Spasmodic Dysphonia

Dystonias are most often characterized by a sustained contraction that produces a torsion or twisting action, and can also be associated with spasmodic contractions. The exact cause of dystonias is still unknown, although the disorder is felt to originate in part of the brain called the basal ganglia. The basal ganglia is important in the initiation and control of movements in the body. Along with dystonia, other movement disturbances that arise from problems in the basal ganglia include Parkinson's disease, Huntington's disease, and Wilson disease.

There are several different ways to classify dystonias. For example, dystonia can be classified by the groups of muscles involved using the following terms:

• Generalized
• Focal
• Segmental

Although dystonias do not always fit neat categories, generalized dystonias usually involve a large number of muscle groups, while focal dystonias affect a specific group of muscles. Falling somewhere in between are the segmental dystonias.

Generalized dystonia is also called idiopathic torsion dystonia. It usually begins during childhood in one arm or leg and over time progresses to involve other extremities. Walking may be affected first, and eventually most other muscles become involved.

Focal dystonias affect a small number of muscles. Many of them occur in the head and neck region. The most common ones are:

• Blephrospasm, rapid blinking of the eyelids.
• Torticollis (also called wry neck), turning of the head to one side.
• Spasmodic dysphonia, strained or breathy speech.
• Oromandibular dystonia, involuntary jaw opening and tongue movement.
• "Writers Cramp," a dystonia affecting the hand and arm muscles, usually occurring with intended movement of these muscles.

There is no specific test for dystonias, and the diagnosis is often made based on the clinical signs and symptoms. Diagnosis may be difficult because the symptoms may resemble those of other neurological disorders.

Certain dystonias are known to be genetic. These forms of dystonia are most often inherited in an autosomal dominant pattern with variable penetrance. This means that 50% of the offspring of individuals with carry the gene for dystonia, but a variable percentage of them will actually develop dystonia. A gene for idiopathic torsion dystonia has recently been discovered. The gene, known as DYT1, is located on chromosome 9.

There are different forms of treatment for dystonia, depending on which muscles are involved and the extent of the disease. On other pages on this site, a description of treatment for spasmodic dysphonia using injections of botulinum toxin (Botox) is given.

For more information about dystonias, look also at the Dystonia Medical Research Foundation website.

Introduction spasmodic dysphonia (SD) is a type of disease known as a dystonia. A dystonia is a disorder of the central nervous system in which there is increased contraction of the muscles. This disorder can affect many muscles, which is called a generalized dystonia, or it can affect just one or two muscle groups in which it is called a focal dystonia.

Spasmodic dysphonia is a dystonia in which affects only the muscles of the larynx. Other examples of focal dystonia are torticollis (wry neck), blephrospasm (eye-twitching), and writer's cramp.

The exact cause of this dystonia is currently unknown but is believed to involve a region deep in the brain called the basal ganglia. In spasmodic dysphonia, this area of the brain sends incorrect messages to the muscles controlling the movement of the vocal folds, causing them to contract inappropriately.

There are several types of spasmodic dysphonia. The most common is called adductor SD and it occurs when the muscles that bring the vocal folds together contract too strongly. "Adduction" is the term used when the vocal folds come together. Opening of the vocal folds is called "abduction." In adductor SD the voice has a very strained or strangled sound, with occasional breaks when the air cannot escape. These breaks are most evident in words that begin with vowels.

Abductor SD is less common. In this disorder the spasms occur in the muscles that open the vocal folds. As a result, it is difficult to bring the vocal folds together to produce vowels sounds.

There can also be a mixed spasmodic dysphonia affecting both opening and closing of the vocal folds, and a version dominated by tremor.

Spasmodic dysphonia is worsened in stressful situations, and therefore may be mistaken attributed only to stress. (It is important to remember that there certainly can be severe voice disorders arising from stress alone; however, these type of voice disorders are best treated with speech therapy and not with Botox.) SD also is often worse on the telephone. It is better with non-verbal vocalization like sighing and laughing and is less severe with singing or a high-pitched voice.

Spasmodic dysphonia is not very common and as a result many physicians are not familiar with it. As a result, individuals with SD often are told that their voice disorder is due to nervousness, laryngitis, reflux, etc. However, voice disorders can from SD can at times sound like these and other conditions, so the diagnosis of SD is not always clear-cut. Some tests, such as laryngeal electromyography, may be useful, but the diagnosis is most often made by a combination of patient history and careful examination of the larynx.

The most widely used form of treatment for spasmodic dysphonia is injection of a long-acting muscle relaxant called Botox.

Spasmodic dysphonia (SD) is a type of neurologic disorder called a dystonia. It affects the muscles of the larynx. This page describes SD and its treatment using a medication called botulinum toxin (Botox).

