Understanding the Disorder
Muscle Tension Dysphonia (MTD)
The term “muscle tension dysphonia” is a general term for an imbalance in the coordination of the muscles and breathing patterns needed to create voice. This imbalance can be seen without any anatomical abnormality (primary MTD) or in the presence of an anatomical abnormality (secondary MTD). In the case of secondary MTD, the muscle tension is thought to be the body’s natural compensatory process to adjust for the vocal injury. This section will discuss primary MTD.
Stress and Anxiety
Primary MTD can be associated with stress and anxiety. Recent research has shown that under periods of stress, the muscles that control the voice box become tense. Periods of prolonged muscle tension in the voice box can lead to an incoordination of the vocal control system.
Primary MTD often occurs following an upper respiratory illness, such the cold or flu. In the case of an upper respiratory tract infection, the muscular imbalance is not thought to be connected to stress and anxiety. Significant stressful life events, such as the loss of a loved one, can cause muscle tension dysphonia as well.
Muscle tension dysphonia is a highly variable condition. The most common symptom of primary MTD is a change in voice quality, ranging from mild to severe and it is often associated with pain or discomfort while speaking. The voice can be affected during speaking, singing or both. Often, hoarseness will be associated with an increased effort to talk and subsequent fatigue or tiring of the voice with continued use.
Common Symptoms Associated with MTD
- Vocal fatigue
- Unreliable voice
- Low, gravely voice
- Voice breaks
- Airy or breathy voice
- Inability to sing
- Hoarse and rough quality
- Extra force needed for loud voice
- Vocal symptoms worsen with stress
- Inconsistent voice
- Voice sometimes returns to normal
How is the diagnosis of MTD made?
1. Patient History: A history of how the voice problem started and an evaluation of voice and speaking behaviors are important steps in the diagnosis of primary MTD.
2. Speech-Language Pathology Evaluation
- Examination by a speech-language pathologist is very important in the diagnosis of muscle tension dysphonia.
- Improvement in voice through trial voice therapy techniques is key to determining that the vocal disorder is due to a muscular imbalance.
- Acoustic and aerodynamic measurements are also valuable assessment tools to determine normal voice and breathing behaviors.
3. Laryngoscopy and Stroboscopy
- Careful examination of the vocal folds is essential for making the diagnosis of primary MTD. It is a diagnosis of exclusion; therefore, careful examination of the vocal folds is necessary to rule out anatomical abnormalities.
- Flexible laryngoscopy allows the clinicians to observe some muscular patterns during speaking.
- Stroboscopy allows the examiner to assess the mucosal wave as a marker for vocal fold vibration.
4. Investigation for Other Associated Abnormalities
- The diagnostic process should also focus on looking for important associated factors, such as:
- Side effects of medications (e.g., diuretics and antihistamines)
- Hormonal Imbalance
Voice therapy is the gold standard treatment for primary MTD. There are no other treatments that can restore the muscle balance in the vocal mechanism. Voice therapy helps the patient improve vocal symptoms through exercises and techniques geared at improving the way the body (muscles, lungs etc.) work together to create voice.
In cases of primary MTD associated with stress or anxiety, it can be very helpful for the patient to work with a counselor to reduce stress in addition to completing voice therapy.