29. Larynx and trachea Flashcards
LABEL THE CARTILAGES!
How many layrngeal cartilages are there?
What is the mnemonic for hyoid bones?
8!
- Epiglottis, arytenoid x2, thyroid, cricoid, interarytenoid, sesamoid
- “SOME ELEPHANTS CAN BE TREATED”
What structures divide the different pharyngeal components?
- Soft palate: seperates oro/naso
- Palatopharyngeal arches: Band extending caudodorsal from soft palate, separates naso/layrngo
- Epiglottis: Seperates oro/layrngo
Where is the piriform recess?
Cauddorsal aspect of layrngopharynx
Name the processes of the arytenoid cartilages. How many are there?
4!
Cuneform: Most rostral, may be visualised rx in large dogs
Corniculate
Muscular
Vocal
Which layrngeal cartilage is typicall most visualised when mineralisaed?
Cricoid
What are the most common tumours of the canine pharynx and layrnx?
What are the most common tumours of the feline layrngopharynx?
Dog:
Larynx: epithelial tumours and rhabdomyoma/sarcoma MOST COMMON -> also MCT, sarcomas, oncocytomas, plasma cell, melanoma
Pharynx: SCC (particularly tonsillar)
Cats: Lymphoma and SCC
DDX PHARYNGOLARYNGEAL MASS BOX
Which bone of the hyoid has a specific neoplastic syndrome associated with it?
Basihyoid - site of ectopic thyroid carcinoma -> strongly vascularised, heterogeneous masses with mineralised foci
=> result in severe lysis of basihyoid and infiltration of laryngeal wall
What % of acute oropharyngeal stick injuries develop emphysema?
83%
What is a significant consideration when hyoid fracture is observed?
- Potentially open to respiratory tract -> may be contaminated
What radiographic features are used to characterise soft palate thickening and elongation in BOAS?
- Extension of the soft palate caudal to tip of epiglottis
- Narrowing of oropharyngeal / nasopharyngeal diameters
Why is layrngeal collapse infrequently documented radiographically?
Occure in laterolateral direction. May be seen if severe
Which breed has a specific upper airway obstructive syndrome described?
NORWICH TERRIERS
- Supra-arytenoid swelling and laryngeal narrowing often at ventral region of thyroid cartilage
Features of epiglottic retroversion
- RARE - excessive epiglottic mobility, with caudal retroflexion into rima glottidis
- 80% SECONDARY TO OTHER CONDITIONS: BOAS, tracheal collapse, LarPar, epiglottic fracture, malacia, peripheral neuropathy
- Rx: More vertically positioned epiglottis, extending dorsally to dorsal wall of layrngopharynx.
Features of pharyngeal collapse
- Complete / partial dorsal displacement of soft palate OR ventral displacement of dorsal pharyngeal wall
- Fluro useful as often dynamic
- Often other resp conditions e.g. trach/bronch collapse, BOAS
Features of nasopharyngeal stenosis
- Uncommon, typically cats
- Commonly thought to be ACQUIRED: infection/inflam, sx
- HOWEVER Congenital type in Dachsunds -> Palatopharyngeal dysgensis leading to thickening of muscles, seperates/obliterates nasopharynx
Tracheal deviation BOX
Also, remember TO THE LEFT with Persisitent right 4th aortic arch
List DDx for tracheal tumours - benign and malignant
Tracheal masses normally neoplastic!
- Benign (dogs):
Osteochondroma (normally young dogs}
Chondroma
Leiomyoma
Malig :
- Round cell: Lymphoma, Histiocytic, plasmacytoma
- Sarcoma: FSA, CSA,
- Carcinoma: ADC, SCC
Which parasites are associated with tracheal granuloma formation?
Oslerus osleri:
- DOG
- Mass near carina
Cuterebra:
- CAT
Rx features of tracheal rupture
- Pneumomediastinum, emphysema,
- Less commonly: intratracheal fluid, mural haematoma, stenosis
=> SITE OF RUPTURE MAY BE HARD TO DETECT
Features of tracheal avulsion
- Often blunt trauma with head extended
- May present 1-3 weeks post, with resolution of mediastinal / ST gas
=> Rx: circumferential tracheal discontinuity 1-4cm cranial to carina, and PSEUDOAIRWAY -> dilation of lumen with thin margin
NB: Bronchial avulsion also reported
What % of BOAS dogs have trachceal hypoplasia?
39%
In 10% dogs, incidental finding
Describe the reported tracheal:thoracic inlet ratios published for different dog breeds (and also cats)
Non-brachys: 20%
Non-bulldog brachys +- BOAS signs: 16%
Bulldogs: 13%
=> Smalles ration in asymptomatic bulldogs was 9%
On CT:
26% reported in asympt / grade 1 english bulldogs
CATS: DSH 18%, persians 20%
Which ratios have been desribed for evaluating tracheal diameter?
Trachea: thoracic inlet (see other q)
Trachea: cricoid -> smaller in brachys
