Neurological Trauma & Disease Vocal Program

The Voice and Swallowing Institute
New York Eye and Ear Infirmary of Mount Sinai
310 E. 14th Street
New York, NY  10003
TEL: (212) 979-4119

About the Program

At The Voice and Swallowing Institute, neurological disorders that affect the larynx and vocal folds form an area of special focus, both for clinical care and research. These include:

  1. Vocal fold paralysis

  2. Spasmodic dysphonia

  3. Voice disorders associated with Parkinson’s Disease

  4. Vocal tremor

  5. Other disorders of involuntary movement of the larynx, such as tics and myoclonus

The Institute offers expertise in neurolaryngology coupled with the latest techniques, such as laryngeal electromyography (EMG) and videokymography, to aid in the diagnosis of these disorders.  

A complete range of rehabilitative options is available to patient with vocal fold paralysis, from voice therapy to various surgeries. As is the case with other voice disorders, there is no one single solution appropriate for every patient. The correct choice for you depends, first and foremost, on your personal needs. Other important factors are the reason for the condition and length of time the condition has been present. The specialists at The Voice and Swallowing Institute will give you the information you need to make an informed, safe choice.

The Institute offers botulinum toxin therapy for a wide variety of movement disorders of the head & neck, including, of course, spasmodic dysphonia. Botulinum toxin has helped thousands of spasmodic dysphonia sufferers return to happy, productive lives. Speak to the team at the Institute to learn about botulinum toxin and decide if it’s appropriate for you.

Research projects in neurolaryngology are principally concerned with the neural signals controlling laryngeal muscles that arise from the central nervous system and of sensory components of the vocal process, including tracheal and pharyngeal components. Advances in neurophysiology are often accompanied by development of improved diagnostic instruments and methods of clinical treatment.


Vocal Fold Paralysis

Unilateral | Bilateral Vocal Fold Paralysis

Paralysis of one or both vocal folds may happen under a number of circumstances. Since the causes, symptoms and treatment of unilateral vocal fold paralysis are so different from those of bilateral vocal fold paralysis, these will be considered separately. 

The vocal fold on the right side of this picture is paralyzed, so that the vocal folds do not close completely during phonation

VOCAL FOLD PARALYSIS: PHONATION - The vocal fold on the right side of this picture is paralyzed, so that the vocal folds do not close completely during phonation.

Normally, open vocal folds form a symmetric "V" shape. The vocal fold on the right side of this picture is paralyzed, so that it cannot move outward or inward

VOCAL FOLD PARALYSIS: BREATHING - Normally, open vocal folds form a symmetric "V" shape. The vocal fold on the right side of this picture is paralyzed, so that it cannot move outward or inward.


Unilateral Vocal Fold Paralysis

Unilateral vocal fold paralysis is immobility of one vocal fold because of nerve dysfunction. Although there are other reasons for a vocal fold to be immobile, they are uncommon. The recurrent laryngeal nerve is the main nerve that accounts for most of the movement of each vocal fold. It is called “recurrent,” because it travels from the brain into the chest and then back up to the larynx, thus “recurring” in the neck. This nerve can be damaged by various diseases, by certain surgeries, and probably by viral infections. It is important to understand that in the case of surgeries, immobility of the vocal fold does not mean that the nerve was cut. Sometimes even a little bit of handling of the nerve can stop it functioning for a time. The first question to be answered upon diagnosis of vocal fold paralysis is why the nerve is not functioning. 




Carotid endarterectomy

Lung operations, particularly on the left side

Heart operations, especially aortic valve replacement or repair

Repair of thoracic aortic aneurysm

Anterior cervical diskectomy

Mediastinoscopy/mediastinal lymph node biopsy

Closure of patent ductus arteriosus

Brain surgery, especially at the base of the brain or brainstem


Thyroid cancer

Tuberculosis, Sarcoid or anything that causes lymph nodes to enlarge in the chest


Various neurologic diseases, such as Charcot-Marie-Tooth, Shy-Drager, and Multisystem atrophy

Normally the vocal folds are able to open and close symmetrically. With these two motions, they accomplish three tasks: open to allow breathing, close to prevent food from entering the trachea (windpipe) when one swallows, and close to produce voice with air from the lungs.

When one vocal fold is paralyzed, the larynx is unable to completely close. Thus breathing is usually normal, since it depends on the vocal folds being able to open. However, people may find that they occasionally cough or choke when swallowing, particularly when swallowing liquids. The most noticeable symptom is the dramatic voice change: the voice become hoarse, breathy and weak. Speaking at loud volume or over background noise becomes very challenging and effortful.

Some cases of vocal fold paralysis resolve on their own, although it may take weeks to months. In other cases, it is almost always possible to achieve a normal or near normal voice using voice therapy alone or in combination with various types of surgery. No treatment should be undertaken until a thorough search for the cause of the problem is done. Sometimes, this will turn up nothing obvious. In such a case, the cause is deemed “idiopathic,” which simply means of unknown cause. Up to one-third of cases of vocal fold paralysis may turn out to be idiopathic. Conditions that must be eliminated as possible causes include lung cancer, particularly if the paralysis is on the left, and thyroid cancer.

