Muscle tension dysphonia (MTD) is a condition of hoarseness or other symptoms related to voice production, which occurs as a result of inappropriate use of the muscles around the larynx during speech or singing. MTD may occur on its own, called primary MTD - or as a result of another underlying disorder, called secondary MTD. The cause of primary MTD is often unclear. It may be triggered by illness, allergies, reflux, other irritants, or by increased vocal demand. In some instances, the cause may be related to underlying stress and anxiety or a significant emotional event. In secondary MTD, the voice is produced with excessive muscle tension as a means of compensating for an underlying problem, such as nodules, a polyp, or vocal fold paresis.
MTD may result in a variety of symptoms, including altered voice quality, but also effortful voice production, easy fatigue when using the voice, and soreness, tightness or general discomfort in the neck or throat. Changes in the quality of the voice range from breathy to strained to rough or raspy. Some individuals are unable to produce voice at all, a condition called “aphonia.” Symptoms typically increase in proportion to voice use.
MTD may be diagnosed by history and the clinical appearance of the larynx. Voice change or generalized discomfort, which appears and/or worsens with voice use, is a highly suggestive feature of the history. Tenderness to touch of the muscles surrounding the larynx, and narrowing of the soft tissue space between the thyroid cartilage and the hyoid bone, also suggest excessive muscle tension. During laryngoscopy, we can see that the structures above the vocal folds are typically not involved in voicing. In muscle tension dysphonia, there is often evidence of muscle activity in these areas, known as “supraglottic hyperfunction” or, more colloquially, “squeeze".
MTD is multi-faceted, and may explain many phenomena in the larynx. This creates two difficulties. First, it is tempting to use MTD as an explanation in puzzling cases. It is important not to make the diagnosis hastily, as it makes underlying problems easy to overlook. Second, it is often not possible to make the diagnosis definitively, so voice therapy is sometimes used as a trial treatment, with relief of symptoms validating the diagnosis, and lack of response triggering a re-evaluation.
Behavioral treatment in the form of voice therapy is generally recommended for treatment of MTD. The specific therapy plan and other recommendations depend upon whether the MTD is primary or secondary in nature.
Treatment of primary MTD involves identifying triggers of the problematic vocal behaviors - be they related to medical conditions, emotional situations, or vocal habits - and working on managing these triggers without affecting voice production. Voice therapy can help to establish healthy vocal patterns without inappropriate muscle involvement. It may be beneficial for the patient with primary MTD to be referred to other specialists to help address some of these triggers. Recovery times may vary, from one to several voice therapy sessions.
Treatment of secondary MTD involves addressing both the MTD and the underlying condition. Even if the underlying condition is addressed, MTD may not spontaneously resolve. Voice therapy may be necessary for treating muscle tension that has become a habit. An analogy can be found in how one might compensate for an ankle injury by adjusting posture to place less weight on the injured ankle. An injury to the vocal folds can cause one to produce the voice in an unhealthy way as a means of compensating for the injury. Sometimes, the compensatory habit remains even after the injury has been “healed.”