Botulinum toxin injection for laryngeal dystonias in singers.
Botulinum toxin injections have been used since the 1980s to treat a number of medical conditions caused by abnormal or unwanted muscular activity. (1) Botulinum toxin is a protein produced by the bacterium, Clostridium botulinum. It binds to nerve endings, thus preventing their normal signaling to muscles and inducing a partial paralysis (paresis). In high doses, this toxin is lethal; however in much smaller, therapeutic doses, botulinum toxin has improved modern medicine, allowing for the relief of symptoms in several medical conditions. Singing teachers should be familiar with this therapeutic modality and its effects on voice.
In the U. S., botulinum toxin is available primarily as Botox, or onobotulinum toxin A (Allergan, Irvine), Dysport, or abobotulinum toxin A (Galderma, Switzerland), Xeomin, or incobotulinum toxin A (Merz, Germany), and Myobloc, or rimabotulinum toxin B (Solstice Neurosciences, San Francisco). Botox, Dysport, and Xeomin must be reconstituted allowing for control over the final concentration while Myobloc comes in concentrations of 500 mouse units/0.1ml. Botox is the most commonly used formulation of botulinum toxin for laryngeal dystonias in the U. S. It is important to appreciate that dosing for each product is not interchangeable. For example, Botox is 2.5-4 times more potent than Dysport; in other words, Dysport doses are often 2.5-4 times those of Botox to achieve a similar clinical effect. (2) For the treatment of spasmodic dysphonia, Botox was found to be 52. (3) times more potent than Myobloc in a comparison study. (3) Compared to Botox, Myobloc has been shown to have a faster onset of action, a shorter duration of effect, and a larger radius of diffusion. (4) The dosing described in this article will be based on Botox preparation unless otherwise specified.
Botulinum toxin might be of particular interest to singers because it has been used to treat a number of voice disorders. This article describes the clinical uses of botulinum toxin to manage spasmodic dysphonia, singer's dystonia, essential vocal tremor, unilateral and bilateral laryngeal synkinesis, paradoxical vocal fold motion, and occupational oromandibular dystonia. It should be remembered that a comprehensive neurolaryngologic workup is recommended to evaluate for other possible causes of the patient's presenting signs and symptoms prior to initiating treatment.
Spasmodic dysphonia (SD) is a laryngeal dystonia that occurs when speaking. A dystonia is a condition characterized by abnormal muscle movement and tone. Spasmodic dysphonia is most common in middle-aged women, and typically symptoms develop gradually. (5) Initially, symptoms are not usually observed during singing, laughing, crying, or speaking in an atypical manner, such as high-pitched voice used to talk with children or animals. However, advanced SD affects all forms of phonation. There are two main types of SD. The adductor type (AdSD) pulls the vocal folds together causing voice breaks in words and a strained or strangled voice quality. Patients with AdSD may try to compensate by whispering. The abductor type (AbSD) pulls the vocal folds apart causing breathy breaks in the voice, or a whispered voice quality. (6)
Adductor spasmodic dysphonia is far more common than the abductor type (10:1); (7)but rarely, patients may have both simultaneously (mixed laryngeal dystonia). The disorder must be differentiated from hyperfunctional and psychogenic dysphonias, as well as essential vocal tremor (EVT), or other vocal tremor, which can be present in up to 25% of patients with AdSD. (8) In most patients with SD, only the intrinsic muscles of the larynx are affected. However, some patients also have involuntary muscle contractions in other parts of the body, such as the eyelids. (9) The cause of SD is unknown, but it may be associated with a number of genetic and environmental factors, including history of intense voice use, tremor, blepharospasm (involuntary contraction of the eyelid), and family history of voice disorders. (10) Voice therapy alone often yields unsatisfactory results in these patients, although voice therapy may reduce or eliminate compensatory hyperfunction. This in turn allows the underlying dystonia to be assessed more accurately in many cases. Botulinum toxin injections can temporarily eliminate the spasmodic quality from the voice in most patients. In addition to botulinum toxin, some people with SD benefit from oral medications that act on the central nervous system, such as propranolol, primidone, baclofen, and some anticonvulsants like phenytoin, particularly if the patients have other forms of dystonia. (11) Conversely, denervation surgery can provide a permanent solution for patients with AdSD (12) and for some patients with AbSD. (13) These treatment modalities are discussed below in more detail.
