Normal voice production depends on power and airflow supplied by the respiratory system; laryngeal muscle strength, balance, coordination, and stamina; and coordination among these and the supraglottic resonatory structures (pharynx, oral cavity, nasal cavity).
A disturbance in one of the three subsystems of voice production (i.e., respiratory, laryngeal, and subglottal vocal tract) or in the physiological balance among the systems may lead to a voice disturbance. Disruptions can be due to organic, functional, and/or psychogenic causes.
Organic causes include the following:
- Vocal fold abnormalities (e.g., vocal nodules, edema, glottal stenosis, recurrent respiratory papilloma, sarcopenia [muscle atrophy associated with aging])
- Inflammation of the larynx (e.g., arthritis of the cricoarytenoid or cricothyroid, laryngitis, laryngopharyngeal reflux)
- Trauma to the larynx (e.g., from intubation, chemical exposure, or external trauma)
- Recurrent laryngeal nerve paralysis
- Adductor/abductor spasmodic dysphonia
- Parkinson's disease
- Multiple sclerosis
Functional causes include the following:
- Phonotrauma (e.g., yelling, screaming, excessive throat-clearing)
- Muscle tension dysphonia
- Ventricular phonation
- Vocal fatigue (e.g., due to effort or overuse)
Psychogenic causes include the following:
- Chronic stress disorders
- Conversion reaction (e.g., conversion aphonia and dysphonia)
The complementary relationships among these organic, functional, and psychogenic influences ensure that many voice disorders will have contributions from more than one etiologic factor (Stemple, Roy, & Klaben, 2014; Verdolini, Rosen, & Branski, 2006).
Recognizing associations among these factors, along with patient history, may help in identifying the possible causes of the voice disorder. Even when an obvious cause is identified and treated, the voice problem may persist. For example, an upper respiratory infection could be the cause of the dysphonia, but poor or inefficient compensatory techniques may cause dysphonia to persist, even when the infection has been successfully treated.