A general description of dystonias is also available. The basic problem in SD is that the muscles of the larynx contract too strongly during speech. The muscles themselves are normal, but their neurological control is abnormal. The cause of SD is believed to originate in a part of the brain called the basal ganglia.

The are several different types of SD. In the most common variant, the muscles that close ("adduct") the folds contract too tightly. This condition, called adductor spasmodic dysphonia, produces a strained or strangled sound to the voice. In a less common variant the problem is with the muscles that open, or "abduct" the vocal folds. Some individuals have mixed SD, or characteristics of both adductor- and abductor-type dystonia. SD can also be associated with tremor.

Botox can minimize the symptoms of SD when injected into muscles of the larynx. This page will provide some information about how botox works, the general technique of the botulinum toxin injections, as well as some of the possible complications

The image to the right shows a cross section of the vocal folds, viewed from above. For the more common adductor SD, the botox is usually injected into the thyroarytenoid muscle. In a few cases, better results may be obtained with an injection into a muscle called the lateral cricoarytenoid.

For the less common variant of abductor SD, the muscles that open the vocal folds must be weakened. This muscle is called the posterior cricoarytenoid and runs from the cricoid to the arytenoid. (The arytenoid is a small piece of cartilage attached to the back of the vocal folds.)

Botulinum toxin weakens the injected muscles. Although the source for the dystonia appears to be at the base of the brain, we treat the disorder by injecting the involved muscle. It is important to remember that Botox does not treat the cause of dystonia but provides temporary relief. Although the muscle is still receiving abnormal signals from the brain, it cannot contract as strongly as before and provides relief.

During the Botox injection, you will lie down in an examination chair with your head extended back over a pillow. It is helpful if you wear a shirt that has an open neck. A local anesthetic is injected first so that the skin and sensitive areas near the vocal folds are not stimulated when the needle is placed.

The Botox is injected through a small needle connected by a wire to an electromyography (EMG) machine that records the activity of the muscle. The placement of the needle into the muscle is verified by the electrical signals shown on the EMG machine. Once the EMG signal indicates that the needle is in the correct muscle, the medication is injected. There is minimal discomfort, and the entire procedure takes about 15 minutes.

Botox prevents the release of one of the body's neuro-transmitters at the connection between the nerve and the muscle, causing weakness of the muscle. Over time, the connection between the nerve and the muscle grows back, and therefore, the effect of Botox is temporary. In most cases, the effect of Botox lasts 2-4 months.

Although Botox is derived from the botulinum organism, the organism itself is never injected. The material that is injected is the muscle relaxant produced by the botulinum bacteria. For SD, a tiny amount is injected since the muscles of the larynx are so small.

The severity of the disorder in everyone is different, so the dosage for the first few injections is calculated by estimating the degree of dystonia. Sometimes too little is given and relief is minimal. If a patient is very reactive to the botulinum toxin, an exaggerated response leading to significant weakness can be seen. After one or two sessions, the right dose for everyone can usually be found.

After the Botox injections

You should not eat or drink anything for 45-60 minutes after the injection. Anesthetic numbs the throat and may cause coughing after swallowing. Some patients may cough up some blood-tinged sputum during the first 24 hours. A small amount of bleeding may occur when the needle is inserted, and this can appear in the sputum. The neck may be sore for a day or two from having the needles inserted, but this usually passes without any intervention. After a Botox injection, do not take aspirin or ibuprofen. These interfere with blood clotting and can lead to bleeding.

The effects of Botox usually begin 12-24 hours after the injection. It is almost always noted by 48-72 hours and the full effect is established usually by one week, but sometimes as late as two weeks.

Botox injections almost always cause an exaggerated effect during the first week or two. This can result in a very breathy or high-pitched voice. It will wear off after about two weeks and the more therapeutic effects of Botox become evident.

Possible complications

As a protective measure, the vocal folds close tightly when we swallow to help prevent food from entering the lungs. This is weakened after Botox injections. In most cases this causes minimal or no problems. However, it there is an exaggerated effect, there can be symptomatic aspiration. In rare cases, a feeding tube must be placed to provide nutrition. After injection of one posterior cricoarytenoid muscle, a laryngeal examination is usually performed prior to injection of the other side to be sure that the muscle that move the vocal folds apart are working well. If both muscles are weakened, this can cause breathing problems. Some individuals who receive very large injections of Botox for conditions such as torticollis (wry neck) have developed antibodies to the Botox. This limits the effectiveness of the medicine, requiring larger doses. However, the dose of Botox used in laryngeal dystonia is much smaller than torticollis, and antibody formation is seldom seen in spasmodic dysphonia.