What is Bilateral Vocal Cord Paralysis?

Vocal cord paralysis means the vocal cord can’t move, while vocal cord paresis means the vocal cord’s movement is impaired. These conditions can be due to issues inside the vocal cord itself (such as scars or tumors), nerve problems from specific nerves that control vocal cord movement, brain problems (like stroke, tumor, or multiple sclerosis), or general body diseases (like ALS or Guillain-Barre syndrome). Vocal cord paralysis is typically one-sided, but in this case, we’re talking about the less common condition where both vocal cords are paralyzed.

The voice cords have two main jobs: making sound (for talking) and protecting the lower part of our airways. The symptoms a patient feels will depend on why their vocal cords are paralyzed and what position they are stuck in. If the cords are stuck in a central position, the patient might have trouble breathing, no symptoms at all, or have a normal voice and don’t experience food or drink entering their lungs. But if the cords are stuck in a more outward position, the patient’s airway remains open and they might complain about a breathy voice, potentially experience choking, but typically have less breathing difficulties. The way this condition is managed will rely on the underlying cause and position of the vocal cords, as well as how the patient is expected to recover from this condition in the future.

What Causes Bilateral Vocal Cord Paralysis?

Your vocal cords, which enable you to speak, can become weak or damaged on both sides leading to a condition known as bilateral vocal cord paresis. This condition could further deteriorate into bilateral vocal cord paralysis, where your voice cords lose all function. However, in some cases, this paresis may not progress.

There are several possible reasons for vocal cord paresis:

1. Scarring: Scarring can interfere with how your vocal cords move. This could be from radiotherapy, scars from tubes left in your throat for too long, injury from inhaling harmful substances, or conditions like relapsing polychondritis. In severe cases, it can continue to the point of closing your voice box.
2. Medical procedures: Procedures could cause damage to nerves controlling the voice box, weakening your vocal cord function. Typically, we see this from surgeries for thyroid, trachea, and esophagus conditions.
3. Cancer: Early stages of cancer within the throat can reduce how the vocal cords move. If not treated, the blockage from the tumor can lead to vocal cord paralysis or block your airway.
4. Nervous system issues: Conditions such as stroke, brain tumors, multiple sclerosis (MS), can affect the nerves controlling the vocal cords, causing weakness or paralysis.
5. Overall body condition: Diseases that affect the whole body, like Amyotrophic Lateral Sclerosis (ALS) and Guillain-Barre syndrome can result in vocal cord weakness.

When the paralysis affects both sides of the vocal cords, the possible reasons include:

1. Scarring: As with paresis, extreme scarring from radiation therapy, prolonged intubation, inhaling harmful substances, inflammatory conditions like scleroderma and relapsing polychondritis, can lead to permanent vocal cord paralysis.
2. Medical Procedures: This can lead to injuries to the nerves controlling the vocal cords, causing paralysis.
3. Cancer: Advanced throat cancer can damage the vocal cords or the nerves and muscles controlling them. Also, cancer in the area below the vocal cords, windpipe, esophagus, and thyroid can impact these controlling nerves resulting in bilateral vocal cord paralysis.
4. Nervous system issues: Stroke, brain tumors, and MS, can damage the vagus nerve, possibly leading to vocal cord paralysis.
5. Overall body conditions: Diseases like ALS, and Miller-Fisher syndrome can lead to vocal cord paralysis.
6. Unknown causes: Sometimes, the cause of the paralysis is unknown but it’s rare in children.

Studies estimate that surgical damage accounts for 44% of vocal cord paralysis cases, cancer for 17%, intubation for 15%, neurological disease for 12%, with unknown causes making up the other 12%.

In infants and children, bilateral vocal cord paralysis often shows as a noisy, high-pitched breathing called stridor. A brain disorder called Arnold-Chiari malformation II is the most common neurological cause in children, which can be diagnosed with an MRI scan. Birth-related trauma and cardiovascular surgeries are also common causes in infants.

Any damage to the superior laryngeal nerve can also affect your voice by paralyzing the cricothyroid muscle – this muscle controls the pitch and volume of the voice. Also, stroke or tumors can result in paralysis by injuring the areas that control the vagus nerve, and hence the vocal cords. A rare cause is Guillain Barre Syndrome – a condition that affects the nerves – which classically presents as loss of deep tendon reflexes with ascending muscular paralysis but can also affect the vocal cords.

Risk Factors and Frequency for Bilateral Vocal Cord Paralysis

Bilateral vocal cord paralysis, often a result of surgery-related nerve injury, is mostly found in adults who have undergone thyroid or other bilateral neck surgeries. While the cause can sometimes be unknown, it’s slightly more prevalent in females, although this needs more research for confirmation.

