Section 4


What is the diagnosis?

Right vocal cord palsy/paresis

Name three possible causes for this

  • Congenital
  • Idiopathic
  • Iatrogenic e.g. during surgery damage to recurrent laryngeal nerve
  • Neck or chest injury
  • Tumours affecting nerve or causing compression
  • Infections e.g. Lyme disease, herpes
  • Rheumatological
  • Neurological problems e.g. multiple sclerosis, myasthenia gravis, stroke

What investigation would you request to investigate possible cause?

CT skull  base to diaphragm

What is Semon’s law?

In a progressive lesion of the recurrent laryngeal nerve, the abductors are paralysed before the adductors. Therefore incomplete paralysis of the vocal cord results in the vocal cord being brought to the midline, but in complete paralysis the cord will be in the paramedian position.

Describe two symptoms the patient may complain of

  • Hoarseness
  • Stridor
  • Breathy quality to voice
  • Unable to project voice
  • Inefficient coughing
  • Aspiration

If no cause is found, describe three options to improve their symptoms.

  • Speech and language – voice therapy
  • Surgery to medialise the affected vocal cord
    • Bulk injection e.g. bioplastique, collagen, fat
    • Thyroplasty

Supporting Information

Anatomy of the larynx

The skeleton of the larynx consists of the laryngeal cartilages which calcify during puberty:

  • Hyaline– thyroid, cricoid and arytenoid, corniculate, cuneiform
  • Fibrocartilage– epiglottis 
  • Fibroelastic accessory cartilage  

The larynx is split into 3 parts:

  1. Supraglottis- laryngeal surface epiglottis, aryepiglottic folds, vestibular folds, laryngeal ventricles as the superior surface vocal folds. 
  2. Glottis- vocal folds and 1cm inferior
  3. Subglottis– down to lower border cricoid

Vocal cord layers (superficial to deep):

  • stratified squamous epithelium
  • Reinke’s space (superficial lamina propria)
  • Vocal ligament (intermediate and deep lamina propria)
  • Thyroarytenoid/vocalis muscle

Muscles of the larynx- controlled by internal and one external muscle (cricothyroid)

Action

Muscles

Cord abduction

Posterior crico-arytenoid

Cord adduction

Lateral cricoarytenoid muscle
Transverse arytenoid muscle
Oblique arytenoid

Vocal cord tension

Cricothyroid
Thyroarytenoid

Nerve supply of the larynx

This is by the vagus nerve (CN X) – splits into:

  • Superior laryngeal nerve- 
    1. Internal branch- sensory- supraglottis and superior aspect vocal cords 
    2. External branch- motor- cricothyroid muscle
  1. Recurrent laryngeal nerve- left one loops around the arch of the aorta and travels in the tracheoesophageal groove. Right one loops under the right subclavian and into the tracheoesophageal groove. Both enter at the inferior cornu of the thyroid cartilage. 
    1. Sensation to larynx inferior to glottis and inferior aspect of vocal cords
    2. Motor to all other laryngeal muscles

Arteries and the relations to the nerves:

  • Superior thyroid- external carotid- enters at the superior pole of thyroid. Early in path it lies close to superior laryngeal nerve
  • Inferior thyroid artery – thyrocervical trunk- bends medial at C6 and enters lower thyroid pole. Both sides lie close to the recurrent nerve. 
    • RLN anterior to artery- 25%
    • RLN posterior to artery – 35%
    • RLN between branches of artery- 35%

Vocal cord palsy- unilateral or bilateral

  • Causes: 
    • Iatrogenic- cardiac surgery, endarterectomy, thyroid surgery
    • Malignancy- lung and thyroid
    • Traumatic
    • Viral 
    • Idiopathic
  • Symptoms- hoarseness, inadequate voice projection, breathy voice, dysphagia
  • Investigations– CT skull base to mediastinum, CXR, microlaryngoscopy
  • Treatment- 
    • Conservative to check for resolution with voice rehab
    • Medical – botox
    • Surgical medialisation of vocal cord but wait for 6 months for contralateral cord compensation and resolution of a possible viral cause. 
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