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.

Diagnosis of SD made from a person’s description and demonstration of the problem, and from observation of the vocal folds during voicing. There is no specific finding on any test that identifies SD. Ultimately, the diagnosis is a matter of expert opinion.