A common cause of voice problems is abnormal patterns of muscle activation, as seen in Spasmodic Dysphonia and VCD. Here is another Vocal mysterious disease referred to by many names, including muscle misuse dysphonia, vocal hyperfunction, or muscle tension dysphonia (MTD).
The balance of aerodynamic and muscle forces in voice production must adapt to rapidly changing speech requirements, including modulations of pitch, loudness, and rate, which are a component of all speech contexts.
When an imbalance of muscle activity occurs during phonation, the result can be a range of symptoms from vocal fatigue, neck discomfort, altered vocal quality, to complete loss of voice.
There are many theories about the nature and causes of MTD, but little is known for certain, and MTD may vary among individuals. One theory is that the underlying mechanism of MTD is an incomplete relaxation of the posterior cricoarytenoid muscle, the muscle responsible for opening the vocal folds. This may result in the incomplete opening of the vocal folds during each vibratory cycle of phonation, which in turn causes the thyroarytenoid muscle (the body of the vocal folds) to over-contract in compensation.
Other theories describe the nature of MTD as an excessive contraction of groups of intrinsic laryngeal muscles (the muscles of the vocal folds and those that connect the vocal folds and cartilages) and extrinsic laryngeal muscles (the muscles that connect parts of the larynx to other structures).
Still, another theory describes MTD as in-coordination of laryngeal muscle contraction with breathing, especially the amount of air pressure and the timing of the airflow.
It is unclear whether MTD represents a disorder primarily of poor coordination (mis-timing) of muscles or excessive muscle contraction. In either case, it can result in impaired vocal fold vibration and the sensation of extra effort when talking.
The cause of muscle tension dysphonia is not known. We hypothesize that it may be caused by the body’s voice production system reacting to environmental (external) or systemic (internal) irritants. Common irritants include upper respiratory infection, second-hand smoke, GERD, significant vocal demands, or stressful life events. Most often, it is likely more than one single factor. But truthfully, we do not yet understand why some people are susceptible to MTD and others are not.
MTD – Muscle Tension Dysphonia
Historically, MTD was called “functional” dysphonia, because the cause was unknown. However, that term often implied that there was no “real” reason for the problem and it was assumed to be a psychosomatic disorder. Although psychological factors may certainly contribute to MTD, Researchers no longer feel it is primarily a psychosomatic problem.
The most common treatment for MTD is Voice Therapy Where abdominal breath support and vocal projection and vocal cords physiotherapy are the main three pillars of therapy.
My clinical experience suggests that voice therapy is quite helpful, even in severe cases in which a person has almost no voice at all. Uncommonly, The ENT surgeon can use Botulinum toxin A (“botox”) injections in conjunction with voice therapy. To release the abnormal muscle activation patterns. Just like on Spasmodic Dysphonia cases.
M.Sc. CCC-SLP for AmplioSpeech