Singer's dystonia is a rare subtype of laryngeal dystonia that has been recognized in the last 10 years. (14) Singer's dystonia is a technique independent, vocal fatigue independent, task and/or pitch specific dystonia present only when singing. While this condition has been reported only in a small number of singers, timely diagnosis is important for prompt treatment and continuation of a singer's career. Singer's dystonia is very similar to spasmodic dysphonia in that it is task-specific, occurs most often in middle-aged women, and the adductor type is more common than the abductor type. However, unlike SD, singer's dystonia usually occurs only when singing, although it may progress to affect speaking or other parts of the body. (15)
Singer's dystonia may present in a number of ways. While those with singer's dystonia may sing often, their symptoms are not caused by phonotrauma or overuse. (16) Adductor singer's dystonia may cause vocal instability, roughness, loss of vibrato, loss of resonance, poor endurance, vocal strain, vocal fatigue, "flatness," "crackling," raspiness, or voice cutoffs at certain pitches. These symptoms tend to occur during transition from chest or middle to head voice, usually just below the second passaggio, (17) in those singers who have more than one passaggio. Only two cases of abductor singer's dystonia have been reported in the literature. The first patient had breathy spasms on voiceless consonants mostly in the area of the upper passaggio; (18) the second patient had unvoiced breaks and fatigue in the mid-to-upper range with compensatory hyperadduction. (19)
Singer's dystonia is probably underdiagnosed as a result of attributing the symptoms to improper technique, aging, or due to misdiagnosis as essential vocal tremor. Halstead et al. have identified three criteria for the diagnosis of singer's dystonia:
1) Laryngeal electromyography must show increased muscle discharge of the thyroarytenoid or posterior cricoarytenoid muscles at the affected pitch(es).
2) Spectrographic analysis of singing must show widely spaced vertical striations (on adductor tasks) or aphonic breaks (on abductor tasks).
3) Task-specific and/or pitch specific, reproducible vocal instability on ascending and descending scales must be without tension present in other muscles or structures that could affect the voice.
Additionally, a singing voice specialist must rule out the presence of any treatable technical errors, such as register breaks and vibrato issues, before a definitive diagnosis can be made. Finally, a comprehensive neurolaryngologic work-up should be completed to confirm that there are not other neurological causes for the symptoms. (20)
Early diagnosis and treatment are important, because singer's dystonia can incite frustration and lead to singer's guilt. (21) Voice therapy and botulinum toxin injections are used to treat the symptoms. With the help of a singing voice specialist and speech-language pathologist, a singer can learn new techniques to facilitate sustained phrases by minimizing voiceless consonants, decreasing time spent singing at the affected pitch, substituting voiceless consonants for voiced consonants, reducing compensatory mechanisms, or choosing a different repertoire. Nevertheless, many patients are not able to sing at their pre-symptom level, even after voice therapy and botulinum toxin injections. (22) This disorder may result in a career shift from singer to a position with fewer vocal demands such as a singing teacher, songwriter, conductor, or producer.
Essential Vocal Tremor
Essential vocal tremor is present alone (not associated with SD) in 0.3-1% of the population. (23) It is likely to be associated with tremor elsewhere in the body, so there are few studies evaluating prevalence and treatment in isolated cases. Essential tremor is a chronic, progressive, neurological disease with an unknown etiology, and as many as 25% of people with EVT have voice symptoms. (24) Essential tremor should be considered a diagnosis of exclusion after other causes, such as Parkinson disease, have been ruled out through thorough, expert neurological evaluation. (25)
Although EVT represents a risk factor for dystonias like SD, these conditions have different developmental patterns, symptoms, and epidemiology. (26) Unlike SD, EVT presents as a rhythmic alteration in frequency (pitch) and/or amplitude (loudness) without a strained or strangled voice quality. (27) Katherine Hepburn's voice in her older years is a good example of EVT. Additionally, EVT is not task-specific, unlike SD. (28) Even though SD and EVT are more common in females, EVT usually occurs at an older age and is more closely associated with the aging process. (29)
Spasmodic dysphonia usually only has a horizontal component affecting the intrinsic laryngeal muscles, but EVT may have both horizontal and vertical components involving the intrinsic and extrinsic ("strap") muscles of the larynx. For predominantly horizontal EVT, botulinum toxin can be injected into both thyroarytenoid muscles. For predominately vertical EVT, botulinum toxin is injected into each strap muscle to relieve symptoms. If both components are present, injections may be alternated over weeks or months to minimize side effects. (30)
The thyroarytenoid (TA) is usually the most involved muscle in a vocal tremor, but people with concurrent AdSD and EVT respond less optimally to TA botulinum toxin injections than those with isolated AdSD. Since all intrinsic laryngeal muscles could be involved in EVT, many patients with concurrent AdSD and EVT prefer injections into both TA and other muscles for increased benefit. Unfortunately, injection of multiple muscles for severe isolated EVT increases the risk for adverse effects including dysphagia, because higher doses are required. (31) The likelihood of response to oral medications such as propranolol, primidone, and some anticonvulsants is higher than SD. The success of medical treatment for SD alone is extremely low.
