Vocal Cord Paralysis, Unilateral

Unilateral vocal cord paralysis is the neurogenic inability of one vocal cord to move. It is associated with weak voice of a degree that can vary between individuals.

See also: vocal cord paralysis, bilateral.

What Causes Vocal Cord Paralysis?

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.

Vocal Cord Paralysis Defined by 3 Individual Muscles Denervated rather than as Recurrent Nerve Non-Function

Vocal cord paralysis is ordinarily defined as an immobile cord and thoughts go directly to recurrent nerve injury. The visual “definition” most universally used is loss of abduction (though there is also loss of medial compression). Said another way, we tend to think of the recurrent nerve being “out” but not so much of the three individual muscles that are denervated as a consequence. By contrast, paresis is defined by which one (or two) of the following muscles is/are denervated:

1. Posterior cricoarytenoid (PCA)
2. Lateral cricoarytenoid (LCA)
3. Thyroarytenoid (TA)

But returning to the term “paralysis,” it could be defined as denervation of all three muscles: PCA, LCA, and TA. This is shown clearly in the following set of images. Note that we typically leave out the interarytenoid (IA) muscle because it is bilaterally innervated and doesn’t often seem to figure in vocal cord paralysis.

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 (Injection Laryngoplasty) – 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.