Laryngeal Dystonia

Spasmodic dysphonia or SD is a focal dystonia that affects the vocal cords. It usually becomes apparent between ages 30 to 50 and affects women more frequently than men. There are two distinct forms of SD: adductor SD and abductor SD.

Adductor SD is the more common form of this condition and is characterized by contraction of certain vocal muscles that draw the vocal cords together during speech. This causes the voice to have a restricted, strangled, or hoarse quality. Vocal expression is often interrupted by sudden, short pauses followed by abrupt bursts of speech, which may become less and less understandable. In most patients, singing is not as severely affected as speech.

In abductor SD, contractions of certain muscles that draw the vocal cords apart causes the voice to have a breathy, whispering quality. Patients tend to "run out of air" as they attempt to speak and are unable to speak loudly. As a result, their speech may also be difficult to understand.

Symptom onset is typically relatively gradual. Initial signs often include increased effort during speech and the loss of voice control that occurs with emotional stress. The condition tends to stabilize after about 1 to 2 years of increasing symptom severity. Speech may temporarily improve subsequent to sneezing or yawning. In some patients, sensory tricks, such as pressing the hand on the abdomen or the back of the head, may temporarily relieve symptoms.

In up to 30 percent of patients, dystonia may also affect other body regions, particularly the muscles of the neck or head. In addition, SD is sometimes associated with dystonic tremor of the vocal cords that may develop prior to the onset of laryngeal dystonia. Dystonic vocal cord tremors need to be distinguished from essential tremor (ET), a common neurologic movement disorder that is often associated with tremor of the hands or head.

	Limb Dystonia