Spasmodic dysphonia (SD) is a voice disorder. It occurs when the muscles of the throat freeze or go into spasms. Words are strangled and strained. Or, they don’t get out at all. Sounds are distorted. SD is a form of dystonia . In dystonia, the muscles involuntarily tighten and twist.


Spasmodic dysphonia affects the throat muscles.
© 2009 Nucleus Medical Art, Inc.


The exact causes of SD are unknown. It is categorized as a disorder of the central nervous system. Causes of dystonia, the greater condition, have been linked to damage to a part of the brain called the basal ganglia. These are structures deep within the brain that help control movement.

Risk Factors

These factors increase your chance of developing SD:

  • Degenerative brain diseases (eg, amyotrophic lateral sclerosis )
  • Another movement disorder (eg, tardive dyskinesia )
  • Family history of SD—In some families, a gene on chromosome 9 may be connected to SD.
  • Brain infection (eg, encephalitis )
  • Exposure to toxins or certain medications (eg, phenothiazines)
  • Gender: female
  • Age: between 30-50 (typical age group when the first signs appear)

Tell your doctor if you have any of these risk factors.


If you have any of these symptoms do not assume it is due to SD. These symptoms may be caused by other conditions. Contact your doctor if you have any of these:

  • Squeaky, strained speech
  • No speech at all
  • Speech with the wrong pitch and tone
  • Breaks in speech
  • Breathy voice


Your doctor will ask about your symptoms and medical history. She will also do a physical exam. Tests may include:

  • Blood and urine tests to find toxins
  • DNA testing for related genes
  • MRI scan —a test that uses magnetic waves to make pictures of structures inside the brain
  • CT scan —a type of x-ray that uses a computer to make pictures of structures inside the brain

Your doctor may refer you to a team of specialists, including:

  • Neurologist—to evaluate your brain function
  • Speech pathologist—to evaluate your speech and how it’s produced
  • Otolaryngologist—to evaluate your vocal cords

Your doctors will determine which main type of SD you have:

  • Adductor spasmodic dysphonia—spasms cause muscles to stiffen and close
  • Abductor spasmodic dysphonia—spasms cause muscles to spastically open
  • Mixed spasmodic dysphonia


Talk with your doctor about the best treatment plan for you. Treatment options include the following:

  • Local injections of botulinum toxin (Botox) to weaken and calm the muscles
  • Medication to increase dopamine, a chemical in the brain that influences muscle movement
  • Speech therapy techniques to relax muscles
  • Brain stimulation using electrodes to prevent muscles from freezing and going into spasm
  • Counseling to help deal with the condition
  • Surgery to cut or remove nerves connected to the vocal cords (severe cases)


Since the causes are unknown, it is difficult to prevent SD. Talk to your doctor if you have any of the risk factors.