Physiology of voice and hoarseness

1. Physiology of voice and hoarseness Michael J. Odell BSc MD FRCSCAssistant Professor Department of Otolaryngology – Head and Neck Surgery University of Ottawa

2. Objectives • -Explain how the lungs, larynx and upper airway all contribute to voice. • -Describe the nerve supply to the larynx and explain the movement of the vocal cords during phonation and respiration. • -Describe the role of the larynx in phonation, swallowing and respiration and recognize the impact of pathology of the larynx may have in any of those processes.  

3. Objectives • -Explain how a vocal cord nodule develops. • -Define the symptoms of laryngeal disease including: hoarseness, odynophagia, dysphagia and stridor. • -Provide a differential diagnosis for the patient presenting with hoarseness.

4. Production of voice • Lungs • Larynx • Upper airway

5. The production of voice • Lungs • Needed to produce exhaled air to power the voice • Strength of voice can be dependent on lung capacity

6. The production of voice • Larynx • Phonation – the generation of sound by vibration of the vocal cords • Requires vocal cords with vibratory capacity and appropriate position of vocal cords (adduction) • Pitch can be modulated by movement of laryngeal muscles

7. The production of voice • Upper airway (tongue, lips, pharynx) • Articulation – shaping sounds into words • Resonance – induction of vibration to modulate laryngeal input

8. Anatomy of larynx

9. Anatomy of larynx

10. Anatomy of larynx

11. Laryngeal nerves • Superior laryngeal nerve • Branch of vagus • Goes through thyrohyoid membrane to reach larynx • Sensory to supraglottic larynx • Innervates cricothyroid muscle

12. Laryngeal nerves • Recurrent laryngeal nerve • Branch of vagus • Descends into chest • Left side – loops around ductus arteriorosis • Right side – loops around subclavian artery • Ascends in tracheo-esophageal groove to pierce cricothyroid membrane and enter larynx • Sensory to glottis and infraglottic larynx • Motor to all laryngeal muscles except cricothyroid muscle

14. Role of larynx • Phonation • Deglutition • Respiration

15. Movement of vocal cords during phonation/respiration

16. Respiration --- Phonation

17. Tension of vocal cords determines pitch • As the vocal cords adduct, air is forced through from the lungs below which vibrates them and produces voice • The amount of tension of the vocal cords affects the pitch (or frequency) of that voice

18. Intrinsic muscles of larynx • Cricothyroid (SLN) • Interarytenoid (RLN) • Posterior cricoarytenoid (RLN) • Lateral cricoarytenoid (RLN) • Thyroarytenoid (vocalis) muscle (RLN)

20. Symptoms of laryngeal disease • Hoarseness • Intermittent or constant • Different characteristics of hoarseness • Breathy • “Raspy” • “Hot potato” • Laryngeal masses will cause hoarseness when very small – therefore are usually detected early

21. Symptoms of laryngeal disease • Airway obstruction • Stridor • Shortness of breath (especially with exertion) • Should be a very LATE finding

22. Symptoms of laryngeal disease • Dysphagia • Mass may be large enough to block upper esophagus • Aspiration • If protective function of larynx during swallowing is lost, may result in aspiration into lungs • Aspiration pneumonia

23. Differential diagnosis for hoarseness

24. Normal larynx

25. Laryngeal cancer • Usually squamous cell carcinoma • Risk factors: • Smoking • Alcohol (may have synergistic effect with smoking) • Early sign: Hoarseness • Late signs: Neck mass, airway obstruction, aspiration, dysphagia • Treatment: surgery vs. radiation therapy

26. Larynx cancer

27. Larynx cancer

28. Laryngeal papillomatosis • Benign lesions caused by HPV • Can cause significant hoarseness, if left unattended -> airway obstruction • Can be seen in infancy (juvenile papillomatosis) or adulthood • Treated by surgical removal – tend to recur

29. Laryngeal papillomatosis

30. Vocal cord paralysis • Unilateral • One cord remains fixed just lateral to midline • Cords are unable to adduct fully – leaves gap • Breathy voice, aspiration • Treatment: injection of cord with collagen • Bilateral • Both cords fixed just off midline • Too small an airway to breathe – AWO • Treatment: tracheostomy

31. Unilateral vocal cord paralysis • tumor growth into RLN (mediastinal tumors, thyroid tumors, metastatic breast cancer) • iatrogenic trauma to RLN (thyroid surgery, cardiac surgery) • Idiopathic

32. Bilateral vocal cord paralysis • Usual causes: neurological • Stroke • Guillain-Barre syndrome • Idiopathic • Iatrogenic • Surgery • Thyroid, esophagus

33. Unilateral vocal cord paralysis

34. Laryngeal nodules • Overuse/abuse of the voice will cause strain on the vocal cords • Over time a small nodule will develop • Often bilateral • Kids: “screamer’s nodules” – bilateral nodules at junction of anterior 1/3 and posterior 2/3 of vocal cord • Adults: may be same or unilateral

35. Laryngeal nodules • If removed surgically, but underlying cause of voice abuse is not dealt with, will quickly recur • Treatment: speech therapy (relearn appropriate vocal habits, avoid screaming, use voice less occupationally) -> often results in resolution

36. Laryngeal nodules - unilateral

37. “Screamer’s nodules”

38. Granulomas of larynx • Trauma to the vocal cord can result in the development of a granuloma (abnormal tissue occurring as a result of healing) • Common scenario: intubation granuloma

39. Intubation granulomas

40. Reinke’s edema • Collection of fluid in Reinke’s space (loose connective tissue layer of true vocal cord) • Results in floppy, swollen, edematous vocal cords • Usually caused by smoking • Can often resolve if quit smoking, or can be treated surgically

41. Reinke’s edema

42. GERD • Probably the most common cause of hoarseness seen in ENT clinic • Mostly happens at night while patient supine • 60% of patients with Laryngeal GERD are unaware of GERD symptoms • Usually hoarseness is intermittent (often worse first thing in the morning)

43. GERD • Signs: erythema and edema of mucosa of posterior glottis on endoscopy (esophagus is posterior to glottis and reflux affects that portion of glottis primarily) • Treatment: PPIs

44. GERD

45. Vocal cord hematoma • Trauma to anterior larynx can cause compression of laryngeal cartilages and result in vocal cord hematoma • Acute hoarseness after traumatic incident • Usually resolves spontaneously • CT important to rule out laryngeal fracture (may require ORIF)

46. Vocal cord hematoma

47. Spasmodic dysphonia • Condition where excessive muscle tension in laryngeal muscles causes strangulation of voice • Very short phonation times, very difficult to create voice • Treatment: BOTOX (very effective, needs to be repeated q6 months)

48. Other neurological conditions • Amyotrophic lateral sclerosis (ALS) • 25% of patients initially present with speech problems • Parkinson’s disease • Decreased loudness, monopitch, poor articulation of sounds • Myasthenia gravis • Fatigue of laryngeal muscles when asked to make repetitive sounds

49. Conclusions • Larynx has critical role in • Phonation • Deglutition • Respiration • Recurrent laryngeal nerve anatomy allows understanding of causes of vocal cord paralysis

50. Conclusions • Wide range of differential diagnoses for hoarseness • Persistent hoarseness needs to be examined by Otolaryngologist • Need to rule out laryngeal cancer