Laryngeal Paralysis

Laryngeal paralysis, most often vocal fold (vocal cord) paralysis, is the loss of normal movement of one or both vocal folds because of impaired nerve supply to the laryngeal muscles. Because the affected fold cannot move to its proper position, the condition disturbs voice, can compromise the airway when both folds are involved, and may impair the protective closure that guards the airway during swallowing.

Definition

Laryngeal paralysis is impaired or absent movement of one or both vocal folds resulting from dysfunction of the vagus nerve or its recurrent (or superior) laryngeal branches, producing characteristic effects on voice, airway, and airway protection depending on whether one or both folds are affected.

Scope

This topic covers the neural basis of vocal fold immobility, the distinction between unilateral and bilateral paralysis and their contrasting consequences, the major etiologic categories (surgical injury, malignancy, neurological disease, and idiopathic cases), and the general principles of evaluation. It is reference-educational and does not provide individualized management guidance.

Core questions

• How does injury to the recurrent laryngeal nerve translate into vocal fold immobility?
• Why do unilateral and bilateral paralysis present so differently?
• What are the major causes of vocal fold immobility and how has their distribution changed?
• How is paralysis distinguished from mechanical fixation of the joint?

Key concepts

• Recurrent laryngeal nerve
• Vagus and superior laryngeal nerve
• Unilateral vocal fold paralysis
• Bilateral vocal fold paralysis
• Glottic incompetence and breathy voice
• Airway compromise
• Vocal fold immobility versus fixation

Mechanisms

The intrinsic laryngeal muscles that abduct and adduct the vocal folds are supplied mainly by the recurrent laryngeal nerve, a branch of the vagus that follows a long course through the neck and chest. Interruption anywhere along this pathway — from the brainstem to the nerve in the neck — leaves the affected fold unable to move. In unilateral paralysis the immobile fold fails to meet its partner, leaving a glottic gap that produces a breathy, weak voice and can allow aspiration during swallowing. In bilateral paralysis both folds tend to rest near the midline, so voice may be relatively preserved but the airway can be dangerously narrowed. Paralysis (a neural problem) must be distinguished from cricoarytenoid joint fixation, which mechanically limits movement despite intact nerves (flint-cummings-2020).

Clinical relevance

Vocal fold paralysis is an important cause of dysphonia and, when bilateral, of airway compromise, and its recognition prompts a search for an underlying cause such as recent surgery, a mass along the nerve's course, or neurological disease. This entry describes the condition and its evaluation as reference material and is not a basis for individualized diagnosis or treatment.

Epidemiology

Surgical injury — particularly thyroid and other neck, chest, and skull-base procedures — and malignancy are leading causes of vocal fold immobility, with neurological disease, trauma, and idiopathic cases also contributing; the relative distribution of causes has shifted over time as surgical and oncologic practice has changed (benninger-1998).

History

The link between recurrent laryngeal nerve injury and vocal fold immobility has been recognized since classical descriptions of the nerve's anatomy, and the etiologic spectrum has been repeatedly re-characterized as medicine evolved. Series spanning decades documented a changing distribution of causes, reflecting the rise of thoracic and thyroid surgery and changing patterns of malignancy and idiopathic diagnosis (benninger-1998; flint-cummings-2020).

Debates

Timing of intervention in unilateral paralysis

Because some unilateral paralyses recover spontaneously as the nerve heals while others do not, there is ongoing discussion about how long to observe before offering procedures to improve glottic closure, balancing the chance of recovery against persistent voice and swallowing impairment.

Seminal works

• benninger-1998

Frequently asked questions

Why can bilateral vocal fold paralysis threaten the airway while voice is preserved?

When both folds are paralyzed they often rest close to the midline. That position can keep the voice relatively normal because the folds still approximate for sound, but it leaves only a narrow opening for breathing, which can compromise the airway.

Is vocal fold paralysis the same as the joint being fixed?

No. Paralysis is loss of movement due to a nerve problem, whereas cricoarytenoid joint fixation is mechanical immobility of the joint with intact nerves. They can look similar on examination, so distinguishing them is part of the evaluation.