Laryngeal Muscle Tension Disorders: Breathing Manifestations
"Laryngeal muscle tension disorder" is the general term given to describe a variety of conditions that can cause both voice and breathing problems. Breathing manifestations of muscle tension disorders can produce severe airway obstruction as well as a hoarse voice. This disorder goes under a variety of names, including inspiratory adduction (IA), paradoxical vocal fold movement, laryngeal dystonia, and paroxysmal laryngospasm. This page provides more information on how laryngeal muscle tension disorders can affect breathing. A second page describes the way in which laryngeal muscle tension disorders can affect the voice.
Movements of the vocal folds during breathing are described in more detail in the page on anatomy of the larynx. Briefly, when we breathe the vocal folds are opened ("abducted") by a pair of muscles called the posterior cricoarytenoids. Air can then easily pass through the vocal folds into the lungs.
With a severe laryngeal muscle tension disorder, the vocal folds will be inappropriately closed ("adducted") during inspiration, producing airway obstruction. The term inspiratory adduction therefore most appropriately describes the mechanics of this disorder.
What are the symptoms of inspiratory adduction (IA)?
IA can present with symptoms of severe airway obstruction and feelings of suffocation. It obviously is a very frightening situation and frequently results in a trip to the emergency room. More mild cases can produce noisy breathing ("stridor") with less pronounced shortness of breath. The symptoms are very similar to asthma and distinguishing the two can be difficult. The situation is also complicated because there seems to be a tendency for IA to develop in individuals with asthma. However, in IA there is typically not the chest wheezing one hears in asthma, and the symptoms do not improve with standard asthma medications.
It is important to distinguish IA from bilateral vocal fold immobility. In bilateral vocal fold immobility, the folds cannot physically move. This may be due to bilateral injury to the nerve supply to the larynx, or there may be scarring of the joint that moves the vocal folds. The key difference is that in IA the folds can potentially move normally, and in bilateral vocal fold immobility they are fixed in one position.
If the patient is symptomatic during the examination, the diagnosis is easy to make. Using a flexible fiberoptic scope, the vocal folds will be seen to come together during inspiration. The symptoms are often present only with voluntary inspiration, that is, when the patient is asked to take a deep breath. During quiet involuntary inspiration the folds often behave normally.
The pictures above show this behavior. The top photo to the left shows a patient taking a normal deep breath; in this case the breath occurred between words while she was speaking. The white bands in a "v" shape are the vocal folds; note that they are widely opened with a good view into the windpipe (trachea).
The photo to the right shows the position of the folds when this same patient was asked to take a deep breath. Note that the whole larynx is compressed and the vocal folds are hardly open. In this position there will be more resistance of air flow into the lungs.
One of the problems with diagnosing IA is that it often is episodic and the patient may be totally asymptomatic during the time of the exam. Unfortunately, the severe episodes often have ended by the time a physician can perform a fiberoptic exam.
What causes inspiratory adduction?
The causes of IA are highly variable and, quite frankly, still unknown. It is known that reflux of gastric contents onto the larynx (also called Laryngeal Pharyngeal Reflux Disease, or LPRD for short) can cause the vocal folds to spasm shut. Some individuals with LPRD at nighttime will awaken with an a choking sensation. On examination, many individuals with IA will have signs and symptoms of reflux disease, including swelling and irritation of the back of the larynx. With chronic inflammation, the vocal folds may be much more susceptible to spasming shut ("laryngospasm").
As mentioned above, IA seems to be more prevalent in individuals with asthma. One theory is that attempts to improve breathing during asthma attacks includes some form of inspiratory adduction. Over time, this breathing pattern may persist even in non-asthmatic situations
As with voice disorders from MTD, stress plays an important role in causing IA. Almost everybody has experienced a tightening in the throat during stressful situations. In some individuals this response may become extreme, leading to actual breathing problems. Since shortness of breath itself produces anxiety, the condition can deteriorate even more as the patient has more respiratory distress.
How is inspiratory adduction treated?
It is important to first confirm the diagnosis, and as noted above this can be difficult to accomplish. It is important to make sure the airway difficulty is not due to a lung problem, to blockage of the airway by some other mass, or bilateral vocal fold immobility.
Since the symptoms appear to be worsened by reflux disease and asthma, these conditions should be treated to the maximum. In some cases, a combination of lifestyle changes and antireflux medications can reduce back the inflammation on the larynx and significantly reduce the breathing symptoms.
Once these measures have been done, the mainstay treatment for IA is speech and voice therapy geared towards learning laryngeal and neck relaxation techniques. If stress or anxiety is present (it often is), psychological counseling may be useful. All of these treatment modalities are focused towards learning techniques to prevent attacks by reducing the muscle tension in the neck and to break out of laryngospasm once it has occurred.
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