Bilateral Vocal Cord Paralysis

Etiology

Bilateral vocal cord paresis may be the presenting finding of a pathology that will then progress to true bilateral vocal cord paralysis, but bilateral vocal cord paresis can also be an entity in its own right and nonprogressive, depending on the underlying etiology.[3]

Bilateral Vocal Cord Paralysis Etiolgies

Causes of bilateral vocal cord paralysis include:

• Scarring: Progressive scarring from radiation therapy, prolonged intubation, inhalational burns or caustic ingestions, or inflammatory conditions, eg, scleroderma and relapsing polychondritis, can cause significant progressive scarring in the glottis. This can lead to vocal cord fixation and paralysis, but also can lead to glottic stenosis.

• Iatrogenic causes: In addition to prolonged intubation and scarring as discussed above, postsurgical trauma to the recurrent laryngeal nerve, superior laryngeal nerve, and vagus nerves are the most common causes of bilateral vocal cord paralysis. Classically associated with thyroidectomy, bilateral vocal cord paralysis can also be seen after tracheal resection, esophagectomy, neck exploration for trauma, or congenital heart and aorta surgery.[4]

• Malignancy: Advanced laryngeal malignancy can destroy the vocal cords or their neuromuscular controls, leading to paralysis. Additionally, subglottic, tracheal, esophageal, and thyroid malignancies can extend and involve the recurrent laryngeal nerves, leading to bilateral vocal cord paralysis.

• Central nervous pathology: Stroke, CNS tumor, and multiple sclerosis can all affect the nuclei of the vagus nerve and potentially lead to bilateral vocal cord paralysis. While multiple sclerosis can have a relapsing or remitting course, most CNS causes of this condition carry a very poor chance of recovery of function.[4]

• Systemic disease: ALS, Miller-Fisher, and other systemic syndromes may include bilateral vocal cord paralysis as a component of a systemic condition. A variant of Guillain-Barré can present with isolated bilateral vocal cord paralysis even in the absence of the classic ascending paralysis.

• Idiopathic: This accounts for a significant minority of adult cases of bilateral vocal cord paralysis, though idiopathic bilateral vocal cord paralysis is far rarer in children.[4]

Benninger et al estimated that bilateral vocal cord paralysis can be attributed to surgical trauma in 44% of cases, malignancies in 17%, secondary to endotracheal intubation in 15% of cases, due to neurologic disease in 12% of patients, and idiopathic causes in 12% of cases.[5] Following thyroid or other surgery, a bilateral vocal cord paralysis can result in acute respiratory distress necessitating urgent airway intervention. Damage to the recurrent laryngeal nerve adversely affects both abduction and adduction of the vocal cords due to laryngeal muscle denervation. Since the adductor muscle fibers are 4 times as numerous as the abductor muscle fibers, the vocal cords assume a static paramedian position following injury.[6] Direct stimulation of the vocal cords by an endotracheal tube and cuff during intubation and extubation may lead to vocal cord edema. Case reports have also described injury by direct surgical trauma, nerve division or ligature, pressure-induced neuropraxia, and postoperative edema.[7]

In infants and children with bilateral vocal cord paralysis who primarily present with stridor, Arnold-Chiari malformation II associated with hydrocephalus and myelomeningocele is the most common neurologic finding in infants with bilateral vocal cord paralysis, diagnosed following a magnetic resonance imaging (MRI) scan with cerebellar ectopia below the foramen magnum.[8] Extension of the cerebellar tonsils, brainstem, and medulla through the foramen magnum into the spinal canal leads to vagal nerve compression and bilateral vocal cord dysfunction.[9] Birth-related trauma due to vertex or breech delivery and the use of forceps can also lead to recurrent laryngeal nerve injury, though less commonly a bilateral injury.[10] In infants, cardiovascular surgery, including patent ductus arteriosus ligation and repair of a tracheoesophageal fistula, is a common cause of bilateral vocal cord paralysis.[11]

A palsy of the superior laryngeal nerve causes pitch changes in a patient’s voice secondary to paralysis of the cricothyroid muscle. Bilateral superior laryngeal nerve palsy leads to hoarseness and vocal cord abduction, increasing the risk of aspiration.[12] Although uncommon, vocal cord palsy can also occur in stroke patients with damage to the cerebral cortex or brainstem supplying the vagus, and hence the recurrent laryngeal nerve. Laryngeal dysfunction is secondary to injury of the nucleus ambiguous and nucleus solitarius. In addition, compression secondary to a tumor can cause bilateral recurrent laryngeal nerve palsy, leaving the vocal cords in the paramedian position.