Unilateral and Bilateral Laryngeal Synkinesis
Unilateral or bilateral laryngeal synkinesis would probably end any professional singing career, but it is worthy of discussion for completeness of this topic. Synkinesis is inappropriate muscle activation caused by nerves routed to the wrong muscle. For example, a nerve that should go to a muscle that closes the vocal fold gets rerouted totally or partially to a muscle that opens the vocal fold. So, when the brain activates that nerve, to bring the vocal folds together, the muscles that pull them apart also are engaged in the process. Laryngeal synkinesis occurs when the recurrent laryngeal nerve is injured, usually after trauma or surgery, and then nonselectively reinnervates both adductor and abductor muscles. (32) Immediately after injury to the nerve, the voice may be breathy, and in some cases, aspiration or airway obstruction may occur. Within three to nine months, reinnervation synkinesis may develop that can result in upper airway obstruction and difficulty breathing if both recurrent nerves have been injured, depending on the proportion of adductor and abductor fibers reinnervated. (33) The most effective treatment for this complication is a tracheotomy, which may be aesthetically undesirable for some patients. (34) Alternately, endoscopic surgical alterations of the larynx can be performed to improve the airway, but most of these procedures improve breathing at the expense of voice quality. (35)
More recently, botulinum toxin injections to the adductor muscles have been shown to be effective in reducing upper airway obstruction in some patients by permitting unopposed action of the laryngeal abductor muscle (posterior cricoarytenoid). (36) While some cases of unilateral vocal fold paralysis and synkinesis have been successfully treated with botulinum toxin, it has been more successful in the management of bilateral paralysis. Once the diagnosis of bilateral laryngeal synkinesis has been confirmed via laryngeal electromyography (LEMG), injections can be placed unilaterally or bilaterally. The best candidates for this treatment are those who do not require urgent relief of airway obstruction, those who have had repeated emergency department visits, those without cricoarytenoid joint fixation, and tracheotomy dependent patients. (37) Simlarly, botulinum toxin injections can facilitate capping trials of the tracheotomy tube and increase the probability of decannulation (removal of the tracheotomy tube). (38)
Paradoxical Vocal Fold Motion
Paradoxical vocal fold motion (PVFM) is a disorder in which the laryngeal muscles adduct (close) during inspiration, when they should abduct (open). An affected patient may present with episodes of shortness of breath, hoarseness, wheezing, stridor (loud inspiratory breathing noise), cough, voice loss, and/or throat tightness. (39) This disorder occurs most often in middleaged females and in young athletes. It may be due to a psychological disorder in some patients, but it is more commonly due to respiratory dystonia (a neurological movement disorder like SD), and it often is aggravated by exercise and/or specific irritants. Gastroesophageal reflux and asthma sometimes cause laryngospasm that can be confused with PVFM. (40) PVFM is best diagnosed with laryngoscopy during an attack, but patient questionnaires and diagnostic tests are helpful to eliminate other potential etiologies. Testing may include pulmonary function tests, laryngeal EMG, and 24-hour pH impedence testing with symptom index, among others. Prompt diagnosis and early intervention with voice therapy are useful in preventing frequent emergency room visits and unnecessary intubation and tracheotomy. While speech therapy is helpful in many patients, botulinum toxin injection of the TA muscle(s) is the most effective treatment for respiratory dystonia and in recent years has become a mainstay of treatment. (41) There is also a related condition called cough variant dystonia that causes intractable coughing and responds to botulinum toxin.
