SD -vs- MTD

With MTD you really need to "unlearn" inappropriate vocal habits you have slipped into - and the standard treatment is to work on this with a speech pathologist.

Both produce a squeezed effortful voice, and it is not easy to distinguish between the two.

I've grossly over-simplified this, as you asked for a "simple" explanation. For a fuller explanation I would recommend these links:

http://www.voice-center.com/MTDvoice.html

http://www.bgsm.edu/voice/overview_sd.html

This is what the NSDA's website says about MTD:

Is SD the same as Muscle Tension Dysphonia (MTD)?
Muscle Tension Dysphonia is a type of voice disorder that often "masquerades" as SD and many such people are misdiagnosed with it. MTD involves a consistent tightening of the laryngeal muscles and is often called Hypertensive Dysphonia. This problem responds very well to vocal rehabilitation. In very severe cases, when vocal therapy does not help, botulinum toxin injections can be tried to help relieve symptoms.

Thanks for the clearist answer I've heard regarding SD vs MTD. For years I went to specialist after specialist and a speech therapist who did not clearly explain the difference nor did they care to reconize the difference.

I now know my SD had to have started out with MTD then lead too Spasmodic Dysphonia. Bet you didn't know you would make a good doc. LOL

To the best of my knowledge MTD (a functional, not organic, disorder where the patient has developed inappropriate voicing habits, for whatever reason) does not lead to, or cause, SD, which is a neurological movement disorder - the voice that results from laryngeal dystonia.

David Barton (AD/SD, New Zealand)

I am trying to clarify here. Are you saying that there is no way I could have had MTD which lead to SD? If so why would the surgery have been so sucessful for me, if I did not have SD? And why would Botox inections not work at times for me? I am not sure I understand exactly what it is that you are saying here.

Please don't take my comments as expert medical opinion. What I post here is only based on extensive reading and synthesised from presentations I have heard at NSDA symposiums etc. I'd rather comment in general terms than about your particular case.

MTD, in my opinion, can be corrected by the patient changing their voicing methods, with expert guidance of course. How MTD arises is unknown, and I won't speculate on that. I would say though that an MTD patient would be highly unlikely to speak that way on purpose - so it's misuse, rather than abuse of the vocal apparatus.

Laryngeal dystonia (this is the disorder that causes the voice we describe as spasmodic dysphonia), in contrast, is a neurological movement disorder and is certainly not caused by vocal abuse/misuse. So there is no reason why MTD (a functional vocal disorder) would trigger SD, which is really the brain delivering the wrong signals to your vocal cords. An SD patient can't blame vocal abuse/misuse for their voice problem.

Remember that SD is often misdiagnosed as MTD in the first place. It's much more likely (almost certain in my opinion) that a patient who has been diagnosed with MTD and then, correctly, told they have SD, has been misdiagnosed in the first place rather than both diagnoses being correct.

The SLAD-R surgery, to the best of my knowledge, is directed at people who have a firm diagnosis of ADductor SD. It's almost certainly an inappropriate treatment for MTD, which usually responds to voice therapy.

There are a number of reasons why Botox injections don't work sometimes or stop working - these are not really related to whether a diagnosis of SD is correct.

I too think that if it wasn't SD, that the speech therapy and botox injections would have worked. Anyway, I appreciate your comments.