Another extremely rare cause of bilateral recurrent laryngeal nerve paralysis is Guillain-Barré syndrome, the most common acquired demyelinating neuropathy. Although Guillain-Barré syndrome classically presents as loss of deep tendon reflexes with ascending muscular paralysis, cranial nerves can be affected in addition to peripheral nerves. Guillain-Barré syndrome can also manifest with respiratory distress necessitating mechanical ventilation, development of cardiac arrhythmias, and hemodynamic instability.[13]

Epidemiology

Postsurgical nerve injury represents the leading cause of bilateral vocal cord paralysis, with most cases occurring in adults who have undergone thyroid surgery or other bilateral neck procedures. Idiopathic cases may demonstrate a slight female predominance; however, high-quality epidemiologic data remain limited regarding this association.[14]

Although uncommon, vocal cord paralysis remains a recognized cause of neonatal stridor, with most congenital cases presenting as unilateral involvement. Murty et al estimate an incidence of bilateral vocal cord paralysis of 0.75 cases per million births per year.[15] Neonatal bilateral vocal cord paralysis rarely presents in isolation, frequently coexisting with prematurity, bronchopulmonary dysplasia, and neurologic abnormalities, all of which contribute to worsened clinical outcomes in affected infants.

Congenital vocal cord paralysis should remain an important consideration in the differential diagnosis of neonatal respiratory distress.[16] Following laryngomalacia, vocal cord paralysis is the second most common congenital laryngeal abnormality in the pediatric population, although most cases are unilateral. This increased recognition likely reflects improved survival of premature infants and those with complex congenital conditions.[17]

Spontaneous recovery of vocal cord function occurs in approximately 48% to 62% of children with bilateral vocal cord paralysis across all age groups. However, the prognosis depends primarily on overall health status and the presence of associated medical comorbidities.[18]

Pathophysiology

Intrinsic vocal cord or arytenoid scarring and damage result from the replacement of normally mobile laryngeal tissues with fibrosis and scar formation, producing mechanical tethering that restricts mobility and prevents normal vocal cord movement. Recurrent laryngeal nerve injury represents the most common cause of bilateral vocal cord paralysis, warranting a detailed review of its pathophysiology. Vagal motor efferent fibers originate in the medulla oblongata. The nucleus ambiguus contains cell bodies of nerves that innervate the soft palate, pharynx, and larynx, while the dorsal motor nucleus contains visceral efferent fibers that supply the thorax and abdomen. The vagus nerve exits the cranium through the jugular foramen, where the accessory nerve joins its course.[19]

The superior laryngeal nerve branches from the vagus nerve as it descends between the common carotid artery and internal jugular vein, then divides into internal and external branches. The internal branch of the superior laryngeal nerve provides sensory innervation to the mucosa above the true vocal cords, while the external branch innervates the cricothyroid muscle, which plays a key role in the modulation of vocal pitch. The right vagus nerve descends anterior to the subclavian artery into the abdomen, while the right recurrent laryngeal nerve branches off and loops around the subclavian artery before ascending back into the neck toward the larynx.

The right recurrent laryngeal nerve supplies sensory innervation to the laryngeal mucosa below the vocal folds and motor innervation to all intrinsic laryngeal muscles except the cricothyroid. The left vagus nerve follows a similar course into the abdomen posterior to the aortic arch near the ductus arteriosus, with the left recurrent laryngeal nerve branching off and looping around the aorta before ascending through the tracheoesophageal groove to reach the larynx. The longer intrathoracic course of the left recurrent laryngeal nerve increases susceptibility to injury.

Bilateral vocal cord paralysis may result from vagal injury anywhere along its course from the brainstem to the distal thoracic branches. Due to physiologic redundancy within laryngeal innervation, vocal cord position does not always reliably localize the lesion in bilateral paralysis.[20] Recurrent laryngeal nerve injury remains the most common mechanism, classically producing a paramedian vocal cord position in unilateral cases and a median position in bilateral cases. Superior laryngeal nerve injury reduces vocal pitch and may produce vocal cord bowing due to loss of cricothyroid muscle tone. High vagal injury may result in a nearly fully abducted “cadaveric” vocal cord position.[19]

History and Physical

Adults Bilateral Vocal Cord Paralysis

The primary presenting complaints of an adult patient with bilateral vocal cord paralysis are either voice changes (eg, hoarseness, pitch changes, vocal fatigue) or, more commonly, breathing difficulties (eg, stridor, increased work of breathing, aspiration/pneumonia).[21] A history of the onset and duration of symptoms should be obtained, as well as whether they are progressing or stable. Furthermore, any antecedent events should be documented, including prior upper respiratory infection, any neck surgery or trauma, malignancy, radiation therapy, and a thorough past medical history should be obtained. Of particular interest are any systemic rheumatologic or connective tissue disease and any immunosuppression.

