian; Pedersen, Mette (2012). "Surgical versus non-surgical interventions for vocal cord nodules". The Cochrane Database of Systematic Reviews (6): CD001934. doi:10.1002/14651858.CD001934.pub2. PMC   7064879 . PMID   22696326.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Colton, Raymond H.; Casper, Janina K.; Leonard, Rebecca (2006). "Nodules". Understanding Voice Problems: A Physiological Perspective for Diagnosis and Treatment. Lippincott Williams & Wilkins. pp. 100–4. ISBN   978-0-7817-4239-9.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Kunduk, Melda; McWhorter, Andrew J (2009). "True vocal fold nodules: the role of differential diagnosis". Current Opinion in Otolaryngology & Head and Neck Surgery. 17 (6): 449–52. doi:10.1097/MOO.0b013e3283328b6d. PMID   19779347. S2CID   8834120.
  6. 1 2 3 4 5 6 Leonard, Rebecca (2009). "Voice therapy and vocal nodules in adults". Current Opinion in Otolaryngology & Head and Neck Surgery. 17 (6): 453–7. doi:10.1097/MOO.0b013e3283317fd2. PMID   19741535. S2CID   42269683.
  7. 1 2 3 Simpson, Blake; Rosen, Clark (2008). "Vocal Fold Nodules". Operative Techniques in Laryngology. Springer. pp. 105–7. doi:10.1007/978-3-540-68107-6_16. ISBN   978-3-540-25806-3. S2CID   234161002.
  8. ↑ Béquignon, Emilie; Bach, Christine; Fugain, Claude; Guilleré, Lia; Blumen, Marc; Chabolle, Frédéric; Wagner, Isabelle (2013). "Long-term results of surgical treatment of vocal fold nodules". The Laryngoscope. 123 (8): 1926–30. doi:10.1002/lary.23768. PMID   23757348. S2CID   36758075.
  9. ↑ Nakagawa, Hideki; Miyamoto, Makoto; Kusuyama, Toshiyuki; Mori, Yuko; Fukuda, Hiroyuki (2012). "Resolution of Vocal Fold Polyps With Conservative Treatment". Journal of Voice. 26 (3): e107–10. doi:10.1016/j.jvoice.2011.07.005. PMID   22082864.
  10. 1 2 Dobres, Rachel; Lee, Linda; Stemple, Joseph C.; Kummer, Ann W.; Kretschmer, Laura W. (1990). "Description of Laryngeal Pathologies in Children Evaluated by Otolaryngologists". Journal of Speech and Hearing Disorders. 55 (3): 526–32. doi:10.1044/jshd.5503.526. PMID   2199731.
  11. 1 2 3 4 Johns, M. M. (January 01, 2003). Update on the etiology, diagnosis, and treatment of vocal fold nodules, polyps, and cysts. Current Opinion in Otolaryngology & Head and Neck Surgery, 11, 6, 456-61.
  12. 1 2 Pedersen M, McGlashan J. Surgical versus non-surgical interventions for vocal cord nodules. Cochrane Database of Systematic Reviews 2012, Issue 6. Art. No.: CD001934. DOI: 10.1002/14651858.CD001934.pub2
  13. 1 2 3 Verdolini, K., Rosen, C.A., & Branski, R.C. (2014). Classification Manual for Voice Disorders-I. New York, New York: Psychology Press.
  14. 1 2 3 4 5 6 7 Behlau, Mara; Oliveira, Gisele (2009). "Vocal hygiene for the voice professional". Current Opinion in Otolaryngology & Head and Neck Surgery. 17 (3): 149–54. doi:10.1097/MOO.0b013e32832af105. PMID   19342952. S2CID   38511217.
  15. ↑ Leydon, Ciara; Sivasankar, Mahalakshmi; Falciglia, Danielle Lodewyck; Atkins, Christopher; Fisher, Kimberly V. (2009). "Vocal Fold Surface Hydration: A Review". Journal of Voice. 23 (6): 658–65. doi:10.1016/j.jvoice.2008.03.010. PMC   2810851 . PMID   19111440.
  16. ↑ Cooper, Morton (1973). Modern Techniques of Vocal Rehabilitation . Thomas. ISBN   978-0-398-02451-2.[ page needed ]
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  18. ↑ Fisher, Kimberly V. (1996). "Vocal fold nodules". Current Opinion in Otolaryngology & Head and Neck Surgery. 4 (3): 166–71. doi:10.1097/00020840-199606000-00002. S2CID   72194214.
  19. ↑ Holmberg, Eva B.; Doyle, Patricia; Perkell, Joseph S.; Hammarberg, Britta; Hillman, Robert E. (2003). "Aerodynamic and acoustic voice measurements of patients with vocal nodules: variation in baseline and changes across voice therapy". Journal of Voice. 17 (3): 269–282. doi:10.1067/s0892-1997(03)00076-6. ISSN   0892-1997. PMID   14513951.
  20. 1 2 3 Benninger, Michael S.; Alessi, David; Archer, Sanford; Bastian, Robert; Ford, Charles; Koufman, James; Sataloff, Robert T.; Spiegel, Joseph R.; Woo, Peak (1996). "Vocal fold scarring: Current concepts and management". Otolaryngology–Head and Neck Surgery. 115 (5): 474–82. doi:10.1016/S0194-5998(96)70087-6. PMID   8903451.
  21. ↑ Prater, Rex J.; Swift, Roger W. (1984). Manual of Voice Therapy. Austin: Pro-Ed. ISBN   978-0-89079-279-7.[ page needed ]
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