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Spasmodic Dysphonia Part 2: Causes and Diagnosis

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This is the second post in a three-part series I'm writing about Spasmodic Dysphonia and the information offered at a recent symposium I attended at Nashville's Vanderbilt Voice Center. As in my last post, I would invite and appreciate any thoughts from other voice specialists and vocal coaches about your experience and opinions about this frustrating vocal condition. So how do you get spasmodic dysphonia? How is it even diagnosed? There are currently unsolved mysteries in the answers to both these questions. What Causes Spasmodic Dysphonia? Here's the current state of research: no one really knows for sure. Somehow improper and inappropriate signals are sent from the brain to the vocal cords that produce spasms of the muscles controlling the vocal cords. Estimates are that 5 in 100,000 people are affected, twice as many women as men. Onset usually presents in the mid 30's to 50's, but can begin in the teens. Sometimes the onset occurs after a viral illness or psychological trauma, sometimes after some kind of physical vocal damage. Sometimes, the person has been poisoned by taking a medication or being exposed to heavy metals. Sometimes there is family history of some kind of dystonia, or muscle spasm disorder. And sometimes, it seems to come out of thin air; someone just wakes up one day and the voice has a strange uncontrollable sound to it. And sometimes the voice is normal! What is known is that SD is exacerbated by stress, fatigue, pressure and tension. A speech language pathologist at the symposium explained it to me like this: the threshold for vocal dysfunction is much lower in SD patients, and the stress that can trigger a worsening of the symptoms can be mild. There is usually gradual onset, it gets worse, then levels off. How is Spasmodic Dysphonia Diagnosed? Many times the voice disorder called Spasmodic Dysphonia is ignored until it interferes with a person's lifestyle or employment. Often the first help sought will be from a vocal coach. That's a huge reason for all vocal coaches to be familiar with SD. The presenting symptoms occur with the speaking voice. If the speaking voice is fine, spasmodic dysphonia is extremely unlikely to be a problem, in fact all of my research into the disorder would lead me to dismiss the possibility outright, and suggest re-training the singing voice, which is likely to have problems with "muscle tension dysphonia" (MTD) instead. IMPORTANT: if vocal lessons and re-training does NOT result in quick progress, the presence of SD should be considered. Symptoms run the gamut:

  • You have trouble speaking, sounding chronically hoarse.
  • You are frequently asked if something's wrong with your voice.
  • Your speaking voice sounds tight, strained, strangled, breathy or whispery.
  • Spasms in your larynx often interrupt sound, causing words and sentences to be broken up.
  • However, breathing and swallowing feel normal.

Here is a video illustrating the sound of a voice plagued with variations of Spasmotic Dysphonia. Here are some audio file illustrations from a different source. Getting an accurate diagnosis of SD is difficult. It can take months or at least weeks to get a definitive diagnosis, because the symptoms of SD and MTD are very similar, and other vocal issues must be ruled out. Diagnosis is important, however, because treatment is different and must be tailored to the disorder.  What should you do if you suspect spasmodic dysphonia or any other voice disorder? If in doubt, get checked out by a medical team expertly familiar with SD such as the Vanderbilt Voice Center located in Nashville, Tenn. As vocal coaches, choir directors and drama teachers, if we suspect a physiological or neurological disorder like SD, we should always suggest a medical examination. At your check-up, you will have your vocal cords "scoped" to see if there are any physical problems that can be found in your larynx. You will be asked, probably by a speech-language pathologist (SLP) in the medical team to speak certain phrases such as:

  • "Aaron eats apples and oranges."
  • Help me hold this hoop, pet the pound puppy."
  • Sustain certain vowel sounds like "ee" and "ah", among other speaking and singing tasks.

But there is no brain scan or blood test for definitively identifying this disorder. The two evidences most relied upon for diagnosis of true spasmodic dysphonia are:

  1. The sound of the voice: vocal nuances can tell an experienced clinician with a good ear whether or not to suspect SD; and
  2. Whether or not a round of speech therapy and/or vocal training will work: the experts at the SD symposium suggest that if re-training offers limited or no success, the problem must originate in the wiring of the brain, possibly the basal ganglia, which cannot be re-trained.

I will discuss this theory as well as report on alternate theories in my next post about treatment options for SD patients. This essay first published July 9, 2009 on The Modern Vocalist.com the Internet's #1 community for vocal professionals, voice health practitioners and pro-audio companies worldwide since November 2008.


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