Spasmodic Dysphonia

Spasmodic dysphonia is a voice disorder caused by involuntary spasms (focal dystonia) of one or more muscles of the voice box (larynx). Spasmodic dysphonia can affect anyone at any age, but tends to be diagnosed most often in individuals between the ages of 30 and 50. It is estimated that 50,000 individuals in North America are affected by spasmodic dysphonia, but the actual number affected may be higher due to misdiagnosis or unrecognized cases.

Causes
It is not known what causes spasmodic dysphonia. In the past, the disorder was thought to be all in the individual’s mind (psychogenic). Researchers now know that spasmodic dysphonia is a nervous system (neurological) disorder, and they have identified a gene on chromosome 9 as being associated with it.

In some individuals the symptoms of spasmodic dysphonia begin after a bad cold or respiratory infection, injury to the larynx, overuse of the voice, or stress. The individual may have other types of dystonia such as excessive eye blinking (blepharospasm), neck muscle spasms (torticollis), or the jaw muscles, lips, and tongue may be affected (oromandibular dystonia). Parts of the body, such as a finger or the hand, may quiver or shake (have tremors).

Symptoms
There are two main types of spasmodic dysphonia, adductor and abductor. The symptoms for each type are:

Adductor spasmodic dysphonia
• words are cut off or difficult to start
• speech sounds choppy, like stuttering
• voice sounds strained or strangled

Abductor spasmodic dysphonia
• difficult to make sounds
• voice is weak, quiet
• voice sounds breathy or whispery

In both types, individuals have their normal voice when laughing, singing, reciting poetry, or in an exaggerated falsetto. The symptoms worsen with stress.

Diagnosis
There is no specific test for spasmodic dysphonia, so diagnosis is based on the voice symptoms and when other possible diagnoses (such as Parkinson’s disease) have been eliminated. Usually the affected individual is examined by a team of specialists, such as an ear, nose, and throat specialist (otolaryngologist), a specialist who treats speech and language disorders (speech-language pathologist), and a nervous system specialist (neurologist).

Treatment
There is no cure for spasmodic dysphonia, but treatments may help reduce its symptoms. Voice therapy may help. Injection of small amounts of botulinum toxin (Botox) directly into the affected muscles of the larynx generally improves the voice for three to four months. Multiple reinjections of Botox may be necessary to maintain a good speaking voice. There is also an operation that cuts one of the nerves to the larynx. This improves the voice for months to years but is also not a lasting solution. Even when the voice returns with treatment, it may be raspy, tinny, frail, or cracking.

Sources:
- The Associated Press, "'Dilbert' creator recovers from rare disorder." MSNBC.com 27 Oct 2006 09 Nov 2006 <http://www.msnbc.msn.com/id/15446515/>.
- "Spasmodic Dysphonia." Health Info. 01 Feb 2002. National Institute on Deafness and Other Communication Disorders (NIDCD). 09 Nov 2006 <http://www.nidcd.nih.gov/health/voice/spasdysp.asp>.
- "Spasmodic Dysphonia." Spasmodic Dysphonia FAQ. National Spasmodic Dysphonia Association. 09 Nov 2006 <http://www.dysphonia.org/faq.asp>.