Information for patients with neurologic spasms of the vocal folds.


Spasmodic dysphonia is a neurologic disorder. Medical science does not yet know the cause or exactly how the disorder works. There seems to be some emerging research that points to a problem in the feedback loop between the brain and the organ with the dystonia – in this case the voice box. Due to a problem with this feedback loop, there is over-control with resultant spasms or overly tight muscle contractions. Research with PET scans has shown a decrease in activation of the brain once treatment has decreased the effortfulness of using the associated muscle. Despite this lack of knowledge of the etiology, there is a good treatment for the symptoms of the disorder.

Focal dystonias

Spasmodic dysphonia is one type of a family of disorders called focal dystonias. When a single muscle or small group of muscles contract spontaneously and irregularly without good voluntary control, those muscles are dystonic. While there are dystonias when a large number of muscles or a complete region of the body is involved, focal dystonias are limited to a small area or single muscle. Examples include torticollis, where a spasm of a neck muscle causes the head to rotat, blepharospasm, when the muscle around the eye spontaneously twitches, and writers cramp, when the muscles of the hand spasm. Spasms of the muscles in the voice box are a laryngeal dystonia. Interestingly dystonias are not disorders of muscle tone that the name [dys] [tonia] might seem to imply. Early in the twentieth century, a physician thought the disorders were a problem with muscle tone and the name has stuck even though etymologically incorrect.

Laryngeal dystonias

There are several types of laryngeal dystonias. The most common type is when the muscles that bring the vocal folds together for speaking intermittantly spasm. Since the voice box serves several functions, including speaking, breathing, and preventing food from getting into the lungs when swallowing, laryngeal dystonias can affect more than the voice. When the voice is the primary site affected, the laryngeal dystonia is called spasmodic dysphonia. It has also been referred to as spastic dysphonia.

  • ABductor spasmodic dysphonia
  • ADductor spasmodic dysphonia
  • Respiratory dystonia
    Respiratory dystonia is from spasms of the vocal fold muscles belonging to the ADductor group but instead of spasming during speaking, they spasm during breathing. These spasms create noisy and difficult breathing. This involuntary noise is produced despite not wanting to make a noise. 
    The main approach to treating this disorder is to weaken the muscles that bring the vocal folds together leaving more room for breathing, sometimes at the expense of a good voice. The two ways to weaken the muscles are Botox injections into the spasming muscles or cutting a portion of the nerve going to the muscles. It is also possible to bypass the nerve problem and create a better breathing passage with a tracheostomy or by removing a portion of one of the vocal folds.
    Botox injections to the vocal cord muscles are a reasonable approach, since when they wear off. If the injection is not adequate, one has the opportunity to try again. The other treatments are more permanent. If the injections are working, but not well, one can study the muscles further with a technique called electromyography (EMG) to determine which of the several voice box muscles is most affected and direct the injections towards that or those muscles.

Is it psychologic?

As recently as the 1970s most people thought that spasmodic dysphonia was a psychologic disorder. Though this has been proven not to be the case, many people still tend to be diagnosed as having a psychologic disorder. This happens for several reasons. Spasms cannot clearly be seen like a polyp or nodule could be so are often missed on a visual examination. Since spasmodic dysphonia is an uncommon disorder when compared to something such as heart disease, many physicians are not familiar with it. If they have never heard of it, physicians will not diagnose it. Spasmodic dysphonia presents in several variations and may not be a single disease. Spasmodic dysphonia tends to vary in it's severity daily and weekly, so both patient and physician may question how real the illness really is.

Some of the most common complaints or symptoms patients have include the following:

  • I got a cold/bronchitis/laryngitis and it did not go away like it usually does.
  • My voice varies all the time.
  • It is a struggle to get the words out.
  • I can sing easily but I cannot talk easily.
  • If I speak at a higher pitch, the spasms go away.
  • I hate to use the phone.
  • I have good weeks and I have bad weeks.
  • I have had to give up working, speaking, teaching, etc.

Sensory tricks

Dystonias often can be relieved by sensory tricks, perhaps at first glance making the patient or examiner believe the problem is psychologic. A better explanation is probably that some sensations cause an input to the brain that changes the impulses causing the spasms. While examining a patient's throat, a physican will often hold the tongue and this may relieve the spasms. Spraying numbing medicine on the back of the throat can change the spasms temporarily.


The mainstay of therapy starting in the late 1980s has become botulinum toxin injections into the muscles that are spasming. The injections are temporary, causing a beneficial effect for about four months. Other treatments tried include cutting a nerve to the voice box and attaching another nerve, changing the shape of the voice box, and speech therapy. While each of these treatments have been successful in some people, they have not been successful in others. Additionally, other physicians and scientists have not been able to consistently repeat the successes described by some.

Watch a video covering various types of injections (Botox as well as other substances).

Botulinum toxin A

Botulinum toxin A is a protein produced by the bacteria botulinum. It is indeed the same one that causes food poisoning. Botulinum toxin A has been produced primarly by Allergan Corporation under the trade name Botox. Other variations of this protein are being developed by other corporations. The medication works by weaking the muscle into which it is injected. It interrupts the junction of the nerve with the muscle. Nerves, fortunately or unfortunately, are very good at re-sprouting and making new attachments to muscle. Thus the botulinum injection is only temporary because over several months, about four, the nerve hooks itself back up to the muscle. This is good if you have food poisoning since your muscles will work again, and not so good if you have spasmodic dysphonia since you need to make a return trip for another injection.

The dose of botulinum toxin A depends on both how the injection is done and on some unknown property of the disease. One or both muscles of the paired voice box muscles may be injected. Dosage does not depend on severity of the spasm, age, sex, or weight of the patient, or any other factor of which we are presently aware. Thus the first injection a patient receives is something of a trial since it may be a bit too much or not enough.

To some extent the larger the dose, the longer the duration of the beneficial effect. Although, on average, this is limited to about four months. Additionally the larger the dose, the longer the initial breathiness. Depending on the patients needs, a dose is ultimately chosen that balances the initial side effects while obtaining a reasonable duration of benefit. 

Further information

National Spasmodic Dysphonia Association (NSDA) produces a newsletter and sponsors annual conferences. Most larger cities have a local support group and the NSDA has a list of these. Since dosages of botulinum toxin are small and the medication is expensive, patients are usually treated on the same day. This can be an opportunity to meet other patients with the disorder in the waiting area.

Here is a video from a lecture I gave to the NSDA some years ago.

See list of spasmodic dysphonia resources.

Physicians who may be performing injections in your area.

Medical diagnostic information

Information for physicians, medical students, residents and other voice professionals using the symptom complexes and the three part model for voice disorder diagnosis.