Disease of the Pharynx and Larynx

What is the normal anatomy of the pharynx?

• soft palate separates nasophaynx and oropharynx

• larynx sits in nasopharynx

• pharynx packs rigid support by bone / cartilage - may collapse during exercise (when there’s increase in negative pressure)

what is the function of the pharynx?

• passage of air - nasal cavity to larynx and lower airways

• passage of invests - oral cavity to oesophagus during swallowing

How does the pharynx help in airway protection?

• arytenoid closure

• vocal cord closure

• epiglottis retroversion

what is the anatomy of the pharynx?

• muscular tube

• reliant on neuromuscular function for stability

• has intrinsic and extrinsic musculature

• *innervation

what is the main function of the larynx?

1. breathing

2. protect lower airway

3. vocalisation

what cartilage structure is there in the larynx?

1. cricoid cartilage

2. thyroid cartilage

3. epiglottis

4. paired arytenoid cartilages

what processes are there on the arytenoid cartilages?

• muscular process

labelled diagram

what is involved in abduction of larynx?

• opening of the glottis - in exercise

• cricoarytenoideus dorsalis (CAD) muscle

what is involved in adduction of larynx?

what are clinical signs of larynx and pharynx disease?

what would we do during clinical examination if we suspect larynx or pharynx disease?

• palpitation of larynx

• muscular process of arytenoid

• cricothyroid articulation

• observation during exercise

• listen

• inspiratory / expiratory noise

• horses breathing is coupled with gait at canter - should breathe in when front legs come up

How should we diagnose larynx and pharynx disease?

• use endoscopy first

• at rest - can’t only problems that occur during exercise

• at exercise - can be done on treadmill

What other diagnostic imaging can be done for larynx and pharynx disease?

• ultrasonography useful

• radiography not as useful

what are clinical signs of disorders of the pharynx?

• poor performance

• respiratory noise

what are the main disorders of the pharynx?

what are the types of dorsal displacement of the soft palate (DDSP)?

• intermittent DDSP

• persistent DDSP

what is intermittent DDSP?

• dynamic condition - during intense exercise only

• soft palate displaces

what is persistent DDSP?

photos of DDSP

what is the proposed pathogenesis of intermittent DDSP?

how do we diagnose DDSP?

how do we treat DDSP conservatively?

• change tack - keep mouth closed

• tongue tie - stop caudal movement of tongue

• treat inflammatory conditions

• get horses fit - train respiratory muscles supporting pharynx

• maturity - common in younger horses

• throat support device e.g. Cornell collar - but can’t wear during races

How can we surgically treat DDSP?

• tie forward - laryngeal advancement procedure

• Palatoplasty - thermal / laser cautery, stiffens soft palate through scar tissue, although poor evidence for efficacy

What is pharyngeal lymphoid hyperplasia (PLH)?

• enlargement of lymphoid follicles on the walls of nasopharynx

when do we see nasopharyngeal collapse?

• nasopharyngeal dysfunction - can occur in neonates and self resolves

• dynamic pharyngeal collapse

what can cleft palate cause in horses?

what are differential diagnoses for cleft palate?

how do we diagnose cleft palate?

what are the main disorders of the larynx?

what are clinical signs of disorders of larynx?

what is recurrent laryngeal neuropathy (RLN)?

left unilateral paresis / paralysis of …

(left side affected in 95% cases)

what is the pathophysiology of RLN?

what is the likely cause of RLN?

• cause unknown

• likely genetic aetiology

• seen in large horses

• very common in Thoroughbred and draught horses

How do we diagnose RLN?

• history - abnormal noise exercise (inspiratory noise - roaring)

• endoscopy at rest and exercise

• laryngeal ultrasound

what do we assess during endoscopy with suspected RLN?

arytenoid cartilages for:

• symmetry

• synchrony

• maintenance of abduction

how do we grade RLN with endoscopy?

Havermeyer system most common

• graded 1-4 at rest

• graded A-D at exercise

what are surgical management options for RLN?

• prosthetic laryngoplasty

• ventriculo-cordectomy

• laryngeal re-innervation - nerve graft

How do we perform a prosthetic laryngoplasty (tie back) for RLN?

what are potential complications for prosthetic laryngoplasty?

• coughing

• seroma formation

• infection of implant

• dysphagia

what is vocalcordectomt?

removal of left ± right vocal cord

what is ventriculocordectomy?

what is laryngeal re-innervation?

• reinnervation of CAD

• implanting nerve / muscle pedicle grafts from the omohyoideus muscle into affected CAD

• new technique - C1/C2 nerve is implanted directly into affected CAD

what are differential diagnoses for unilateral laryngeal paralysis?

• due to perivascular injection

• guttural pouch mycosis

• previous surgery on guttural pouch or cervical region

what are differential diagnoses for bilateral

what is epiglottic entrapment?

• loose subepiglottic tissue wraps over and entraps epiglottic cartilage

• can be intermittent or persistent

• prevents epiglottic function

what are clinical signs of epiglottic entrapment?

how do we diagnose and treat epiglottic entrapment?

what are sub-epiglottic cysts?

what are clinical signs of subepiglottic cysts?

how do we diagnose and treat

what is arytenoid chondritis?

what are clinical signs of arytenoid chondritis?

how do we diagnose and treat arytenoid chondritis?