The Impact of Vocal Fold Paralysis On Voice
Vocal fold paralysis is due to a total interruption of nerve inputs to the voice box muscles or laryngeal muscles resulting in a total loss of laryngeal muscle movement. This affects the coordinated muscle contractions needed for voice production.
Importance of Vocal Folds In Voice Production
Inability of the paralyzed vocal fold to open results in poor glottal opening which leads to breathing problems, which can be life threatening, and interferes with voice production. For normal speaking and singing, both vocal folds need to be aligned in the midline "closed". In this position, the air pressure from the lungs passes through the vocal folds making them vibrate. When vocal folds are not aligned in the midline, vocal vibration is hampered–hence the voice disorder.
Who Does Vocal Fold Paralysis Affect?
Vocal fold paralysis has no particular age or gender susceptibility. It can happen to anyone for a variety of causes, and the impact varies according to a person’s voice demands. Each case is unique due to many factors including:
· the degrees of weakness of the voice box muscles
· adaptability of the other laryngeal muscles
· variety of patient needs affected by gender, age, as well as overall health.
Common Patient Complaints
Although no two cases are alike, and patient complaints vary, symptoms of vocal fold paralysis may include of one or more of the following:
· hoarseness–croaky or rough voice
· breathy voice–a lot of air with the voice, voice sounds like whispering
· effortful phonation–extra effort on speaking
· air wasting- needs lots of air pressure to produce usual conversational voice,
such that patient “runs out of air” when speaking
· diplophonia sounds like a "gargle voice"
Unilateral and Bilateral
The location, nerve(s) affected and the residual (remaining) strength or tone of the affected vocal fold(s) determine the type of paralysis and the resulting voice quality. Vocal fold paralysis may be unilateral (only one side is paralyzed) or bilateral (involving both sides).
When unilateral vocal fold paralysis occurs, patients present with vocal symptoms ranging from mild to severe dysphonia. The perceptual symptoms of unilateral vocal fold paralysis are characterized by breathiness, low intensity, low pitch and intermittent diplophonia (simultaneous production of two pitches). Patients with this pathology often experience physical fatigue resulting from increased effort used to produce voice and the breathiness associated with phonation. Unilateral vocal paralysis is a common cause of neurogenic hoarseness. Some patients do not notice any significant functional limitation related to their unilateral vocal fold paralysis. Unilateral vocal fold paralysis is pictured below.
Normal speaking voice is typically restored in patients that present with this paralysis when properly evaluated and treated.
Bilateral vocal fold paralysis, although rare, is the most serious form of vocal fold paralysis. When this pathology occurs, and both vocal cords are paralyzed in the midline position (known as bilateral abductor paralysis), they are unable to open to allow sufficient airflow
for vocal fold vibratory behaviors. In this severe case, surgical placement of a tracheostomy is needed to establish an adequate airway. When bilateral vocal fold paralysis occurs with both vocal cords positioned in an open position (bilateral adductor paralysis), voice
production can not be satisfactorily achieved. Patients with this pathology often require augmentative communication aids, due to the complete aphonia (loss of voice). Bilateral Vocal Fold Paralysis is pictured below.
Many cases of vocal cord paralysis will recover within several months.
In some cases however, the paralysis will be permanent, and may require active treatment to improve the voice.
This patient has a left vocal cord paralysis that results from a lung cancer. In this case the recurrent laryngeal nerve that is responsible for vocal cord movement is affected by the cancer