There are many theories about the nature and causes of MTD, but little is known for certain. It may be caused by the body’s voice production system reacting to environmental (external) or systemic (internal) irritants, including upper respiratory infection, second-hand smoke, laryngopharyngeal reflux (LPR), significant vocal demands, or stressful life events. Most often, it is likely more than one single factor.
MTD is sometimes categorized as either primary—with no clear or predominant organic cause—or secondary, where the abnormal patterns of muscle activation are a result of another underlying disorder, such as vocal fold atrophy or a benign lesion. When an imbalance of muscle activity occurs during phonation, the result can be a range of symptoms, including vocal fatigue, neck discomfort, altered vocal quality, and/or complete loss of voice.
The most common treatment for MTD is voice therapy. There are a number of different therapeutic regimens that improve voice production, including resonant voice techniques and digital laryngeal massage.