Occupational Oromandibular Dystonia
While dysphonia resulting from a focal dystonia is usually laryngeal in origin, voice teachers and singers need to be aware of other focal dystonias that may affect singing. Occupational oromandibular dystonia usually affects musicians who play wind instruments. Recently, this disorder was reported in an opera singer who had an 8-year history of mandibular tremors and inability to sing high notes. With time, the tremor progressed, and the singer's mouth closed completely when singing high notes. This performer was forced to end her career as an opera singer, but with botulinum toxin injections into both masseter (jaw) muscles, she was able to pursue a career as a voice teacher. (42)
The gold standard therapy for most laryngeal dystonias is botulinum toxin injections, but the dosage, frequency, approach, side effect profile, and results vary for each type of dystonia and for each individual. For AdSD, the initial dose is usually 1-5 mouse units (MU) injected into each thyroarytenoid (TA) muscle. Approximately three to nine months later when the effects begin to wear off, the patient is reassessed, and the dose is adjusted based on severity of side effects and duration of best voice. It sometimes takes 3 to 4 injections until the ideal dose is achieved. (43) Bilateral injections of 0.6-2.5 MU per vocal fold are typical for AdSD, (44) although doses of 5 MU are common, and 10 MU on each side is not rare. Essential vocal tremor is treated the same way but with lower doses and injection of other muscles. Occasionally, the extralaryngeal muscles and the cricothyroid muscles are injected to improve the tremor. In AbSD, one posterior cricoarytenoid (PCA) muscle is injected with 3.75-5 MU. In about 2 weeks, the voice quality and unwanted side effects are assessed to determine the proper dose for the opposite PCA muscle. (45) The senior author (RTS) routinely uses 15 MU per PCA, alternating every 3 months, provided the injections are well tolerated. (47) Simultaneous, bilateral low dose injections can be used in some cases. In some patients with AbSd, it is also necessary to inject the CT muscles. In singer's dystonia, the average dose in each TA muscle is 0.25 MU, which is much lower than for AdSD. (48)
Severity of dystonia, age, and gender have not been shown to correlate with the dose of botulinum toxin required for optimum effect. However, those with AdSD and EVT who are in good health and have an ideal body mass index (BMI) may need a higher dose for maximum effect. (49) While age does not correlate well with dose, people over the age of 70 generally experience less improvement in their voices than younger patients after botulinum toxin injection. (50) Over time, dose adjustments may be necessary to maintain maximal effect while keeping side effects to a minimum. (51)
Side effects of botulinum toxin injections into the laryngeal muscles are expected, but the goal is to find a dose that minimizes their severity and duration. Despite attempts at standardization, the dosage and frequency of botulinum toxin injections remain specific to the individual and should be determined on a case-by-case basis. In general, AdSD responds better to botulinum toxin injections than AbSD. (52) In about 30% of botulinum toxin injections, patients showed a decline in vocal function for 1-2 weeks followed by improvement until reaching a plateau. On average, a person remains at the plateau level for 40% of the entire 3-4 month injection cycle, but remains above baseline function for more than 90% of the cycle. (53) With higher doses, both the desirable and undesirable effects last longer. In AdSD, undesirable effects include breathy voice, difficulty swallowing, and shortness of breath while speaking. The average duration of these symptoms was found to be 2-3 weeks for breathiness, 1-2 weeks for difficulty swallowing, and 12 days for shortness of breath while speaking in one study. (54) With AbSD, transient wheezing, stridor, shortness of breath, or difficulty swallowing may occur following injection. These symptoms occur rarely when only one side is injected per visit. (55)
Additionally, botulinum toxin injections into the larynx result in decreased volume, projection, vibrato, and ability to hit high notes. (56) With these undesirable effects, it is easy to appreciate the importance of proper dosing in singers. To minimize these problems, unilateral or staggered injections (every two weeks or longer) can be done. Another strategy is to administer very low doses bilaterally at more frequent intervals. (57) A patient with singer's dystonia was given botulinum toxin injections in her false vocal folds, which avoided the side effects, allowing her to continue singing in a local theater. (58) This may prove successful in others with singer's dystonia; however, successful injection results in at least some paresis (weakness) of the thyroarytenoid muscle which constitutes the body of the vocal fold. Paresis weakens lateral resistance, so the voice is likely to "break up" during loud phonation, and this can be a substantial problem for singers even when more speech has been restored.
