What is spasmodic dysphonia?
Spasmodic dysphonia (SD) is a type of dystonia, a neurologic disease that causes involuntary movements. There are two types of SD. Adductor SD (AdSD) causes the vocal fold to come together (adduct) inappropriately during voicing, makes up about 85-90% of SD. Abductor SD (AbSD), on the other hand, makes the vocal folds come apart (abduct) during connected speech. These movements cause the symptoms which are discussed below.
SD usually affects adults, with a typical onset of symptoms in the 30s and 40s. The cause is unknown, and there do not appear to be any behaviors or environmental factors that increase the chance of contracting SD. It is not hereditary.
What are the symptoms of spasmodic dysphonia?
In AdSD, the vocal folds come together too tightly during speech, causing strained, strangled breaks in the voice. In AbSD, the vocal folds part, causing breathy or soundless breaks. In both cases, the voice breaks are irregular, and the severity of the symptoms can vary from day to day, or even over the course of a single day. It is typical for anxiety to cause symptoms to be more noticeable. People with SD often report that speaking with strangers or public speaking makes the voice worse. Almost all report that using the phone is especially challenging.
SD, like most dystonias, is task-specific. That is, it is only evident during one type of activity. Other laryngeal actions, like breathing and swallowing, are usually unaffected. Sometimes, the voice will even be fluent while laughing or singing, but not during connected speech. This feature, combined with the deterioration of the voice with anxiety, occasionally causes the disorder to be mistakenly attributed to psychiatric reasons. SD is not a psychiatric or psychological disease.
What does spasmodic dysphonia look like?
SD is a disorder of vocal fold movement, so the larynx has to be examined during voicing, and preferably during connected speech. The typical involuntary motions of the vocal folds are brief and spasm-like (hence the name “spasmodic”), and may occasionally be difficult to make out. This is especially true if the examination is being performed with rigid endoscopy, which requires the tongue to be pulled forward. Flexible fiberoptic laryngoscopy is better than rigid laryngoscopy for diagnosis of SD.
How is spasmodic dysphonia treated?
There is no cure for SD. Treatment is available to improve symptoms, and happily, that is almost always possible. It is important to understand that choosing not to get treated does not make the disease worse.
Laryngeal injections of botulinum toxin are the main therapy for SD. Botulinum toxin is a naturally occurring substance that weakens muscle for a period of about three months. It is best known as a cosmetic treatment to remove wrinkles, which it does by weakening forehead muscles, but botulinum toxin has probably accomplished the most good as a treatment for disorders of involuntary movement, like SD. Neither voice therapy, psychological/psychiatric treatment or medical treatment has by itself been useful in controlling SD symptoms.
Botulinum toxin has been used to treat SD since 1984. The principle behind treatment is to weaken the muscles that are behind the inappropriate motion. In the case of AdSD, these are the muscles that bring the vocal folds together, and in AbSD, the muscles that bring the vocal folds apart. The injection is performed through the skin of the neck as an office procedure. Afterwards, people can usually go on with the normal activities of the day.
In AdSD, because the muscles that bring the vocal folds together are weakened, injection is usually followed by a period of breathy, whispery voice and sometimes coughing while drinking liquids. If this is severe, or last beyond 7-10 days, the dose of botulinum toxin may be adjusted. In AbSD, the situation is more complicated, as overweakening of the muscles that part the vocal folds might result in difficulty breathing. For the reason, treatment in AbSD must be more cautious, and overall, symptom control is not as good as in AdSD.
Over the last thirty years, many surgeons have tried to treat SD by cutting or altering the nerve supply to the larynx. Early results have always been encouraging, but for complex reasons probably having to do with the brain abnormality underlying dystonia, the disorder returns in people after a few months or years. Currently, surgery is a second-choice treatment, best reserved for those people in whom botulinum toxin is, for one reason or another, not possible or ineffective.
More information can be obtained from the National Spasmodic Dysphonia Association (www.dysphonia.org/nsda), the Dystonia Medical Research Foundation (www.dystonia-foundation.org), or from Dr. Sulica’s office. The treatment of SD is a special interest of Dr. Sulica, and a focus of his practice.