Vocal cord paresis is the partial loss of voluntary motion for one or more of the muscles that move the vocal cords. Paresis is to be distinguished from paralysis, which refers to a complete loss of motion. Sometimes, however, the terms “paralysis” or “paralyzed” are used less precisely to encompass any kind of loss of motion, partial or complete. But we prefer the term “paresis” whenever it applies, and below we suggest a way to use this term when describing more complicated cases of vocal cords with reduced or no mobility.
Paresis or paralysis of a muscle or muscle group is caused by damage to its nerve supply. In other words, the underlying cause of a paretic or paralyzed muscle’s immobility is not a disorder of that muscle per se, but a disorder of the nerve supplying that muscle. Perhaps for this reason, it is common to speak of paralysis according to the nerve involved, rather than the muscle or muscles; in the world of laryngology, for example, we speak of “paralysis of the recurrent nerve.” However, it seems more logical to describe paralysis or paresis according to what is actually immobilized: the muscles. For example: if in a given case only the posterior cricoarytenoid (PCA) muscle is immobilized, then instead of calling that “paralysis of the recurrent nerve,” we would call it “PCA-only vocal cord paresis.”
In that example, though, some might wonder if it would be better for us to say “paralysis” instead of “paresis.” In other words, should we describe the nature of the immobility of the PCA muscle alone (so that, if the PCA is totally immobile, we would say “PCA-only vocal cord paralysis”) or that of the vocal cord’s entire set of muscles (which as a group is only partially immobile, so we would stick with “PCA-only vocal cord paresis”)? We think that, in general, it is more helpful to do the latter. To illustrate, here is an imaginary conversation: “Is this vocal cord paralyzed or paretic?” “Paretic.” “Which kind of paresis is it?” “PCA-only.”
It is surprisingly easy to diagnose the different variants of vocal cord paresis with a straightforward visual examination. Click on a particular variant to learn more:
- Vocal cord paresis, TA + LCA
- Vocal cord paresis, TA-only
- Vocal cord paresis, LCA-only
- Vocal cord paresis, PCA-only
- Vocal cord paresis, IA-only
Vocal Cord Paresis (Thyroarytenoid Muscle) Accentuated by Disuse
High Vagus Nerve Injury
The vagus (10th cranial) nerve originates from the medulla (part of the brainstem), exits from the base of the skull through the jugular foramen, and among other things, supplies branches to the musculature of palate, pharynx, and larynx. Location of vagus nerve injury is sometimes evident by palate and pharynx findings. But these findings are sometimes overlooked as in this case, especially if palate and pharynx are weak but not completely paralyzed.
Case study: This 50-something woman developed a weak voice and moderate difficulty swallowing upon awakening 5 months prior to this visit. Fortunately, her symptoms of weak voice and difficulty swallowing were not devastating, and are improving. But up to this examination, there has been no diagnosis. This examination reveals a “lesion” of her right vagus nerve and it has to be at the base of the skull because palate, pharynx, and larynx muscles are all weak. Voice is functional but lacks the ability to project and has a “soft-edged” quality. A sophisticated listener can also hear mild hypernasality. The examination below prompts a scan with special attention to base of skull to be sure there is no mass lesion there.