There are contraindications to using botulinum toxin. Botulinum toxin should not be used in patients who are pregnant, breastfeeding, taking aminoglycoside antibiotics, have an underlying systemic neuromuscular disease (i.e., myasthenia gravis), have a known botulinum toxin sensitivity, (59) or in patients for whom it does not work (such as those who have developed antibodies to botulinum toxin). When patients develop antibodies to botulinum toxin type A, they can be treated with botulinum toxin type B, or with surgery. (60)
One of the most problematic downsides to botulinum toxin injections is that they are temporary. A more permanent alternative treatment for AdSD is selective laryngeal adductor denervation (SLAD) or denervation-reinnervation (SLAD-R) surgery. People seek this alternative treatment for many reasons: they want a definitive cure, the injections stopped working, the injections are costly (not always covered by insurance), the injections result in undesirable side effects, and traveling for the injections is difficult. (61) During this procedure, the branches of the recurrent laryngeal nerve innervating the thyroarytenoid (TA) and lateral cricoarytenoid (LCA) muscles are transected. To prevent regrowth and aberrant reinnervation of the muscles, the end of the nerve is joined to the ansa cervicalis. Denervating the LCA improves success, but increases the duration of breathiness. (62) We have found that nerve section combined with adequate myomectomy works well without adding reinnervation; this is the technique introduced by Iwamura. (63) Although performed less frequently, an abductor (PCA) denervation procedure has been described for AbSD based on anatomic studies of the recurrent laryngeal nerve and its branches by the senior author (RTS) and his colleagues. (64)
Following surgery, patients usually are breathy for 3-6 months, and breathiness may be permanent. (65) After surgery, some still experience adductor voice breaks, but many enjoy long term improvement and would recommend the surgery to others. Similarly, most patients (83% in one large study) would recommend surgery over botulinum toxin injections. Postsurgery recurrence of symptoms has been reported in about 10% of cases, with symptoms arising within 12 months of the surgery. Additionally, moderate-to-severe breathiness may persist in up to 20% of cases, warranting a discussion with the patient prior to surgery. (66) The most recent literature has concluded that SLAD-R surgery is equal to, if not better than, botulinum toxin in improving the symptoms of AdSD, (67) and we have seen similar results with SLAD without reinnervation but with partial muscle resection. The risks and benefits should be evaluated when determining the best treatment for each patient. For singers, the recovery time after surgery and the risk of permanent breathiness should be taken into account, as well as the results of an adequate trial of botulinum toxin injections (if not contraindicated).
There are a number of laryngeal dystonias for which botulinum toxin is an effective therapy; however, the lack of permanence remains the biggest drawback. Voice therapy and oral medications may be used in conjunction with botulinum toxin injections, but they are often inadequate when used alone for the conditions discussed in this article. Selective denervation surgery is an alternative option replacing regular botulinum toxin injections for severe cases of AdSD and AbSD. Particularly in the singer, botulinum toxin injections should be pursued first before giving any serious thought to surgery. As our understanding of laryngeal dystonias improves, more clearly defined diagnoses will emerge like the recently described singer's dystonia, and novel treatments will be developed to safely ameliorate the symptoms. Educating singers and voice professionals about these disorders will improve awareness leading to timely diagnosis, and with proper treatment, allow singers to continue successful careers in music.
(1.) Julina Ongkasuwan and Mark Courey, "The Role of Botulinum Toxin in the Management of Airway Compromise Due to Bilateral Vocal Fold Paralysis" Current Opinion in Otolaryngology & Head and Neck Surgery 19, no. 6 (December 2011): 444-448; doi:10.1097/MOO.0b013e32834c1e4f.
(2.) Raymond L. Rosales, Hans Bigalke, and D. Dressler, "Pharmacology of Botulinum Toxin: Differences Between Type A Preparations, " European Journal of Neurology 13, no. S1 (February 2006): 2-10; doi:10.1111/j.1468-1331.2006. 01438.x.