Treatment must be individualized for every patient. Treatment depends upon the cause and duration of the paralysis, and the extent of disability it causes. In some cases, an additional diagnostic test called electromyography is recommended. This test may provide information about the likelihood that the nerve will recover on its own. Therefore, it can sometimes play an important role in treatment decision. The goal of treatment is to improve vocal fold closure, because all of the symptoms caused by vocal fold paralysis are due to incomplete vocal fold closure. Difficulty breathing is the most concerning complication of surgical treatment. Usually, this complication can be safely avoided, but this should be carefully discussed with your surgeon. A very brief summary of treatments is presented below. 

Voice therapy consists of exercises and techniques to help in vocal fold closure. Under certain conditions, other muscles can be used to increase closure. The voice therapist will teach you to take advantage of these. Unlike the surgical treatments, there is no risk to the airway with voice therapy. In cases where the gap between the paralyzed vocal fold and the working one is small, and sometimes in cases where the paralyzed vocal fold recovers only partially, voice therapy alone may be enough to achieve normal voice. Read more about specific goals and techniques of voice therapy for unilateral vocal fold paralysis.

Injection laryngoplasty is an operation that consists of injection of a material to add bulk to the paralyzed vocal fold so that it can make contact with the working one. The injection is done through the mouth, so that there are no scars, and usually requires general anesthesia. Traditionally, the material injected was Teflon, but experience has shown that it may cause benign growths called granulomas in a substantial number of cases, which can further damage voice and even narrow the airway, making breathing difficult. As a result, Teflon is generally avoided nowadays. Alternatives include collagen, fat from elsewhere in the body, processed connective tissue and other, newer substances. None of these are permanent, and they gradually re-absorb. This is not to say that the voice result cannot be permanent, as there are other variables involved. Speak to your physician about the details of the operation and the specific features of the various materials.

Medialization laryngoplasty describes an operation to implant a small piece of synthetic material, which is permanent (although removable) into the larynx. This serves to bring the vocal fold closer to the midline (medialize the vocal fold). It is generally performed under a local anesthetic in the operating room, though a small incision on the neck over the larynx. It may be combined with a procedure known as arytenoid adduction, which rotates the arytenoid to accomplish the same thing.

Reinnervation is surgery aimed at providing an alternate nerve supply to the vocal fold. It is not expected that this will cause the vocal fold to move again, but rather, that it will restore tone and bulk to a flaccid (limp) vocal fold. Observations have suggested that this may be enough to achieve a good voice result. Reinnervation is currently an investigational therapy, and is not used routinely in most centers. 

Because there are many options in the treatment of vocal fold paralysis, it is important to have a detailed discussion of your condition with your physician. In most cases, substantial improvement in laryngeal function can be achieved with treatment. There is no reason to endure the symptoms of unilateral vocal fold paralysis. 


Bilateral Vocal Fold Paralysis

When both vocal folds are paralyzed, they are usually immobilized close to the midline. Thus, closure is usually adequate, permitting acceptable voice and swallowing. However, breathing is usually very difficult. This difficulty increases with effort, and people with this condition may find that they are severely restricted in how far they can walk, or in how heavy a load they can carry. Often there is a wheezy noise when breathing, which can cause this condition to be mistaken for asthma. Asthma that fails to improve with appropriate medicines and inhalers requires that a physician examine the larynx and vocal folds.

Bilateral vocal fold paralysis almost always has an identifiable cause – it is rarely “idiopathic” or unknown. Causes include stroke or other neurologic condition (especially a childhood condition known as Arnold-Chiari malformation), thyroid cancer, or surgery such as major brain surgery or thyroidectomy.

The main issue in the treatment of bilateral vocal fold paralysis is whether or not the vocal folds are far enough apart to allow safe breathing. In many cases, the safest initial treatment is a tracheostomy – a breathing hole directly into the windpipe – to guarantee the airway until other plans are made. 

There are procedures to allow adequate airway and permit removal of the tracheostomy. However, all of these may cause some deterioration of voice quality, and sometimes, may create problems swallowing. This is because these procedures (such as arytenoidectomy and cordotomy) necessarily increase laryngeal opening.

Treatment of bilateral vocal fold paralysis often requires making some difficult choices. As is true in all voice disorders, nothing can take the place of a detailed discussion with your treatment team.


Spasmodic Dysphonia

Spasmodic dysphonia is an area of special expertise at the Institute. Spasmodic dysphonia is a frustrating, chronic condition for which no cure is currently known. However, it is only rarely associated with other diseases. In most cases, treatment can substantially improve symptoms, often resulting in a near-normal voice. Because, in the end, the affected person is the best judge of his or her voice function, honest and open communication between the doctor and the patient is essential in getting the most out of treatment and overcoming the disorder. At The Voice and Swallowing Institute, we believe that providing patients with information about this complex disease is an essential part of treatment. We’ve provided a great deal of information about the disease and its treatment in the document linked here, to help our patients discuss the best treatment.

