Published: Feb. 27, 2008
Updated: Aug. 4, 2011
Spasmodic dysphonia (SD) occurs in the vocal cord muscles when one or more muscles of the larynx move involuntarily. SD is a neurologic voice problem, not associated with how someone uses his or her voice.
SD is usually slow in onset and progression, and usually does not impact parts of the body other than the vocal folds.
Symptoms of SD will fluctuate in severity from day-to-day. Often people report their voice symptoms are sometimes worse for no obvious reason, but their voices are usually made worse by stressful situations.
Most people with SD typically have better voices while singing or speaking in higher pitches -- for example, the way you might speak to a baby.
The most common type of SD is the adductor type, in which the vocal cords have spasms that bring them together too strongly. People with this type of SD often have a strained or strangled quality to their voice and increased effort to speak.
Typically, people with adductor SD have problems with sounds like "b," "d," or "g" sounds (as in "baby," "dog," or "girl").
Abductor SD is a much less common type of SD. The vocal cords spasm apart, resulting in a loss of voice or sudden loss of volume in the middle of a word or sentence. Typically, these people have trouble with the "p," "t," or "sh" sounds (as in "Peter," "Tom," and "shell").
Sometimes people may have both adductor and abductor symptoms or a vocal tremor. A team of otolaryngologists (ear, nose, and throat physicians) and speech pathologists at the Duke Voice Care Center will work together to accurately diagnose and treat SD.
SD usually responds best to medical treatment, but often people will benefit from voice therapy as well. Treating SD requires an integrated evaluation by the otolaryngologist and speech pathologist to ensure that the diagnosis is accurate and to ensure the best treatment is recommended.
Treatment of SD is aimed at restoring the "balance" of the muscles. In some cases, weakening of specific muscles in the voice box can improve the voice.
In the last 15-20 years, botulinum toxin A (BOTOX) has been effectively used to temporarily weaken or paralyze specific muscles. In SD, either the vocalis muscles or the posterior cricoarytenoid muscles are weakened by botulinum toxin A, improving the voice and decreasing the effort to speak. The type of SD that a person has determines which muscle needs to be injected.
Botulinum toxin A is injected through a small needle using signal guidance provided by a neurologist because these muscles are tiny, and the method ensures a more precise injection.
Botulinum toxin A is not a cure for SD but provides temporary improvement in voice symptoms. People typically need to have this treatment repeated every four to six months to maintain good voice quality. Duke University Medical Center has staff with specialized training in the use of botulinum toxin A for the treatment of SD and other dystonias of the head and neck.
If you do not live within driving distance to our center, make sure you find a voice team who can appropriately treat SD. The National Spasmodic Dysphonia Association provides a list of physicians who treat this condition.
It is important that you find out how much experience your voice team has in treating people with SD so that you receive an accurate diagnosis and treatment by skilled providers.
People with SD will often benefit from voice therapy to minimize the impact of the disorder or to address vocal strain. They often develop vocal strain to compensate for the voice problem, as a way to "push" the voice out. Most people do not realize, however, that strain can cause the SD symptoms to become more pronounced.
Voice therapy is beneficial in helping people maximize the benefit of the botulinum toxin A injection and use the voice in the most efficient way possible. Most people with SD will only need a few session of voice therapy to improve.
The most important points to remember about SD include: