Muscle tension dysphonia

Pathophysiology The pathophysiology of MTD is multifactorial. Voice production requires the coordination of multiple muscles and other structures in the larynx. It is caused by increased tension of the laryngeal muscles secondary to personality traits such as anxiety or life factors such as increased stress. Secondary MTD Secondary MTD is caused by an underlying medical or physical reason. Vocal fold lesions such as a vocal fold nodule or other changes in the vocal fold mucosa can lead to increased tension in the larynx and cause dysphonia. Larynogopharyngeal reflux, a process that is similar to GERD, can bring stomach acid into the larynx. This can provoke the larynx to tense to prevent the aspiration of the acid. It also has been found that MTD can occur in postmenopausal women due to decreased hormone levels which lead to swelling of the laryngeal tissues and eventual atrophy. Older men can also develop MTD as their vocal cords thin as they age. Post infectious MTD is also possible. For example during an episode of laryngitis, the muscles of the larynx tense secondary to the inflammation and residual tension can remain following the resolution of the illness. == Signs and symptoms ==

The voice quality in MTD can be described as breathy and can also sound harsh. Patients may complain that their voice sounds abnormal as well as needing to strain to produce sound, and having increased dysphonia with increased vocalization. == Diagnosis ==

A multidisciplinary team including otolaryngologists and speech language pathologists is useful for the evaluation and diagnosis of MTD. Voice quality The voice in MTD has been described as hoarse and breathy. In MTD, all vocal tasks (vowels, singing, etc) are difficult for the patient while in adductor spasmodic dysphonia, some vocal tasks are difficult while others are unaffected. This index is made up of many measurements of the voice include voice frequency measurements (high and low), maximum phonation time (MPT), and jitter (frequency instability). Vocal fold visualization Videostroboscopy is the use of a camera to see the larynx and vocal cords. Stroboscopy allows the visualization of vocal cord movement, which vibrate too quickly for human eye to perceive. sEMG can measure the muscle units of the muscles of the larynx to deduce if there is increased activity which means they are more tense. while others do not demonstrate a difference in EMG between individuals with MTD and individuals without MTD. == Treatment ==

Medical treatment In secondary MTD, the underlying medical cause should be addressed. Residual infections should be treated. The goal of voice therapy is to encourage proper vocal use and decrease the tension of the laryngeal muscles. Examples of voice therapy include voice exercises to help increase glottic closure, vocal hygiene, manual laryngeal therapy, respiratory exercises, nasal exercises and frequency modulation amongst other techniques. Manual therapy Manual therapies include the physical manipulation of the larynx, hyoid bone, thyroid cartilage, neck (sternocleidomastoid) muscles, and cricothyroid visor. The various applications of pressure, rotational massage, circular compression, kneading, and stretching increase range of motion and muscle efficiency while decreasing stiffness, tenderness, muscle tension, and muscle contraction. The larynx is lowered and moved side to side in manual circumlaryngeal therapy (MCT). The patient is able to track changes in vocal quality by humming or vocalizing during the process. Patients with MTD have shown long term improvement after treatment with MCT, Mathieson laryngeal manual therapy (MLMT), and the cricothyroid visor maneuver (CVM). Paired with abdominal breath support, MCT has improved voice quality in patients with MTD as measured by the DSI. One study found greater improvement in the physical components of the Voice Handicap Index (VHI) for patients with MTD after treatment with MCT versus a greater improvement in voice quality as measured by the DSI using vocal facilitating techniques. Another study found vocal therapy had a greater impact on VHI scores than physical therapy for patients with MTD. It is suggested that patient symptoms determine the appropriate use of voice therapies and manual therapies. Surgery Surgery may be used as a treatment when there is a vocal lesion such as nodule or polyp that is causing the MTD. There is little utility to surgery in primary MTD. == References ==