FactSheet about Spasmodic Dysphonia Adobe Acrobat PDF icon


FAQs about Botulinum Toxin treatment of Spasmodic Dysphonia

What dose of botulinum toxin should I receive?

There is no standard Botulinum toxin dose. The dose for each patient with SD has to be customized for the patient due to the severity of his or her SD, the patient's voice demands and response to Botulinum toxin. The most common doses range from 1.0 to 2.5 units placed in the right and left vocal fold muscles for the treatment of AdSD.  The range for a unilateral injection for AdSD is typically from 2.5 to 10 units.

Should I be receiving unilateral or bilateral Botulinum toxin injections for my SD?

Once again, there is no standard rules for injecting Botulinum toxin regarding dose or number of locations.  Most commonly, bilateral injections are done for adductor spasmodic dysphonia. This is based on the notion that the disorder is bilateral and symmetric. However, in certain patients a unilateral injection may be preferable to minimize side effects. For AbSD, it is typical to inject either one side only or one side with a large dose and the other side a small dose. The patient will then return approximately three weeks following this procedure for a repeat injection, depending upon the response to the first injection.

What happens if I do not get treatment?

Available treatments for both forms of SD are able only to alleviate symptoms. Opting not to be treated has no effect on the underlying central nervous system disorder. Patients should only continue with treatment if they feel it is of benefit to them.

What are the common complications? 

Most complications of treatment are the result of either inaccuracy of injection or inappropriate dosing of botulinum toxin.If an injection is not well placed, the toxin may have no effect, or it may be reduced. This can be corrected by repeating the injection. 

Difficulty swallowing is probably the most common side effect. Since the larynx lies next to the entrance of the esophagus, and since laryngeal muscles are small and located fairly deep within the neck, toxin may inadvertently reach the esophageal or pharyngeal muscles. Weakening of these muscles, when added to the weakening of the vocal folds that results from treatment, can result in altered or impaired swallowing. Some temporary change in swallowing is reported by up to 17% of patients treated. In the vast majority of cases, this is more of an inconvenience than a danger. However, it is possible to impair swallowing more severely, and even theoretically to cause a lung infection from food entering the trachea (windpipe). Because the effect of botulinum toxin is temporary, it is usually necessary only to exercise caution while eating or drinking until the situation returns to normal. This is usually a matter of days or weeks, although in very rare cases, the problem may persist for the entire three months that the toxin has effect.  Difficulty with swallowing (especially liquids) following botulinum toxin injection is often most noticeable with the first injection and may decrease with subsequent injections.

Infection as a result of botulinum toxin injection performed in the office with normal attention to cleanliness and sterile technique has not been reported.

Minor bleeding and bruising at the injection site may occur, especially in those patients who take aspirin or blood thinners. Serious bleeding has not been reported.

There are side effects specific to each type of SD as a result of over-dosing the affected muscles. Because botulinum toxin has a very pronounced effect for the first several days, some minor unwanted effects are often seen following injection. In AdSD, these consist of a soft, breathy voice and difficulty when drinking liquids. Both of these occur because the treated vocal folds are not able to come together completely. In AbSD, there may be some breathing restriction because the treated vocal fold is not able to move aside fully. Administering too much toxin results in these effects becoming more pronounced and lasting longer. Obviously, great care is used in the treatment of AbSD so as to avoid breathing difficulties.

Side effects can be minimized and sometimes even eliminated by altering dose or injection pattern feedback. Information from the patient's experience with the previous injection is essential in making the necessary adjustments and each new injection should be preceded by a discussion between patient and physician about the effects of the previous one.

What about surgical treatments for SD?

Surgery for SD, like surgery for all dystonias, is a second-choice treatment, used in those cases in which botulinum toxin treatment is, for one reason or another, not possible, ineffective or poorly tolerated. This is because in the past, a disappointingly large number of patients have had a recurrence of symptoms months to years after surgery. In this respect as well, surgery for SD is like surgery for other dystonias.

The idea behind surgery for SD is the same as the one behind botulinum toxin treatment: the weakening of muscles that spasm. Surgeons initially cut or crushed the nerve to the vocal fold, called the recurrent laryngeal nerve. Despite encouraging initial results, about two-thirds of patients developed symptoms of SD again within three years. Furthermore, one vocal fold remained paralyzed by this procedure, a condition that has its own drawbacks (link to Vocal Fold Paralysis). Surgeons have also tried cutting the secondary nerve to the larynx, known as the superior laryngeal nerve; thinning the muscle of the vocal fold (myectomy); and manipulating the larynx so that the vocal folds lie farther apart (lateralization thyroplasty) or are under less tension (anterior commissure release). None of these techniques has resulted in satisfactory long-term control of symptoms.


For Further Information about Disorders of the Larynx Patient Associations & Support Groups

Relevant Medical Journal Articles

Pharmaceutical Companies

Because botulinum toxin use in the United States for the treatment SD is not FDA-approved, the manufacturers are not permitted to discuss information related to this use. Nevertheless, general information is available from each company.



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