(3.) Andrew Blitzer, "Botulinum Toxin A and B: A Comparative Dosing Study for Spasmodic Dysphonia," Otolaryngology-Head and Neck Surgery 133, no. 6 (December 2005): 836-838; doi:10.1016/j.otohns.2005.09.008.
(4.) Ibid.; Timothy Corcoran Flynn and Robert E. Clark II, "Botulinum Toxin Type B (Myobloc) Versus Botulinum Toxin Type A (Botox) Frontalis Study: Rate of Onset and Radius of Diffusion," Dermatologic Surgery 29, no. 5 (May 2003): 519-522; doi:10.1046/j.1524-4725.2003.29124.x.
(5.) Robert T. Sataloff, Mona Abaza , and Mary Hawkshaw, "Spasmodic Dysphonia," Journal of Singing 55, no. 4 (March/April 1999): 49-51; http://search.proquest.com/docview/1402205?accountid=10559.
(6.) Andrew Blitzer, "Spasmodic Dysphonia and Botulinum Toxin: Experience from the Largest Treatment Series," European Journal of Neurology 17, no. S1 (July 2010): 28-30; doi: 10.1111/j.1468-1331.2010.03047.x.
(7.) Andrew Blitzer and Mitchell F. Brin, "Laryngeal Dystonia: A Series with Botulinum Toxin Therapy," The Annals of Otology, Rhinology & Laryngology 100, no. 2 (February 1991): 85-89; doi:10.1177/000348949110000201.
(8.) Sataloff, Abaza, and Hawkshaw; Kristine Tanner et al., "Risk and Protective Factors for Spasmodic Dysphonia: A Case-Control Investigation," Journal of Voice 25, no. 1 (January 2011): e35-46; doi:10.1016/j.jvoice.2009.09.004.
(9.) Blitzer, "Spasmodic Dysphonia."
(10.) Tanner et al.
(11.) Lowell E. Gurey, Catherine F. Sinclair, and Andrew Blitzer, "A New Paradigm for the Management of Essential Vocal Tremor with Botulinum Toxin, " The Laryngoscope 123, no. 10 (October 2013): 2497-2501; doi:10.1002/lary.24073.
(12.) Sataloff, Abaza, and Hawkshaw; Blitzer, "Spasmodic Dysphonia."
(13.) Robert T. Sataloff et al., Surgical Techniques in Otolaryngology--Head and Neck Surgery: Laryngeal Surgery (New Delhi: Jaypee Brothers Medical Publishers, 2013).
(14.) Ajay Chitkara et al., "Singer's Dystonia: First Report of a Variant of Spasmodic Dysphonia," The Annals of Otology, Rhinology & Laryngology 115, no. 2 (February 2006): 89-92; http://search.proquest.com/docview/217907415?accountid=10559.
(15.) Ibid.; Lucinda A. Halstead, Deanna M. McBroom, and Heather Shaw Bonilha, "Task-Specific Singing Dystonia: Vocal Instability That Technique Cannot Fix," Journal of Voice 29, no. 1 (January 2015): 71-78; doi:10.1016/j.jvoice. 2014.04.011.
(16.) Halstead, McBroom, and Bonilha.
(17.) Ibid.; Chitkara et al.
(18.) Halstead, McBroom, and Bonilha.
(19.) Chitkara et al.
(20.) Halstead, McBroom, and Bonilha.
(23.) Paul Warrick et al., "The Treatment of Essential Voice Tremor with Botulinum Toxin A: A Longitudinal Case Report," Journal of Voice 14, no. 3 (September 2000): 411; doi:http://dx.doi.org/10.1016/S0892-1997(00)80086-7.
(24.) Gurey, Sinclair, Blitzer.
(25.) Tanner et al.; Warrick et al., 410.
(26.) Tanner et al.
(27.) Diana M. Orbelo et al., "Differences in Botulinum Toxin Dosing Between Patients with Adductor Spasmodic Dysphonia and Essential Voice Tremor," Journal of Voice 28, no. 1 (January 2014): 123-127; doi:10.1016/j.jvoice.2013. 05.008.
(28.) Gurey, Sinclair, and Blitzer.
(29.) Warrick et al., 10-21; Orbelo et al.
