When the voice box muscles stop receiving nerve input from the vocal cords, a full or partial paralysis may have occurred. A total interruption of the nerve impulse is known as paralysis, and results in no movement of the vocal cords, while a paresis is a partial paralysis. Strangely, there seem to be no patterns for when vocal cord paresis can occur, and happens randomly at any age in any gender from a variety of causes.
The effect such a paralysis can have on life varies greatly, depending upon the career of the individual. A paralysis or paresis of the superior laryngeal nerve (SLN), which is responsible for adjusting the tension of the vocal cords, is what creates abnormalities in voice pitch. Sometimes, a paresis may be fine for normal speaking but cause trouble for other activities, like singing.
The potential cause of a vocal cord paralysis will, in part, determine whether the paralysis/paresis can self-correct over time or if it may be permanent. Even though some causes are known, about half of all cases of paresis are undetectable. In some cases, however, complications may occur from:
- An inadvertent injury during surgery
- A complication from assisted breathing during surgery
- A blunt neck or chest trauma
- Tumors of the skull base, neck, or chest