Additionally, a thorough physical exam is required, with an emphasis on the head and neck and lung examination. Breathing and the patient's voice at rest and with effort should be noted. After a patient has been speaking for a few minutes, the inspiratory stridor may become evident or worsen. Diagnosis is made clinically based on flexible fiberoptic laryngoscopy, in which the vocal cords are observed to be immobile, and their position is noted. If the diagnosis remains uncertain, video stroboscopy and bronchoscopy can provide additional information about the fluid wave of vocal cord vibration and help rule out subglottic and tracheal pathology, eg, subglottic stenosis or tracheomalacia.

Pediatric Bilateral Vocal Cord Paralysis

In pediatric patients, a detailed family and birth history, including prolonged or protracted delivery, assistive devices used during delivery, concurrent congenital medical problems, and the length of any NICU stay, should be obtained. The remaining pertinent points of history are similar to those of adult patients. Bilateral vocal cord paralysis in pediatric patients often presents with stridor and feeding difficulties, and children with congenital bilateral vocal cord paralysis are more likely to exhibit severe manifestations, eg, cyanosis and apnea. Notably, children with bilateral vocal cord paralysis often present with a normal voice because the vocal cords remain in the paramedian position with abductor paralysis, but can have marked inspiratory stridor and accessory muscle use with inspiration.

Diagnosis is usually made via awake fiberoptic laryngoscopy, which is possible even in very small children, though more challenging than in adults. This will also rule out laryngomalacia, which is far more common than bilateral vocal cord paralysis but can present with similar symptoms. If the diagnosis is still uncertain, direct laryngoscopy and bronchoscopy under anesthesia may be required. direct laryngoscopy and bronchoscopy is performed with the patient spontaneously breathing, so the motion of the vocal cords can be assessed intraoperatively. This modaliety also allows for lower airway examination to rule out concurrent or alternative pathology, eg, subglottic stenosis and tracheomalacia or bronchomalacia.[19]

Evaluation

Diagnostic studies that are utilized in the evaluation of bilateral vocal cord paralysis include:

• Flexible fiberoptic laryngoscopy: This study is an essential part of the initial evaluation of patients presenting with features of vocal cord paralysis. Flexible fiberoptic laryngoscopy is performed with the patient awake in the office to assess spontaneous and volitional vocal cord movement.[11]

• Direct laryngoscopy and bronchoscopy: If the status of the vocal cords or of the lower airway is uncertain, examination with direct laryngoscopy and bronchoscopy is indicated. This study also allows palpation of the arytenoid joints to rule out fixation.

• Laryngeal electromyography: This diagnostic modality is performed with the patient awake in the office to assess the innervation status of the laryngeal muscles, which can help determine the duration of paralysis and recovery potential after a neurologic injury. Please see StatPearls' companion resource, "Nerve Conduction Studies and Electromyography," for further information on electromyography interpretation.[22][23]

• Imaging of the recurrent laryngeal nerve: In a patient with new-onset, idiopathic bilateral vocal cord paralysis, the entire course of the recurrent laryngeal nerves must be imaged to rule out a tumor or CNS pathology. Computed tomography (CT) is the most commonly employed modality, though magnetic resonance imaging (MRI) can also be used. The area to be imaged is from the high brainstem (nuclei of the vagus nerve) to the aorta (inferior-most course of the left recurrent laryngeal nerve).

• Laboratory testing: No single laboratory study is used to diagnose bilateral vocal cord paralysis, and the investigations to consider are guided by each patient's history and overall medical picture. Potassium, calcium, glucose, antineutrophil cytoplasmic antibody test, thyroid function tests, Lyme disease titers, tuberculosis skin tests, uric acid levels, rheumatoid factor test, antinuclear antibody tests, and erythrocyte sedimentation rate can all be considered.

