Vocal Cord Paresis

Paresis vs. Paralysis

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.”

Types of Paresis

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

What Causes Paresis?

If the recurrent laryngeal nerve gets damaged anywhere along the way from brainstem to larynx, then some or all of the vocal cord muscles might be weakened (paretic) or completely immobilized (paralyzed), thereby affecting the person’s voice or breathing.

 Can the Nerve Recover on Its Own?

If the damaged nerve is still intact, then it may recover on its own, either completely or at least enough to meet the person’s vocal needs. This recovery can take up to a year because neural tissue heals much more slowly than skin or even bone.

Sometimes, though, the nerve does not recover, or not enough to meet the person’s vocal needs. There is no need to wait for a potential recovery if a tumor has invaded the nerve or if the nerve is known to be severed.

Symptoms

One of the most common scenarios is that after investigation the cause is unknown—we call these cases idiopathic. In these cases, a virus is suspected to have played a role.

Two other causes of paresis or paralysis are tumors and trauma. Tumors in these cases could be in the thyroid, lung, esophagus, etc. Trauma is often from surgery that is performed along the path of the vagus nerve, such as for thyroid, spine, lung, or heart problems.

Other symptoms may include:

• Weak, air-wasting dysphonia – The voice may be breathy, weak, double-pitched, or manifest luffing. The person may only be able to say a few words on a breath or be unable to project the voice in noisy places.
• Inability to be heard in noisy locations.
• A tendency of the voice to be somewhat stronger in the morning but to “fade” with use.
• A tendency to cough when drinking thin liquids.

Testing That May Be Done

Laryngeal videostroboscopy

When performed at close range, this examination helps to determine which muscles are affected.

CT scan

This test helps to rule out mass lesions along the course of the nerve. A CT scan is not necessary if the cause is already known (e.g., thyroid surgery).

EMG

This is optional/controversial, and not needed in clinics where a close-range laryngeal videostroboscopy is performed.

Treatment Options

1. Do nothing

   Just accept the symptoms while waiting, especially if recovery is thought to be possible (such as after thyroid surgery with an intact nerve, or after a presumed viral injury).

2. Vocal exercise with a speech pathologist

   Usually helpful if the patient is taciturn. Some patients are mistakenly advised (by well-intentioned family or friends) to rest their voices. Voice rest is in fact counterproductive, except when the general fatigue caused by use of an air-wasting voice makes brief voice rest appropriate.

3. Voice gel – an injected implant that is slowly absorbed and therefore temporary

   This is not for definitive voice restoration, but can offer a boost while awaiting possible recovery. The aim is for modest or better benefit.

   Voice gel implants are often done in-office with topical anesthesia and, occasionally, mild sedation. The gel material—hyaluronic acid—infiltrates the tissue to plump and firm so that the other vocal cord has something to push against.

   Duration of benefit is typically four to twelve weeks as the gel slowly absorbs. The hope is that nerve recovery occurs during this time, but injection can be repeated if its benefit fades before it is appropriate to place a permanent implant.

4. Voice gel + hydroxyapatite — A semi-permanent injected implant

   This option is used mostly if the patient does not want a medialization laryngoplasty (option #5 below). If placement of the filler is not ideal, a surgical adjustment might be necessary.

5. Medialization laryngoplasty with a silastic implant

   This is performed in an outpatient operating room under local anesthesia with deep sedation (“twilight”). Surgery requires a horizontal one-inch incision on the front of the neck, and involves placement of a wedge or “shim” to permanently medialize and firm up the paralyzed vocal cord.

   There are small risks of bruising and infection. Approximately one out of ten patients needs a second trip to the operating room to adjust the implant.