Ch 99 - Nasal planum, nasal cavity and sinuses

Question 1

What ligaments support the cartilages of the external nose?

Answer 1

• Dorsal nasal ligament
• Paired lateral nasal ligaments

Question 2

What muscles allow for movement of the external nose?

Answer 2

• Levator nasolabialis
• Orbicularis oris
• Levator labii maxillaries
• Frontalis

Question 3

List the air passages of the nose

Answer 3

Dorsal, middle, ventral and common meatus

Question 4

List the three paranasal sinuses

Answer 4

• Maxillary recess
• Sphenoidal sinus
• Frontal sinus - connected to nasal fossa via nasofrontal opening, through which an ethmoidal turbinate extends

Question 5

What are the bony walls of the rostral nasopharynx (choanae)

Answer 5

• Hard palate ventrally
• Vomer bone dorsally
• Palatine bone laterally

Question 6

What is the mechanism of transmission of scent?

Answer 6

• Odorant substances bind to receptor proteins on surface of cilia arising from olfactory cells
• G-protein coupled transmembrane protein mechanism causes transmembrane Na-channel opening and influx of intracellular Na
• Creates an action potention in olfactory nerves

Question 7

What parts of the brain react to scent?

Answer 7

• Olfactory bulb
• Cadate nucleus activity when scent is associated with a positive or rewards in stimuli such as the owner

Question 8

What make the nose moist?
How does this contribute to defensive mechanisms?

Answer 8

• Paired lateral nasal glands
• Secretions contain immunoglobulin A

Question 9

What are the top 2 DDx for intranasal mass lesions on advanced imaging?

Answer 9

• Neoplasia
• Fungal rhinitis (characteristic cavitary appearance)

Question 10

What anatomical features of the nasal cavity may be normal in cats but can often be mistaken for pathological?

Answer 10

• Deviation of the septum
• Sinus asymmetry
• Significance of septal lysis or cribiform lysis is predictive of neoplasia in dogs but the significance of these findings in cats is debated

Question 11

How does the diagnostic accuracy of blind nasal biopsy compare with rhinoscopic?

Answer 11

Not significantly different

Question 12

What breeds are predisposed to hereditary nasal parakeratosis and idiopathic depigmentation or vitiligo?

Answer 12

• Hereditary nasal parakeratosis in Labs
• Vitiligo in Rottweilers and Dobermans

Question 13

What is the prognosis with nasal SCC?

Answer 13

Dogs:
- MST 12.5wk with Sx
- MST 26wk with radiation alone
- Recurrence 12/17

Cats:
- MST 12m
- Recurrence 3/8

Question 14

What is stenotic nares?

Answer 14

Axial deviation of the dorsolateral nasal cartilage

Question 15

What breeds are overrepresented with abberant conchae?
What are the common contact points?
What is the Tx option?

Answer 15

• Frenchies and Pugs
• intraconchal and septoconchal
• Diode laser-assisted turbinectomy (regrowth is common but with significantly fewer contact points)

Question 16

What is the most common nasal neoplasia of cats?
What is the MST?

Answer 16

• Lymphoma
• MST 98 days

Question 17

What is the most common nasal neoplasia in dogs?
What is the recommended Tx?
What is associated with a poorer prognosis?

Answer 17

• Carcinoma - locally aggressive
• Radiation is Tx of choice. Cytoreductive surgery does not improve outcome. MST 8-19m
• Involvement of cribiform plate associated with shorter MST 6.7m

Question 18

What nasal cavity disease can predispose to GDV?

Answer 18

Nasal mites - aerophagia

Question 19

What is choanal atresia?
What are the Tx options?

Answer 19

• Congenital condition in which the oronasal membrane fails to resorb. May be partial or complete, osseous or membranous
• Balloon dilatation or open excision and reconstruction

Question 20

What is nasopharyngeal stenosis?
What are the Tx options?

Answer 20

• An acquired condition resulting from nasopharyngeal inflammation resulting in a varibale thick, impenetrable membrance partially or completely occluding the nasopharynx

Tx options:
- Open surgical resection (restenosis has been reported)
- Endoscopic-guided balloon dilatation (membranous and under 5mm thick)
- Stenting (covered for complete stenosis, uncovered for partial)
- Restenosis in up to 35%, oronasal fistula, stent migration

Question 21

What breed is predisposed to congenital stenotic nasopharyngeal dysgenesis

Answer 21

Dachshunds

Question 22

What is the recommended settings when using a CO2 laser for treatment of stenotic nares?

Answer 22

• Power setting 3-5
• 0.4mm fine tip
• Continuous waveform
• Frequent char removal

Question 23

What are the surgical options for stenotic nares?

Answer 23

• Amputation of ventral portion of dorsolateral nasal cartilage (“Traders technique”)
• Lateral, vertical, or horizontal wedge resection
• 2-6mm punch biopsy
• Alapexy

Question 24

What is the reported reduction in airway resistance after laser-assisted turbinectomy?

Answer 24

50% in brachycephalic dogs

Question 25

Why is bilateral temporary carotid occlusion not recommended in cats?

Answer 25

They have a less robust cerebral blood supply and lack of internal carotid artery, increasing the risk of brain ischaemic damage

Question 26

List the approaches to the nasal cavity

Answer 26

• Dorsal (most common for accessing nasal cavity and sinuses)
• Ventral (ventral nasal cavity, nasopharynx, ethmoid turbinates)
• Lateral
• Rostal/alveolar mucosal approach

Question 27

Why is ventral rhinotomy relatively contraindicated in young animals?

Answer 27

Can alter the growth of the muzzle
- Dogs - damage to vomer bone may alter muzzle growth
- Cats - transverse palatal length can be retarded after damage to vomer bone but sagittal length is preserved

Question 28

What complications have been reported after rhinotomy if the cribiform plate is damaged?

Answer 28

• Ventricular pneumocephalus
• Septic meningoencephalitis