Vocal Cord Paralysis

Anatomy & Innervation - Nerve Nuances

• Larynx: Cartilages: Thyroid, Cricoid, Arytenoids.
• Intrinsic Muscles:
  • Abductor: Posterior Cricoarytenoid (PCA).
  • Adductors: LCA, Interarytenoid (IA).
  • Tensors: Cricothyroid (CT), Thyroarytenoid (TA).
• Nerve Supply (Vagus CN X):
  • SLN: Ext. br. to CT (tensor, 📌 CT Sings!); Int. br. sensory (supraglottis).
  • RLN: Motor (other intrinsics); Sensory (infraglottis).
    • Course: Left loops aortic arch; Right loops subclavian artery.

    ⭐ Left RLN is longer and more vulnerable.

• Semon's Law: RLN palsy → PCA (abductor) paralysis predominates. Cord: paramedian.

Etiology & Pathophysiology - Cause & Chaos

• Categories: Neoplastic; Surgical (iatrogenic); Neurological; Inflammatory/Infectious; Idiopathic.
• Pathophysiology: Injury to Vagus (CN X) or its branch, the Recurrent Laryngeal Nerve (RLN), leads to impaired vocal fold adduction/abduction. Nerve damage ranges from neuropraxia (temporary) to neurotmesis (severance).

Common Causes & Nerve Affected:

⭐ Malignancy (e.g., lung, esophageal) is a key consideration in older patients presenting with idiopathic unilateral vocal cord paralysis, especially left-sided due to the longer course of the left RLN.

Clinical Features & Diagnosis - Symptoms & Scopes

• Key Symptoms:
  • Hoarseness: Breathy voice (dysphonia), often the primary complaint.
  • Biphasic Stridor: Inspiratory & expiratory noise, indicates severe airway narrowing (esp. bilateral).
  • Aspiration: Coughing/choking during swallowing, esp. liquids.
  • Dysphagia: Difficulty swallowing.

*   **Indirect Laryngoscopy (IDL)**: Initial OPD screen.
*   **Flexible Nasopharyngolaryngoscopy (NPL)**: Gold standard for dynamic assessment of cord mobility.
*   **Videostroboscopy**: Evaluates mucosal wave; differentiates paralysis from fixation, assesses glottic closure.
*   **Laryngeal EMG (LEMG)**: Confirms neurogenic paralysis, differentiates from cricoarytenoid joint fixation; aids prognosis.
*   **Imaging (CT/MRI Neck & Chest)**: Crucial to find underlying cause (e.g., tumors along vagus nerve path from skull base to thorax).

⭐ Bilateral abductor paralysis (cords in median position) is a respiratory emergency requiring immediate airway management.

Management & Complications - Treatment Tactics

1. Conservative Management:

• "Wait and watch" for 6-12 months for potential spontaneous recovery.
• Voice therapy with a speech and language pathologist (SLP).

2. Medical Management: Address underlying etiology (e.g., treat myasthenia gravis, infection, inflammation).

3. Surgical Interventions:

• Unilateral Vocal Cord Paralysis (UVCP) - Aim: Improve Voice Quality:
  • Medialization Procedures (pushing cord medially):
    • Injection Laryngoplasty: Temporary augmentation (e.g., Gelfoam, autologous fat, CaHA, hyaluronic acid).
    • Thyroplasty Type I (Isshiki): Permanent medialization framework surgery.

⭐ Isshiki Thyroplasty Type I is the gold standard for permanent medialization in unilateral vocal cord paralysis.

• Bilateral Vocal Cord Paralysis (BVCP) - Aim: Ensure Adequate Airway:
  • Emergency (Acute Stridor): Tracheostomy is paramount to secure airway.
  • Lateralization Procedures (widening glottis): E.g., posterior cordotomy, arytenoidectomy.
• Reinnervation: E.g., ansa cervicalis to recurrent laryngeal nerve (RLN) anastomosis; variable success.

4. Complications:

• Aspiration (risk of pneumonia).
• Airway obstruction / Dyspnea (especially in BVCP).
• Persistent dysphonia or aphonia.

High‑Yield Points - ⚡ Biggest Takeaways

• Left RLN palsy is more common; non-laryngeal malignancy (e.g., lung cancer) is a key cause.
• Thyroidectomy is the most frequent iatrogenic cause of RLN injury.
• Hoarseness is the hallmark symptom; bilateral abductor palsy leads to stridor.
• Paramedian position indicates RLN palsy; cadaveric suggests complete paralysis (RLN + SLN).
• Laryngoscopy is diagnostic; CT scan (skull base to chest) is vital for etiology.
• Semon's Law: Abductor fibers are affected before adductors in progressive lesions.