Can it be...MTD? Muscle Tension Dysphonia Defined.

Completely over diagnosed. Wrongly diagnosed. Underdiagnosed. What the heck is MTD?

Muscle Tension Dysphonia is a term that describes a certain type of voice problem or voice disruption with massive underlying tension, and no other pathological cause. So you have an odd vocal quality or hoarseness, and you are as wound up as Lindsay Lohan's newest attorney. This tension can be found in the upper body area, like the shoulders, neck, jaw, base of tongue and the larynx. The tension can be painful, and many times there are concomitant conditions like stress and emotional conflict making the symptoms worse. There are 2 types of muscle tension dysphonia according to Clinical Voice Pathology by Stemple et al, and 3 according to the voice doctor, Dr. James Thomas.

Do you see cases of MTD in your practice? MTD can often be confused with Spasmodic Dysphonia, so it is important to correctly identify each. I see a lot of vocal hyperfunction, and it's a mix on the cause. Most of the time it is easy to see that there is overcompensation for lack of true vocal fold mass, movement, etc. You must make sure you are taking into consideration the type of examination when making a diagnosis. No one likes a rigid scope in the mouth, so some laryngeal tension could be caused from the exam itself. 

Three Types of MTD:

  1. Primary MTD (Non-organic hyperfunction)
  2. Primary MTD (muscle tension gap)
  3. Secondary MTD (hyperfunction in presence of vocal disturbance)

Stemple and colleagues describe Primary MTD as excessive tension affecting the voice with no other cause. Dr. Thomas agrees, and elaborates on two different types of Primary MTD. He divides the primary category into two: Non organic dysphonia/hyperfunction and muscle tension gap. Primary MTD can present as hyperfunction on a videostroboscopy examination with complete closure of the true vocal folds, however there is some type of superior constriction present. That means that you will see anterior-posterior or medial compression above the true vocal folds. The false vocal folds may be squeezing together so tightly that your view of the true folds is almost completely obscured. This might make it hard to see if there is underlying weakness. This type of patient may have developed this excessive hyperfunction gradually and now it has become the new normal for making sound. Voice therapy can ease the tension with upper body relaxation stretches, circumlaryngeal massage and tension-free phonation training.

Muscle tension gap is different, Thomas argues. He states that the vocal folds can remain open secondary to abductor and adductor muscles simultaneously contracting during phonation. Like the non-organic MTD, this can be learned and compensatory. It could be a muscular habit that will not die, like if vocal nodules are removed. Vocal nodules can be improved and eradicated usually by voice therapy alone, but some surgeons still operate. The patient has learned the way to make sound with the nodules present, a little like playing football with a poorly inflated football. (You can do it successfully after a learning curve, but it's probably going to cause some trouble. Sorry Tom Brady.) An hourglass vocal fold closure is all that can be achieved. The adductor muscles only have to bring the vocal folds together to a certain degree before the nodules prohibit any further contact with the remaining free edges of the folds. Fast forward to the nodules being suddenly removed by a surgeon, the muscles may maintain that same pattern, and only come together so closely. Voice therapy can teach the patient how to phonate completely (and achieve that full closure again) by teaching new motor patterns.

Secondary MTD involves a pathology of some kind like paralysis or lesions, where the patient is overcompensating for the deficit. Secondary MTD is dubbed hyperfunction representing hypofunction by Thomas. With a pathology present, the patient is utilizing hyperfunction to compensate for lack of true vocal fold use. You need to look beyond the superior constriction here to notice why the patient is squeezing. Is there a paralyzed vocal fold? Is there bilateral atrophy and bowing? Is there a polyp? Is there recurrent laryngeal nerve damage? Voice therapy can be beneficial here, but it would be best to address the underlying issue first. If it is atrophy, the patient's ENT might consider implants or injectables. If it is paralysis, the ENT might recommend waiting about 9 months to see if it is true paralysis before laryngoplasty.

Dr. Thomas has this nice educational video to aid in any persisting confusion.

So when you see a patient with laryngeal hyperfunction, make sure you are determining what is causing the hyperfunction. If you're coming up empty handed (not to be confused with a deflated football in hand), perhaps it is true MTD.

-ATVC

 

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