(30.) Gurey, Sinclair, and Blitzer.
(31.) Katherine A. Kendall and Rebecca J. Leonard, "Interarytenoid Muscle Botox Injection for Treatment of Adductor Spasmodic Dysphonia with Vocal Tremor," Journal of Voice
25, no. 1 (January 2011): 114-119; doi:10.1016/j.jvoice.2009. 08.003.
(32.) Ongkasuwan and Courey.
(34.) Pedro A. Andrade Filho and Clark A. Rosen, "Bilateral Vocal Fold Paralysis: An Unusual Treatment with Botulinum Toxin," Journal of Voice 18, no. 2 (June 2004): 254-255; doi:http://dx.doi.org/10.1016/j.jvoice.2003.05.002.
(35.) Ongkasuwan and Courey.
(36.) Adam D. Rubin and Robert T. Sataloff, "Vocal Fold Paresis and Paralysis," in Robert T. Sataloff, ed., Professional Voice: The Science and Art of Clinical Care, 3rd edition (San Diego: Plural Publishing, 2005), 871-886.
(37.) Ongkasuwan and Courey; Todd G. Dray, "Botox in the Management of Bilateral Vocal Cord Synkinesis," Operative Techniques in Otolaryngology-Head and Neck Surgery 23, no. 2 (June 2012): 92-95; doi:http://dx.doi.org/10.1016/j.otot.2011.11.003.
(39.) Ken W. Altman et al., "Paradoxical Vocal Fold Motion: Presentation and Treatment Options," Journal of Voice 14, no. 1 (March 2000): 99-103; doi:http://dx.doi.org/10.1016/S0892-1997(00)80099-5.
(40.) Ibid.; Anne E. Vertigan et al.,"The Relationship Between Chronic Cough and Paradoxical Vocal Fold Movement: A Review of the Literature," Journal of Voice 20, no. 3 (September 2006): 466-80; doi:http://dx.doi.org/10.1016/j.jvoice.2005.08.001; Venu Divi, Mary J. Hawkshaw, and Robert T. Sataloff, "Paradoxical Vocal Fold Motion," in Christopher J. Hartnick and Mark E. Bosely, eds., Pediatric Voice Disorders (San Diego: Plural Publishing, Inc., 2008), 253-264.
(41.) Altman et al.
(42.) Hesham Abboud, Ilia Itin, and Hubert Fernandez, "Occupational Oromandibular Dystonia in an Opera Singer Mimicking Spasmodic Dysphonia," Music and Medicine 4, no. 1 (January 2012): 37-39; doi: 10.1177/1943862111429130.
(43.) Daniel Novakovic et al., "Botulinum Toxin Treatment of Adductor Spasmodic Dysphonia: Longitudinal Functional Outcomes," The Laryngoscope 121, no. 3 (March 2011): 606-612; doi:10.1002/lary.21395.
(44.) Manish Shah and Michael M. Johns III, "Office-Based Botulinum Toxin Injections," Otolaryngologic Clinics of North America 46, no. 1 (February 2013): 53-61; doi:10.1016/j.otc.2012.08.017.
(47.) Robert T. Sataloff and Daniel A. Deems, "Spasmodic Dysphonia," in Robert T. Sataloff, ed., Professional Voice: The Science and Art of Clinical Care, 3rd edition (San Diego: Plural Publishing, 2005), 887-907.
(48.) Chitkara et al.
(49.) David L. Young and Lucinda A. Halstead, "Relationship of Laryngeal Botulinum Toxin Dosage to Patient Age, Vitality, and Socioeconomic Issues," Journal of Voice 28, no. 5 (September 2014): 614-617; doi:10.1016/j.jvoice.2013.10.024.
(50.) Michael P. Cannito, Joel C. Kahane, and Lesya Chorna, "Vocal Aging and Adductor Spasmodic Dysphonia: Response to Botulinum Toxin Injection," Clinical Interventions in Aging 3, no. 1 (March 2008): 131-151; doi:http://dx.doi.org/10.2147/CIA.S1416; David E. Rosow et al., "Factors Influencing Botulinum Toxin Dose Instability in Spasmodic Dysphonia Patients," Journal of Voice 29, no. 3 (May 2014); doi:10.1016/j.jvoice.2014.08.011.
