What is Spasmodic Dysphonia?
Spasmodic dysphonia is a voice, or speech, disturbance caused by involuntary movements of one or more muscles of the larynx (voice box). It is a chronic condition, usually appearing in individuals of 30 to 50 years of age; mostly affecting females.
There are two main types of spasmodic dysphonia: adductor spasmodic dysphonia and abductor spasmodic dysphonia.
In adductor spasmodic dysphonia, sudden involuntary muscle movements (spasms) cause excessive closing of the vocal folds (or vocal chords). These spasms interfere with airflow and stop the vocal folds from vibrating and producing a voice. In mild forms of adductor dysphonia, jerky or choppy breaks in speech are heard in every couple of sentences whilst in moderate forms, the voice is constantly breaking or bursting. In the most severe form, as very little air can be forced through the vocal folds, individuals have a voice that sounds constantly strained, full of effort and low in volume.
Abductor spasmodic dysphonia occurs less frequently. In this form of spasmodic dysphonia, the muscle spasms cause the vocal folds to open. As a result, the vocal folds are unable to vibrate, and air from the lungs is able to escape during speech. In mild to moderate forms, individuals may sound breathy and may have trouble starting a sentence. In more severe forms, as speech becomes more difficult, individuals may need to whisper as it requires less effort.
Surprisingly, spasmodic dysphonia is often absent during reflex and emotionally driven laryngeal (voice box) functions such as swallowing, coughing, laughing or crying.
What Causes Spasmodic Dysphonia?
The exact cause of spasmodic dysphonia is unknown. Onset is gradual, over one to two years, and usually occurs after an upper-respiratory tract infection, emotional stress or an injury/excessive strain on the voice box.
What are the signs and symptoms of spasmodic dysphonia?
Early signs of spasmodic dysphonia are: increased effort in speaking, loss of voice, and trouble controlling pitch of voice. These symptoms often first appear during stressful periods, and only occur during speech. As the disorder progresses, however, all voluntary aspects of voice use are affected. Symptoms become worse with prolonged speaking, practice or performance, and symptoms are generally at their worst at the end of the day; whilst reflex or emotional voice actions continue to remain unaffected.