ENT (Otorhinolaryngology) · MU Sofia

34. Types of paralysis of the larynx.

Covers the definition of laryngeal paralysis and how it arises, including nerve injury, the longer left recurrent laryngeal nerve course, and causes ranging from thyroid surgery and tumours to neurological disease. It then sets out unilateral, bilateral, superior laryngeal and combined types in a summary table, followed by clinical features, investigations such as laryngoscopy and electromyography, treatment options, complications and differential diagnoses.

Inside: 1 section · 1 table · 15 flashcards · 4 min

Topic 34 of 52 in the MU Sofia syllabus for ENT (Otorhinolaryngology) (Medicine, Year 4). The free AceMed note covers it in 1 section, about 562 words (4 min of reading), with 15 flashcards.

In this note

  1. Types of paralysis of the larynx.

Types of paralysis of the larynx.

1. Definition: Laryngeal paralysis is the complete or partial failure of the vocal folds to abduct (open) or adduct (close) due to a impaired function of the recurrent laryngeal nerve (RLN)- all intrinsic except cricothyroid, superior laryngeal nerve (SLN), or intrinsic laryngeal muscles.This results in functional deficits in breathing, phonation (voice), and airway protection (swallowing).

2. Etiopathogenesis

The pathogenesis usually involves damage to the Recurrent Laryngeal Nerve (RLN) or the Superior Laryngeal Nerve (SLN).

  • Neural Injury: Compression, traction, or transection of the nerve.
  • Anatomical Vulnerability: The left RLN has a longer course, looping under the aortic arch, making it more susceptible to thoracic pathologies than the right RLN, which loops under the subclavian artery.
  • Muscular Atrophy: Denervation leads to atrophy of the posterior cricoarytenoid muscle (the only abductor), causing the vocal fold to remain in a paramedian or midline position.
  • Iatrogenic (most common): Thyroidectomy (RLN injury is classic), Parathyroid surgery
  • Tumors: Thyroid carcinoma, Lung cancer (especially left RLN involvement around the aortic arch)
  • Neurologic / central causes: Stroke, ALS, Multiple sclerosis, Parkinson’s disease

3. Classification

4. Clinical Picture

A. Unilateral Vocal Fold Paralysis (UVFP)

  • Symptoms: Hoarseness, breathy voice, Reduced vocal intensity, Dysphagia, aspiration especially liquids, Usually no severe dyspnea
  • Signs (on laryngoscopy): Abductor paralysis = median or paramedian position- most common vocal cord position., Adductor paralysis = intermediate position with glottis gap
  • Symptoms usually improve within 6 months due to compensation of other mobile vocal cord, which crosses the midline during phonation to meet paralysed cord

B. Bilateral Vocal Fold Paralysis (BVFP)

  • Symptoms: Severe dyspnea, stridor on inspiration, Normal or near-normal voice, Cyanosis, or agitation. Life-threatening airway obstruction.
  • Signs: Both cords fixed in midline position, Narrow glottic airway.

C. Superior Laryngeal Nerve Paralysis

  • Symptoms: Weak, monotonous voice, Loss of high-pitch phonation, Aspiration (due to loss of supraglottic sensation)
  • Signs: Ipsilateral cricothyroid muscle paralysis, Asymmetrical pitch elevation, Bowing of the true vocal fold.VC appear normal at rest.- laryngoscopy

5. Paraclinical and Radiological Examinations

  • Flexible Laryngoscopy: The gold standard for direct visualization of vocal fold movement and glottic gap.
  • Laryngeal Electromyography (LEMG): Distinguishes between nerve paralysis and mechanical fixation; helps determine prognosis (reinnervation vs degeneration).
  • Radiology (CT/MRI): A "skull base to thoracic inlet" scan is mandatory to rule out tumors along the course of the Vagus/RLN.

6. Treatment Options

  • Conservative: Voice therapy (speech-language pathology) to help the healthy fold compensate.
  • Surgical (Unilateral): Aimed at improving voice (Medialization).

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