This condition, though rare, is also a known cause of stridor (a high-pitched, wheezing sound) in newborns. However, most newborn cases involve only one vocal cord. According to Murty and team, the occurrence of paralysis in both cords in newborns is about 0.75 cases per million births each year. This is seldom seen on its own in newborns and is often accompanied by other factors such as being born early, lung disease, and neurological issues, which may worsen infants’ health outcomes. Doctors should consider congenital vocal cord paralysis when treating a baby with difficulty breathing.

Following laryngomalacia (softening of the voice box), vocal cord paralysis is the second most common voice box abnormality in children, though it most often affects only one vocal cord. This could be due to increased survival of premature infants and those with complex conditions present from birth.

Stridor, a type of wheezing sound, can be caused by vocal cord paralysis in newborns.
In newborns, most cases of vocal cord paralysis involve only one vocal cord.
About 0.75 cases per million births each year involve paralysis in both cords in newborns.
Newborns with dual cord paralysis often have other health problems such as prematurity, lung disease, and neurological issues.
Vocal cord paralysis is the second most common abnormality of the voice box in children, likely due to increased survival rates of premature infants and infants with complex congenital disabilities.

In children of all ages with bilateral vocal cord paralysis, there’s a 48% to 62% chance of their vocal cords spontaneously recovering. However, the child’s overall health and accompanying medical issues significantly affect their recovery chances.

Signs and Symptoms of Bilateral Vocal Cord Paralysis

When adults have bilateral vocal cord paralysis, the main symptoms usually include voice changes like hoarseness, alterations in pitch, vocal fatigue, and breathing difficulties such as breathy voice and aspiration pneumonia. It’s important to understand when these symptoms began and how long they have lasted, as well as any relevant past events like neck injuries or surgeries, radiation therapy or other medical conditions, particularly problems with the immune system or connective tissue diseases. Doctors will focus on examining the head, neck and lungs, and observe changes in voice and breathing when at rest as well as during physical effort.

Diagnosis typically involves a procedure called flexible fiberoptic laryngoscopy where the position of the vocal cords can be closely examined. If the doctor is unable to make a diagnosis with this method, additional procedures using video stroboscopy and bronchoscopy may provide more information and rule out other conditions such as subglottic stenosis or tracheomalacia.

In children, bilateral vocal cord paralysis usually shows up as noisy breathing or stridor, and feeding problems. It’s essential to document a detailed family and birth history, including any complications during delivery or medical issues present at birth. Children suffering from this condition may have a normal voice due because the vocal cords stay in a middle position; however, difficulties with breathing are often noticeable.

Doctors usually use awake fiberoptic laryngoscopy for diagnosing this in children, although it’s a bit more challenging than in adults. This method helps to rule out other more common conditions like laryngomalacia that can show similar symptoms. If the condition is still unclear, other procedures like direct laryngoscopy and bronchoscopy under anesthesia may be performed. These procedures enable doctors to assess the movement of the vocal cords and check for other possible conditions affecting the lower airways.

Testing for Bilateral Vocal Cord Paralysis

If your doctor suspects that you may be experiencing bilateral vocal cord paralysis or have problems with your lower airway, they could use several tests to assist them in diagnosing your condition. These tests include:

– Flexible fiberoptic laryngoscopy: This test can be done while you’re awake at the doctor’s office. It lets the doctor look at how your vocal cords move when you’re not trying to control them. This happens to be an essential part of the initial physical examination.

– Direct laryngoscopy and bronchoscopy: These tests might be needed if there’s uncertainty about your vocal cords’ state or your lower airway. This process also allows the doctor to physically feel the arytenoid joints (joints in your throat) to make sure they aren’t stuck or fixed in place.

– Laryngeal electromyography: This test checks the nerves that control the muscles in your larynx (or voice box). It’s performed while you’re awake at the doctor’s office, and it can provide good information about how long you’ve had paralysis and how likely you are to recover after an injury to the nerves. The process of interpreting the results of this test is called electromyography.

– Imaging of the recurrent laryngeal nerve: If your vocal cords have suddenly become paralyzed and your doctor isn’t sure why, they might need to take pictures of the nerves that control your vocal cords to see if a tumor or disease is causing the problem. CT scans are the most common way to do this, but MRI scans can also be used. The scans would look at everything from the high brainstem (a part of your brain where the vagus nerve begins) to the aorta (near your heart, where the left recurrent laryngeal nerve loops around).

– Lab tests: There isn’t any one specific lab test for bilateral vocal cord paralysis. Instead, your doctor might use a variety of tests depending on your unique symptoms and medical history. These could include tests for potassium, calcium, glucose, thyroid function, lyme disease, tuberculosis, uric acid levels, and several others tied to inflammation and immune system function.