(51.) Rosow et al.
(53.) Tanner et al.
(54.) Novakovic et al.
(55.) Blitzer, "Spasmodic Dysphonia."
(58.) Halstead, McBroom, and Bonilha.
(59.) Shah and Johns.
(60.) Robert T. Sataloff et al., "Botulinum Toxin Type B for Treatment of Spasmodic Dysphonia: A Case Report," Journal of Voice 16, no. 3 (September 2002): 422-424; doi:http://dx.doi.org/10.1016/S0892-1997(02)00114-5.
(61.) Dinesh K. Chhetri et al., "Long-Term Follow-Up Results of Selective Laryngeal Adductor Denervation-Reinnervation Surgery for Adductor Spasmodic Dysphonia," The Laryngoscope 116, no. 3 (April 2006): 635-642; doi:10.1097/01.MLG.0000201990.97955.E4.
(62.) Dinesh K. Chhetri and Gerald S. Berke, "Treatment of Adductor Spasmodic Dysphonia with Selective Laryngeal Adductor Denervation and Reinnervation Surgery," Otolaryngologic Clinics of North America 39, no. 1 (February 2006): 101-109; doi:http://dx.doi.org/10.1016/j.otc.2005.10.005.
(63.) Iwamura Shinobu, "Comments on Spasmodic Dysphonia: State of the Art," in Van Lawrence, ed., Transcripts of the Eighth Symposium: Care of the Professional Voice (New York: The Voice Foundation, 1979), 26-32.
(64.) Robert L. Eller et al., "The Innervation of the Posterior Cricoarytenoid Muscle: Exploring Clinical Possibilities," Journal of Voice 23, no. 2 (March 2009): 229-234; doi:http://dx.doi.org/10.1016/j.jvoice.2007.01.007.
(65.) Chhetri and Berke, "Adductor Spasmodic Dysphonia"; Abie H. Mendelsohn and Gerald G. Berke, "Surgery or Botulinum Toxin for Adductor Spasmodic Dysphonia: A Comparative Study," The Annals of Otology, Rhinology & Laryngology 21, no. 4 (April 2012): 231-238; http://search.proquest.com/docview/1002361825?accountid=10559.
(66.) Chhetri et al.
(67.) Ibid.; Chhetri and Berke; Mendelsohn and Berke; Adam S. Deconde et al., "Functional Reinnervation of Vocal Folds After Selective Laryngeal Adductor Denervation-Reinnervation Surgery for Spasmodic Dysphonia," Journal of Voice 26, no. 5 (September 2012): 602-603; doi:10.1016/j.jvoice.2011.10.008.
Kirsten Meenan received her Bachelor of Science from the University of Pittsburgh, where she studied biology, chemistry, and theater arts, and she is currently pursuing her medical degree at Drexel University College of Medicine.
Aaron J. Jaworek, MD completed a fellowship in laryngology and care of the professional voice under the mentorship of Robert T. Sataloff, MD, DMA, FACS at Drexel University College of Medicine and the American Institute of Voice and Ear Research. Dr. Jaworek earned a Bachelor of Arts with honors in Biochemistry at New York University in 2004. He then earned his medical degree at the University of South Florida, College of Medicine in 2009. Residency training in Otolaryngology-Head and Neck Surgery was completed in 2014 at the University of Florida, College of Medicine. He recently returned to the Lehigh Valley in Pennsylvania to join Bethlehem ENT Associates and the Adult and Child ENT Center upon completion of fellowship training in 2015.
Robert T. Sataloff, Associate Editor
Wan February with weeping cheer, Whose cold hand guides the youngling year Down misty roads of mire and rime, Before thy pale and fitful face The shrill wind shifts the clouds apace Through skies the morning scarce may climb. Thine eyes are thick with heavy tears, But lit with hopes that lights the year's. Algernon Charles Swinburne, A Years Carols, "February"
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Care of the Professional Voice|
|Author:||Meenan, Kirsten; Jaworek, Aaron; Sataloff, Robert T.|
|Publication:||Journal of Singing|
|Date:||Jan 1, 2016|
|Previous Article:||One trick pony.|
|Next Article:||Can a singer's personalized formant frequency space be helpful in performing multiple styles?|