Spasmodic Dysphonia

Spasmodic Dysphonia

National Organization for Rare Disorders, Inc.


It is possible that the main title of the report Spasmodic Dysphonia is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • CSD (Chronic Spasmodic Dysphonia)
  • Laryngeal Dystonia
  • Dysphonia Spastica
  • Spastic Dysphonia
  • SD

Disorder Subdivisions

  • Abductor Spasmodic Dysphonia
  • Adductor Spasmodic Dysphonia

General Discussion

Spasmodic dysphonia is a voice disorder characterized by momentary periods of uncontrolled vocal spasms, tightness in the throat, and/or recurrent hoarseness. At certain times, affected individuals must make a conscious effort to speak. The most frequent sign of this disorder is a sudden, momentary lapse or interruption of the voice. Spasmodic dysphonia is a form of dystonia, a group of neurological movement disorders characterized by involuntary muscle spasms.

There are two types of spasmodic dysphonia: Abductor spasmodic dysphonia and the more common adductor spasmodic dysphonia. The cause of spasmodic dysphonia is not known.


Spasmodic dysphonia is a speech disorder caused by neurological dysfunction. The most frequent symptom of this disorder is a sudden, momentary lapse or interruption of the voice. Other common symptoms include momentary periods of uncontrolled vocal spasms, tightness in the throat, and/or recurrent hoarseness. Affected individuals must make a conscious effort to speak.

There are two types of this disorder, adductor spasmodic dysphonia and abductor spasmodic dysphonia. Adductor spasmodic dysphonia, the more common type, occurs when the vocal cords draw together, sometimes becoming locked. Abductor spasmodic dysphonia occurs when the vocal cords draw apart. In some cases, affected individuals may exhibit both types of SD. Both types cause difficulty in speaking.

Adductor spasmodic dysphonia is characterized by a tight, strained, harsh voice, while abductor spasmodic dysphonia is characterized by breathy, whispered speech, and loss of the voice for short periods of time (aphonia). In most cases, singing and laughing remain relatively unaffected. Individuals affected by the abductor type may have difficulty controlling speech after certain sounds (e.g., "P," "T," and/or "K").

In some cases of chronic spasmodic dysphonia, symptoms gradually progress for the first two years then generally stabilize. In most cases, symptoms do not progress into other forms of dystonia. The disorder usually remains chronic without marked changes over a period of years, although symptoms may worsen with stress. The number and severity of symptoms varies widely among affected individuals.


The exact cause of spasmodic dysphonia is not known. Some researchers believe that the condition originates in a part of the brain called the basal ganglia. Dystonia may also be caused by trauma to the head and/or exposure to certain drugs or toxins.

When people speak, nerve impulses from the brain send messages to the vocal cords and the muscles that control the voice. In individuals with spasmodic dysphonia, these messages are abnormal. This results in the inappropriate vocal cord spasms that characterize this disorder.

Spasmodic dysphonia is a subtype of a group of neurological movement disorders known as the dystonias. The dystonias include such disorders as blepharospasm, cervical dystonia (which affects the neck), and/or generalized dystonia, which affects the limbs, torso, neck, and face. (For more information on these disorders, choose "Dystonia" as your search term in the Rare Disease Database.)

Affected Populations

Spasmodic dysphonia occurs more often in females than males. Onset is usually between 20 and 60 years of age.

Standard Therapies

The diagnosis of spasmodic dysphonia usually includes inspection of the voice box (laryngoscopy) to rule out structural abnormalities of the vocal cords such as nodules, polyps, or tumors. The diagnosis may require speech pathology, otolaryngology, and neurology consultations. Laryngeal electromyogram (EMG) and nuclear magnetic resonance imaging (NMRI) have been used to identify any associated neurological disorders.

Botulinum toxin therapy is the standard treatment for spasmodic dysphonia. The drug is injected into the vocal cords every three or four months, to reduce vocal cord spasms. Some patients can wait longer between injections before symptoms return and more injections are needed. The degree of effectiveness of Botulinum toxin will differ in each individual case. Botulinum toxin is approved by the Food and Drug Administration (FDA) for cervical dystonia and is widely used off label to treat all forms of dystonia. Botulinum toxin is manufactured by Allergan Pharmaceuticals (as BOTOX©) and Elan Pharmaceuticals (as MYOBLOC).

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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