Overview | Understanding the Disorder | Symptoms | Diagnosis | Treatment

Image "A"Key Glossary Terms

Spasmodic Dysphonia (SD)
A voice disorder resulting from involuntary movements (spasms) of the voice box muscles.

A nervous system problem that causes involuntary movement; dystonia is not a psychological problem; SD is a type of dystonia

Adductor SD (Ad-SD)
Spasms in muscles that close vocal folds, which interrupt speech and cause strained or strangled voice breaks

Abductor SD (Ab-SD)
Spasms in muscles that open vocal folds, which interrupt speech and cause breathy or soundless voice breaks


In Brief
Spasmodic dysphonia is a voice disorder resulting from involuntary movements (or spasms) of the voice box muscles. These spasms interrupt normal voice (dysphonia) in “abrupt spurts” with a strained, strangled voice, with breathy, soundless voice, or with a mixture of both.

  • Spasmodic: spasms or involuntary movements
  • Dysphonia: abnormal voice

A Neurological Disease
SD is a type of dystonia, a disorder of the central nervous system that causes involuntary movement of the vocal folds during voice production.
SD is not a psychiatric or psychological disease.
Swallowing and breathing, the other important functions of the voice box, are almost never affected.

Three Types of Spasmodic Dysphonia

Type 1: Adductor SD (80% to 95% of cases)
What Happens: Vocal folds come together (close) tightly at the wrong time during speech, making it difficult to produce voice
How the Voice Sounds: Strained, strangled breaks while speaking

Type 2: Abductor SDM
What Happens: Vocal folds move apart (open) at the wrong time during speech, causing air leaks
How the Voice Sounds: Breathy or soundless breaks while speaking

Type 3: Mixed SD
What Happens: Combination of abductor and adductor SD
How the Voice Sounds: Sometimes strained, strangled breaks; sometimes breathy or soundless breaks

Unknown Cause, but Treatment Can Improve Voice Problem
For spasmodic dysphonia, like all dystonias:

  • The cause is unknown
  • There is no specific test for diagnosis
  • There is no known cure–but treatment can and does improve symptoms

Mainstay of Treatment
Botulinum toxin injections into muscles of the voice box can alleviate symptoms – although relief is only temporary. Treatments are usually repeated approximately every three months.

Outlook on Treatment
In almost every case of spasmodic dysphonia, symptoms can be improved with treatment.

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