Treatment / Management

Although surgical intervention is commonly indicated in patients with bilateral vocal cord paralysis, medical management of inflammatory and infectious conditions, eg, syphilis, tuberculosis, gout, and relapsing polychondritis, is essential. Corticosteroids are effective in conditions such as sarcoidosis, polychondritis, and Wegener granulomatosis. Glucose management is imperative to aid neuropathy in patients with diabetes mellitus. Management of reflux is often recommended during the recovery period to minimize untoward irritation of the larynx.

More than 50% of children will experience spontaneous symptom resolution within the first 12 months of life. However, the prognosis is much more guarded for bilateral vocal cord paralysis when compared to unilateral.[24] This fact must be taken into consideration before any invasive intervention that can impact a patient’s ability to phonate or swallow. In adults, the prognosis depends much more on the etiology, and additional studies (eg, electromyelography) can have predictive value in postoperative cases to assess the likelihood of recovery. If the patient is experiencing increased work of breathing or significant stridor, some form of surgical intervention to improve the airway will be required, even if spontaneous recovery is expected. If the prognosis for recovery is favorable, a reversible procedure, eg, a botulinum toxin injection or a tracheostomy, should be performed. If minimal or no recovery is expected, laryngeal surgery can be considered to attempt decannulation.[25](B2)

Tracheostomy

In the past, tracheostomy was the most common procedure performed in patients with bilateral vocal cords to establish a secure airway. Tracheostomy provides the largest airway diameter and preserves laryngeal structure, so this procedure is potentially reversible without long-term sequelae. Although tracheostomy remains the standard in settings of glottic obstruction, this intervention is associated with significant chronic care burden, cost, psychosocial impairment, and increased mortality. Studies have noted that patients experienced a reduced quality of life and must undergo continuous management of their tracheostomies, which can be particularly undesirable in children.[26] (A1)

In a national series of 885 infants undergoing tracheostomy, the in-hospital mortality was 14%.[27] Endoscopic techniques have been shown to be more cost-effective than tracheostomy in the management of permanent bilateral vocal cord paralysis.[28] Although several alternative procedures have been developed to manage bilateral vocal cord paralysis, they all can produce permanent changes of the larynx that may predispose patients to lifelong aspiration and dysphonia postoperatively.[29](A1)

Botulinum Toxin

Botulinum toxin, produced by Clostridium botulinum, is a neurotoxin that prevents the release of acetylcholine from presynaptic axon terminals, leading to flaccid paralysis of the target muscle. For patients with vocal cord paralysis, toxin injection is utilized to block aberrant reinnervation of adductor muscles by inspiratory motor neurons. This enables abductor inspiratory motor neurons to become more effective, thereby facilitating glottic opening.[30] This technique only affects a transient improvement in symptoms for approximately 3 to 6 months at a time, requiring repeated injections for longer-lasting relief. Botulinum toxin is a viable option in idiopathic spasmodic vocal cord dysfunction, or in cases where complete recovery of function is expected but at a protracted rate.(B2)

Arytenoidectomy

Arytenoidectomy is an irreversible procedure involving the endoscopic removal of the arytenoid cartilage (sometimes only the prolapsed cuneiform cartilages are removed) to expand the glottic inlet transversely, creating a larger-diameter airway for inspiration.[31][23][31] Arytenoidectomy is performed either on its own or in combination with vocal fold resection, in which case this procedure is referred to as arytenoid cordectomy. Resection of the mucosa and cuneiform cartilage over the arytenoid leads to a widening of the glottis. This technique has demonstrated positive results in augmenting ventilation in patients with bilateral vocal cord paralysis, particularly in pediatric patients.(A1)

Further refinement of arytenoidectomy techniques occurred with the introduction of the CO₂ laser, which improved procedural precision while enhancing hemostasis and reducing postoperative edema.[32] Despite these advances, some patients experience worsening postoperative dysphonia following arytenoidectomy, and these voice changes may become permanent.[33] The procedure also increases susceptibility to scar formation and granuloma development, both of which may contribute to progressive airway narrowing and necessitate multiple surgical revisions.