Treatment Options for Bilateral Vocal Cord Paralysis

For patients with bilateral vocal cord paralysis (paralysis of both vocal cords), there are various treatment options including surgical intervention and medical management. Management is particularly focused on treating infectious and inflammatory conditions such as syphilis, tuberculosis, gout, and relapsing polychondritis, a type of arthritis that affects your cartilage. Inflammatory conditions such as sarcoidosis, Wegener’s granulomatosis, and polychondritis can be tackled efficiently using medications like corticosteroids. If the paralysis is a result of diabetes mellitus, managing your glucose level is critical. It can help improve neuropathy, a type of nerve damage that can result in vocal cord paralysis. These treatments help to minimize the possible harmful effect on the larynx during the recovery period.

On the positive side, more than half of the children diagnosed with vocal cord paralysis will experience natural symptom relief within the first year of their lives. However, the predicted outcome is less positive when both vocal cords are paralyzed compared to just a single one. This is a crucial point to consider when choosing treatment options that may affect the patient’s ability to phonate (produce sound) or swallow. For adults, the prognosis will rely significantly on the cause of the paralysis. Likewise, some tests such as an Electromyography (EMG), a test that measures muscle response, can predict the possibility of recovery after surgery.

Historically, tracheostomy, a surgery to create an opening in the neck for direct access to the windpipe, was the most common procedure for patients with bilateral vocal cord paralysis to ensure a safe airway. However, despite providing the largest airway diameter and preserving laryngeal structure, it is associated with significant burdens including reduced quality of life and increased cost.

Botulinum toxin, which is a toxin that causes muscles to become weak, has also been used for treatment by blocking unnecessary reinnervation of adductor muscles, which close the vocal folds. This treatment is temporary, providing improvement for about three to six months and may need to be repeated for long-term relief. It is often utilized in cases where complete recovery is expected but may take a longer time.

Other irreversible surgical options include Arytenoidectomy and Cordotomy. Arytenoidectomy involves removing arytenoid cartilage to expand the glottic inlet and increase the airway’s diameter for inspiration. Cordotomy, on the other hand, is a surgical procedure to enlarge the glottic airway by incising the vocal folds and relevant muscles. Both of these, while expanding the airway, can leave a patient susceptible to scar tissue development, and in some cases, potentially changing voice quality.

Reinnervation refers to the restoration of nerve supply, which has the potential to return spontaneous vocal cord abduction, the opening of the vocal folds. However, due to the complex nature of the nerve supply, this procedure is complicated and difficult.

Gene therapy, while still in the experimental stage, shows potential for treating vocal cord paralysis in the future. This method involves delivering genes that stimulate muscle growth to damaged laryngeal muscles or into the Recurrent Laryngeal Nerve (RLN), the nerve that controls the larynx. Once absorbed by neuronal cell bodies, they produce peptides, which are amino acids responsible for promoting RLN growth, connect neurons, and encourage regeneration.

There are many potential causes of certain health conditions that doctors may need to consider. These can include:

Unilateral vocal cord paralysis
Subglottic stenosis
Laryngomalacia
Rheumatoid arthritis
Gout
Tietze syndrome
Ankylosing spondylitis
Reiter syndrome
Crohn disease
Collagen vascular disease
Mumps
Systemic lupus erythematosus
Wegener granulomatosis
Amyloidosis
Sarcoidosis
Cicatricial pemphigoid
Tuberculosis
Syphilis
Gastroesophageal reflux disease
Relapsing polychondritis
Laryngeal neoplasm
Chondromas and chondrosarcomas
Squamous cell carcinoma

Also, certain surgical procedures can lead to health complications. These might include:

Thyroid surgery
Parathyroid surgery
Esophageal surgery
Tracheal surgery
Brainstem surgery
Carotid endarterectomy

Other potential causes are:

Arnold-Chiari malformation
Meningomyelocele
Diabetes mellitus
Amyotrophic lateral sclerosis
Myasthenia gravis
Möbius syndrome
Charcot-Marie-Tooth disease
Postpolio syndrome
Shy-Drager syndrome
Creutzfeldt-Jacob disease
Hydrocephalus
RLN synkinesis
Lyme disease
Radiation therapy
Postirradiation fibrosis of the cricoarytenoid joint, vocal folds, or both
Chondronecrosis
Hypokalemia
Hypocalcemia
Diabetes mellitus
Renal insufficiency with Alport syndrome

What to expect with Bilateral Vocal Cord Paralysis

In adults, idiopathic vocal cord paralysis, or vocal cord paralysis from a non-cutting nerve injury, can start to get better as early as 12 months after the injury. Although 55% of patients are expected to recover naturally, full recovery can take a considerably long time. If both vocal cords are paralyzed, it’s less likely for a complete spontaneous recovery compared to if only one vocal cord is paralyzed.

The recovery of the glottic function, which is responsible for sound production, largely depends on the root cause of the problem. The chances of full recovery also rely heavily on the overall prognosis or outlook of this root cause.

Possible Complications When Diagnosed with Bilateral Vocal Cord Paralysis

If your vocal cords become paralyzed, it can lead to several complications. Some of these may affect your daily life and hinder your ability to perform everyday tasks.

Here are the most common complications you might experience: