Spasmodic Dysphonia
Everyone has experienced times when their voice was a bit scratchy or hoarse when sick with a cold or when allergies act up. People with spasmodic dysphonia (SD), a chronic and debilitating voice disorder, experience this kind of voice daily. They are frequently asked-- "What's wrong with your voice?"
Spasmodic dysphonia (SD) is a type of neurologic disorder classified as a dystonia. Recently, the term focal laryngeal dystonias is used to describe this set of characteristics that define SD. Laryngeal dystonias have characteristics in common with other dystonias such as torticollis and writer's cramp. In the case of focal laryngeal dystonias, vegetative phonation (e.g., laughing, crying) is often unaffected. Patients may also speak normally when first rising in the morning, and may be able to sing without the same degree of strain, hoarseness or breathiness. SD is a task-specific laryngeal movement disorder related to the use of the voice for speaking.
The basic problem in SD is that the muscles of the larynx contract too strongly during speech (hyper-adduction or hyper-abduction). The muscles themselves are normal in appearance at rest, but their neurological control is abnormal. While the vocal cords of people with spasmodic dysphonia may appear normal, when phonation (voice) is initiated, the vocal cord movement pattern is uncontrollable. Although little is known about the cause of SD, it is likely the result of faulty central neural integration. Some researchers speculate that the origin is in a part of the brain called the basal ganglia.
There are several different types of SD. In the most common variant the muscles that close ("adduct") the folds contract too tightly. This condition, called adductor spasmodic dysphonia (AB-SD), produces a strained or strangled sound to the voice.
A less common variant, abductor spasmodic dysphonia (AB-SD) is the over contraction of the muscles that open, or "abduct" the vocal folds. This recreates a voice quality that is weak and breathy. There are “breathy spasms” which interrupt the smooth, fluid flow of speech.
Some individuals have mixed SD, or characteristics of both adductor- and abductor-type dystonia. People with SD might also experience a tremor in their voice.
This rare voice disorder affects more women than men and is found to strike people in all walks of life. It typically occurs between the ages of 30 and 50 years but cases have been seen in children and adolescents. Onset of the SD voice symptoms often follow an upper respiratory infection or periods of high stress.
However, SD is clearly NOT a psychological condition. But, as with most other voice disorders, stress usually does make SD worse. The underlying condition may easily be confused with other voice disorders called "muscle tension dysphonias, (MTD)," (which improve with voice therapy). It must be emphasized that SD is an organic, neurological problem.
Voice therapy or vocal rehabilitation is the first order of treatment--after the patient has been examined by an otolaryngologist (Ears, Nose & Throat physician) who has expertise in the treatment of voice disorders.
Voice therapy typically consists of systematized exercises and strategies to rule-out the more common voice disorders such as MTD. Botox treatment is also a common treatment choice. It appears that for most patients with the AD-type of SD both these treatments options offer them the best solution to their voice disorder.
For additional and more detailed information about Spasmodic Dysphonia contact:
National Spasmodic Dysphonia Association
One East Wacker Drive, Suite 2430
Chicago, IL 60601-1905
Voice: (800) 795- NSDA (6732)
Fax: (312) 803-0138
E-mail: NSDA@dystonia-foundation.org
Website: www.dystonia-foundation/NSDA
For additional information on this topic or other speech, language, or hearing disabilities, contact the American Speech-Language-Hearing Association website at http://www.asha.org
The National Institute on Deafness and Other Communication Disorders (NIDCD) is one of the Institutes that comprise the National Institutes of Health (NIH). NIH is the Federal government's focal point for the support of biomedical research. http://www.nidcd.nih.gov/health/pubs_vsl/spasdysp.htm
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