Vocal Fold Paralysis

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Basics & Anatomy - Vocal Cord Voyage

  • Vocal folds: True cords for voice. Layers: mucosa, Reinke's space, ligament, muscle.
  • Vagus Nerve (CN X) supplies larynx.
    • Superior Laryngeal N. (SLN): Internal branch (sensory above cords), External branch (motor to cricothyroid - affects pitch).
    • Recurrent Laryngeal N. (RLN): Motor to all other intrinsic laryngeal muscles (abductors & adductors); sensory below cords. Left RLN longer (loops under aortic arch). 📌 SLN Sings (pitch), RLN Roars (voice). Laryngeal Nerves Anatomy: SLN and RLN Branches

⭐ The cricothyroid muscle, supplied by the external branch of the SLN, is the only laryngeal muscle that tenses the vocal cords, thus primarily responsible for pitch elevation.

Etiology - Silent Saboteurs

  • Neoplastic: Lung (Pancoast), thyroid, esophageal, skull base tumors.
  • Iatrogenic: Most common overall. Thyroid/cardiac surgery (RLN injury), intubation, neck dissection.
  • Idiopathic: Diagnosis of exclusion. Viral/inflammatory suspected.
  • Neurological:
    • Peripheral: Diabetic neuropathy, Guillain-Barré syndrome.
    • Central: Stroke (e.g., Wallenberg syndrome), MS, ALS.
  • Trauma: Blunt or penetrating neck injuries.
  • Other: Ortner's syndrome (cardiovocal due to left atrial enlargement).

⭐ Thyroid surgery is the most common iatrogenic cause of unilateral vocal fold paralysis due to Recurrent Laryngeal Nerve (RLN) injury.

Clinical Features - Signs of Silence

  • Voice: Hoarseness, breathiness, diplophonia.
    • UVFP: Weak, airy.
    • BVFP: Variable; near normal (median) to aphonia (cadaveric).
  • Aspiration: Coughing/choking on liquids.
  • Airway:
    • UVFP: Usually normal.
    • BVFP: Stridor, dyspnea (esp. median/paramedian cords).
  • Cord Positions & Impact:
    • Median: Good voice, poor airway.
    • Paramedian: Breathy, airway risk.
    • Cadaveric: Aphonia, aspiration, better airway.

⭐ Bilateral median position: Voice surprisingly good, severe airway compromise_

Diagnosis - Unmasking the Mute

  • Key Investigations:
    • Laryngoscopy (Flexible/Rigid): Initial step. Confirms vocal fold (VF) immobility. Observe position (median, paramedian, cadaveric).
    • Videostroboscopy: Differentiates paralysis from fixation (e.g., cricoarytenoid joint). Assesses mucosal wave, amplitude, symmetry, periodicity.
    • Laryngeal Electromyography (L-EMG): Confirms neurogenic paralysis. Differentiates from mechanical fixation. Prognosticates recovery (detects reinnervation potentials).
    • Imaging (CT with contrast / MRI): Neck & chest (skull base to aorto-pulmonary window). Identifies underlying etiology (e.g., tumors, trauma, inflammation).

Unilateral Vocal Fold Paralysis Diagram

⭐ Laryngeal EMG is the gold standard to differentiate vocal fold paralysis from cricoarytenoid joint fixation and to assess for signs of reinnervation.

Management - Restoring the Voice

  • Voice Therapy: Initial management. Focus on vocal hygiene, compensatory strategies, reducing phonatory effort.
  • Injection Laryngoplasty: Temporary medialization for small-moderate glottic gaps.
    • Materials: Hyaluronic acid, CaHA, autologous fat. Duration: 3-12 months.
  • Thyroplasty Type I (Medialization Laryngoplasty): Gold standard for permanent UVFP.
    • Isshiki Type I: Implant (Silastic, Gore-Tex) via thyroid cartilage window pushes fold medially.
  • Reinnervation: For younger patients, good neuromuscular integrity. E.g., Ansa cervicalis-RLN anastomosis.
  • Arytenoid Procedures: Arytenoid adduction, often combined with Type I thyroplasty for posterior gaps.
  • Airway (Bilateral VFP): If dyspnea, consider tracheostomy, cordotomy, or arytenoidectomy.

⭐ Thyroplasty Type I (Isshiki) is the most common surgical procedure for achieving permanent voice improvement in unilateral vocal fold paralysis.

Thyroplasty Type I Procedure Illustration Awaiting image generation for "Illustration of Thyroplasty Type I procedure steps"...

High‑Yield Points - ⚡ Biggest Takeaways

  • Recurrent Laryngeal Nerve (RLN) injury is the most common cause; left RLN is more vulnerable (e.g., thoracic lesions).
  • Unilateral paralysis presents with hoarseness, breathy voice, and risk of aspiration.
  • Bilateral abductor paralysis is an airway emergency causing inspiratory stridor.
  • Semon's Law: Posterior cricoarytenoid (abductor) muscle fibers are more susceptible to injury.
  • Paramedian position is the most common vocal fold position in unilateral RLN palsy.
  • Thyroplasty Type I (medialization) is a key surgical treatment for symptomatic unilateral paralysis.

Practice Questions: Vocal Fold Paralysis

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Following total thyroidectomy, the patient develops respiratory stridor. The cause is:

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Flashcards: Vocal Fold Paralysis

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Voice becomes breathy in _____ductor dysphonia

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Voice becomes breathy in _____ductor dysphonia

aB

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