Muscle tension dysphonia (MTD)

A common cause of voice problems due to abnormal patterns of muscle activation.

Voice production requires rapid and precise coordination of many muscles.

The degree of muscle contraction, the timing of the contraction and its coordination with the simultaneous contraction of many other muscles, must be balanced with changing airflows and air pressures.

Aerodynamic and muscle forces must adapt to changing speech requirements, including modulations of pitch, loudness, and rate, that are a component of all speech contexts.

Imbalance of muscle activity during phonation, can result in a range of symptoms from vocal fatigue, neck discomfort, altered vocal quality, to complete loss of voice.

Incomplete relaxation of the posterior cricoarytenoid muscle, which is responsible for opening the vocal folds, may result in incomplete opening of the vocal folds during each vibratory cycle of phonation, which in turn causes the thyroarytenoid muscle to over-contract in compensation.

May be an excessive contraction of groups of intrinsic laryngeal muscles and extrinsic laryngeal muscles.

It is also suggested to be an in-coordination of laryngeal muscle contraction with breathing, especially the amount of air pressure and the timing of the airflow.

The process results in impaired vocal fold vibration and the sensation of extra effort when talking.

The vocal tract above the true vocal folds in constricted, making it difficult to produce voice.

Cause of muscle tension dysphonia is unknown.

It may be caused by the body’s reaction to environmental or systemic irritants.

Common irritants include upper respiratory infection, second-hand smoke, laryngopharyngeal reflux, significant vocal demands, or stressful life events.

It is likely more than one single factor plays a role.

In primary MTD, there is no clear or predominant organic cause, and was called “functional” dysphonia

In some cases of primary MTD, the precipitating cause is no longer present, but the aberrant muscle behaviors have become a habit.

In an attempt to compensate for vocal changes, individuals alter muscle activation patterns, possibly by using excessive muscle tension or recruiting the use of muscle not ordinarily active: referred to as “maladaptive compensatory behaviors”.

Maladaptive compensatory behaviors can become a habit over time.

In either primary or secondary MTD, the habitual use of abnormal patterns of muscle activation during phonation In either primary or secondary MTD, can be difficult to treat.

The most common treatment for MTD is voice therapy, including resonant voice techniques and digital laryngeal massage.

Uncommonly, Botulinum toxin A injections are used in conjunction with voice therapy. to release the abnormal muscle activation patterns.

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