Endoscopic laser resection techniques offer the advantage of avoiding tracheostomy placement in many patients undergoing surgical airway enlargement. In one study, utilization of an endoscopic plasma coblator instead of a CO₂ laser resulted in reduced scar formation, likely secondary to decreased thermal injury to adjacent tissues.[34](B3)

Cordotomy

Cordotomy is another endoscopic surgical procedure to enlarge the glottic airway. A cordotomy is accomplished via an incision of the vocal fold, ligament, and the thyroarytenoid muscle posteriorly at the attachment to the arytenoid. Cordotomy, similar to arytenoidectomy, is susceptible to granuloma and scar formation. Revision cordotomy can be required in up to 30% of patients secondary to reduced glottic diameter from scarring or granulation tissue formation.[35] The most common complication associated with cordotomy was altered voice quality due to vocal fold damage.[36] Laser endoscopic cordotomy has become the favored therapeutic intervention for vocal cord paralysis as compared to an arytenoidectomy, as cordotomy is less invasive and reduces the incidence of aspiration. Voice quality can be impaired after resection, but overall voice outcomes are often superior to arytenoidectomy, particularly in adult patients.[35](B2)

Reinnervation

The goal of reinnervation is to establish vocal cord abduction through the restoration of the activity of the posterior cricoarytenoid (PCA) muscle. While this procedure enables the return of spontaneous vocal cord abduction, it does not affect adduction. Anastomosis of the recurrent laryngeal nerve is a complex procedure due to the variability and complexity of its innervation.[2] The phrenic nerve has been used to reinnervate the PCA muscle; in one study, inspiratory vocal fold abduction was achieved in 93% of cases.[37] (B3)

Although patients had hemidiaphragm paralysis, they had substantial recovery of diaphragmatic motion and respiratory function within 12 months. Marina et al previously showed that only a branch of the phrenic nerve could be used to minimize loss of diaphragmatic function and maintain respiratory parameters.[2] A more modern technique is the use of a pedicled neuromuscular flap from the ansa cervicalis, avoiding the diaphragmatic complications of the phrenic nerve sacrifice. This procedure is technically very challenging and is most successful when performed by a few surgeons with significant experience in its use. All of these laryngeal reinnervation procedures are far more commonly used in unilateral vocal cord paralysis.[38][3](B3)

Gene Therapy

Gene therapy remains in the preclinical phases but holds several promising avenues for future treatment. With this technique, gene delivery to injured or denervated muscles promotes the growth of damaged neurons, aiding the rejuvenation of damaged laryngeal muscles. These genes encode neurotrophic or growth factors that stimulate muscle differentiation and proliferation.[39] Either delivered directly into the laryngeal muscles or into the recurrent laryngeal nerve, they are absorbed by neuronal cell bodies through retrograde axonal transport.[40] Once appropriately transduced into target cells, they produce peptides that promote the growth of the recurrent laryngeal nerve, synaptic formation, and regeneration.[3](B3)

Differential Diagnosis

Differential diagnoses that should also be considered when evaluating bilateral vocal cord paralysis 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
• Arnold-Chiari malformation
• Meningomyelocele
• Diabetes mellitus
• Amyotrophic lateral sclerosis
• Myasthenia gravis
• Möbius syndrome
• Charcot-Marie-Tooth disease
• Postpolio syndrome
• Shy-Drager syndrome
• Creutzfeldt-Jakob disease
• Hydrocephalus
• Synkinesis of the recurrent laryngeal nerve
• Lyme disease
• Radiation therapy
• Postirradiation fibrosis of the cricoarytenoid joint, vocal folds, or both
• Chondronecrosis
• Hypokalemia
• Hypocalcemia
• Diabetes mellitus
• Renal insufficiency with Alport syndrome

Additionally, etiologies that should be considered are complications following surgical intervention, including:

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

Prognosis

In adults, recovery of idiopathic vocal cord paralysis (or vocal cord paralysis due to nontransecting nerve injury) can occur as early as 12 months following injury. Although spontaneous recovery is expected in 55% of patients, full recovery can be very protracted. The prognosis for complete spontaneous recovery is far worse in bilateral vocal cord paralysis than unilateral. Recovery of glottic function is otherwise most dependent on the underlying etiology, and the overall prognosis of this root cause.[41]

Complications

Vocal cord paralysis can lead to the following complications:

• Altered voice quality
• Weak cough
• Difficulty swallowing
• Feeding difficulty
• Hoarseness 
• Stridor
• Dyspnea
• Aspiration risk
• Airway obstruction
• Granuloma Formation
• Arytenoid Chondritis
• Reduced quality of life associated with tracheostomy [29]
• Laser-related airway fire
• Scar formation
• Airway management difficulties [42]