It can be confusing to get a diagnosis of muscle tension dysphonia on top of something like spasmodic dysphonia. Let's break this down.
What is Muscle Tension Dysphonia?
Muscle tension dysphonia, or MTD, is a hyperfunctional voice disorder that is caused by excessive tightening or squeezing of the muscles in and around the larynx during speech. The excessive muscle use and strain during speaking prevents efficient phonation and causes a strained vocal quality. It is believed that there are two types of MTD: Primary MTD and Secondary MTD. Primary MTD develops in the absence of any structural or physiological abnormality in the larynx. Secondary MTD, on the other hand, develops as a compensatory method for speaking with a voice pathology/voice disorder or any other disease that may affect normal phonation patterns. For example, secondary MTD can develop secondary to spasmodic dysphonia, tremor, vocal fold atrophy or paralysis, vocal fold lesions, laryngopharyngeal reflux and more. In both cases, the muscles in and around the larynx are uncoordinated and get into a pattern of excessive force to get voice out.
Symptoms of MTD
Individuals with MTD may experience symptoms of both change in quality of the voice but also experience symptoms of how speaking feels. He/she may notice increased hoarseness or a strained quality to the voice. Some may experience breathiness and some with more severe MTD may note periods of strain but where the voice will fail to come out at all (called aphonia). MTD can present with voice breaks or cuts off in sounds if the tension in and around the voice box is severe. One may also note soreness in the throat muscles during or after speaking, or vocal fatigue at the ends of days or after speaking for longer. There may other “throat” symptoms related to these increased sensations including the feeling of mucus or something present in the throat, frequent need to throat clear, frequent discomfort in the throat, or sometimes even difficulty swallowing solid foods and/or discomfort with swallowing. Some with severe MTD may also experience tightness in muscle groups surrounding the larynx like the neck, shoulders, upper body and jaw as he/she works harder to produce voice. Individuals may feel more tenderness, discomfort or pain upon palpation of the neck muscles and spaces between laryngeal cartilages. Symptoms for most with MTD will typically worsen with more voice use or continuous speaking.
Characteristics of MTD
MTD is more prevalent among women than men. Some research suggests that individuals with high levels of stress, certain personality types, or those who have high vocal demands may be more likely to develop MTD. The symptoms of MTD tend to be consistent across speech contexts and are not sound specific (this is unlike spasmodic dysphonia).
What is the cause of muscle tension dysphonia?
There are many potential causes for the development of MTD. Secondary MTD often develops as a method of compensating for another voice disorder or disorder that makes it harder to voice in a normal manner. The muscles of the larynx begin to engage too much, in attempts to either make the voice sound normal again, or to get a more consistent or more functional voice to meet one’s speaking demands that are now more challenging given the underlying voice disorder. Primary MTD can develop after an illness like an upper respiratory infection, or acute laryngitis, as your body gets used to pushing to make a voice during an acute illness. This pattern of excessive muscle strain may not go away on its own, even after the illness or virus goes away, resulting in MTD that remains despite the lack of an underlying disorder any longer. Primary MTD can also be caused by significant ongoing stress.
Diagnostic Tools
Muscle tension dysphonia can best be detected in connected speech. A full diagnostic assessment is usually completed by both a speech language pathologist and otolaryngologist. You may be asked to read sentences that will collect acoustic measures, qualitative voice evaluations, and aerodynamic measures. You may also be asked to complete tasks to help to differentially diagnose muscle tension dysphonia versus other similarly presenting disorders, like spasmodic dysphonia. The treating otolaryngologist or speech language pathologist will likely palpate the muscles in your neck to feel for any tension in the muscles surrounding the larynx or in the upper body region. He/she may determine if a trial of laryngeal massage results in decreased strain or increased vocal quality.
Flexible or rigid laryngoscopy with videostroboscopy should be performed to look at the anatomy of the larynx and vibration of the vocal folds during speech. In individuals with MTD the muscles around the vocal folds often can be seen compressing or “squeezing” during phonation during laryngoscopy.
It may be difficult to get an accurate diagnosis for MTD because MTD can co-occur as a secondary or compensatory response to an underlying voice disorder. The MTD symptoms or excessive muscle tension may sometimes mask symptoms of the underlying or primary disorder. Sometimes, once the overlying muscle tension is reduced, symptoms of the underlying voice disorder may emerge or may become more apparent.
Voice therapy “stimulability” will be conducted by a speech language pathologist to determine if the patient would benefit from voice therapy, based on the patient’s response to voice therapy probes. A “trial” of voice therapy may be conducted to help differentially diagnose between MTD and spasmodic dysphonia. If the patient has resolution of symptoms within the first several sessions the diagnosis is clarified as MTD. If the patient does not make quick, easy or steady progress with therapy the patient likely has another disorder that presents similarly to MTD (i.e. spasmodic dysphonia) or secondary MTD masking another primary voice disorder.
Treatment Options
Voice therapy is the standard treatment for muscle tension dysphonia. Individuals are taught ways to speak with less effort and with decreased muscle tension. Muscles are taught to relax during speech, rather than strain. Individuals may be given techniques to increase more efficient coordination of the speech subsystems and the muscles involved in voice production. Some examples are getting a patient to more efficiently use airflow, using laryngeal massage to manually release tension in the larynx and neck, and using resonant voice techniques to increase accurate voice placement and efficient phonation patterns. Generally only a few voice therapy sessions will be needed to retrain muscles to reduce MTD. If an individual has MTD secondary to another voice disorder the primary voice disorder will be targeted through a comprehensive treatment plan with a speech language pathologist along with an otolaryngologist. Sometimes treatment of the underlying voice problem is enough to eliminate secondary MTD. However, sometimes the MTD will remain despite resolution of the primary voice problem. If this is the case, voice therapy will target the remaining MTD symptoms.