11. Nasal cavity Flashcards
What are the three different skull types?
Brachycephalic: Short, wide
Mesaticephalic: Medium length
Dolichocephalic: Longer nose.
Describe three key anatomical areas of interest for the occipital bone
1) Occipital crest - most dorsocaudal aspect of skull
2) Forms base of skull!
3) Occipital condyles -> caudoventral, surround foramen magnum
Describe features of the vomer bone
UNPAIRED
Forms caudoventral aspect of nasal septum
Name three sinuses / recesses of skull (both dogs and cats)
Frontal
Maxially (recess)
Sphenoidal (small)
The tympanic bullae are part of which bone?
Temporal
Name three portions of the temporal bone
Petrous: Medial and dorsal to bullae -> DENSE
Squamous -> Extends rostrally and laterally to form zygomatic arch (ZYGOMATIC PROCESS)
Tympanic: Bullae!
What type of joint is the TMJ?
Condylar
Temporal part = zygomatic process of squamous temporal bone (forms mandibular fossa and retroarticular process)
Mandibular part = condyloid process -> articulates with mandibular fossa
List 4 radiographic signs of hydrocephalus
Doming of calvarium,
Open fontanelle,
Homogeneous appearance (loss of convolutional markings of skull)
Cortical thinning.
How does occipital dysplasia look? Which breeds?
Dorsal extension of the foramen magnum.
Miniature and toy breeds. May be normal variant in brachys.
Describe pathophysiology of “Chiari-like malformation”
HEREDITARY - malformation of occipital bone -> Overcrowding of caudal fossa, obstructed CSF flow -> Syrinx and hydrocephalus.
CKCS, other brachys
*Larger syrinx more likely to be clinically affected*
* Foramen magnum size correlates with size and length of cerebellar herniation*
Localises to central spinal lesion, phantom scratching.
Which breeds are predisposed to open mouth jaw locking / asymptomaitc TMJ dysplasia?
Bassets and Irish setters -> symptomatic. Condyloid process moves lateral to zygomatic process, tends to become physically entrapped on side CONTRALATERAL to worst changes.
Spaniels, pekingnese and dachs -> Asymptomatic anatomical variant of TMJ dysplasia
What is Mucopolysaccharidosis?? Which breeds are affected? WHat are the radiographic features?
MPS VI - AUTOSOMAL RECESSIVE in SIAMESE!
- Lysosomal storage disease
- Rx: Epiphyseal dysplasia, osteporosis, pectus excavatum, head (shortened nasal conchae, aplasia / hypo of sphenoid and frontal sinuses; shortened incisive and maxillary bones), and spinal changes
MPS 1 - documented in DSH
- SImilar, but facial dysmorphia may not be as pronounced
Hyperparathyroidism! Basic pathophys, primary vs secondary types / causes.
Inc PTH -> hypercalcaemia, and bone resorption
PRIMARY: Adenoma, adenocarcinoma, hyperplasia
SECONDARY: nutritional, renal-> non-endocrine alterations in ca and phos homeostasis
Rx: LOSS OF LAMINA DURA (early sign), osteolysis and osteomalacia (demineralisation of skull)
=> Severity depends on duration. Also young animals more affected due to rapid bone turnover
- WHEN EXTREME -> Replacement by fibrous tissue (Fibrous osteodystrophy) -> skull thickening
US features of primary hyperpara
3-23mm mass in +++ dogs (129/130 in study)
Also, 31% cystic calculi -> All calcium phos or ox
What are the most common nasal tumours in dogs / cats?
2/3rds = epithelial -> Adenocarcinoma, SCC, undifferentiated carcinoma
1/3rd = mesenchymal -> FSA / CSA / OSA
- IN CATS, also lymphoma prevalent
Rx of nasal tumours
Which features are associated with worse px?
Lysis of conchae, inc opacity of nasal cavity…. May be uni or bilateral
ALSO!! Look for lysis of adjacent bones, increased opacity of frontal sinuses (tumour extension vs occlusion of drainage)
Look for cribriform plate lysis, bony destruction -> worse px
Which rx views are best for assessment of nasal tumours?
Intraoral DV -> best as caudal placement of plate better allows for evaluation crib plate
Openmouth VD
+- rostrocaudal frontal sinus projection
On CT, what features are considered hallmark of nasal neoplasia?
MASS EFFECT and lysis
=> Mass effect, no lysis - more typical of infection
=> Lysis no mass effect - fungal rhiniits
What are the common mandibular and maxillary tumours of the dog and cat?
SCC - both
Fibrosarcoma, Melanoma - DOG
Features of canine SCC?
Features of canine FSA?
Features of canine oral melanoma?
SCC:
- Rostral mandibular location
- Lysis, with rare mets.
- 82% with bone involvement
FSA:
- Large breeds, particularly GRet
- max and mand, but PALATE predilection
- 78% with bone involvement
Melanoma:
- All sized dogs!
- Frequent nodal and pulmonary mets
- Variable lysis
Mutilobulated osteochondrosarcoma (MLO)! Features
- older large dogs,
- Temporo-occipital region typically, but also reported: zygomatic, tympanic, orbit, max, mand, hard palate.
- Well-defined, granular (popcorn) appearance, lysis of adjacent bone
Skull OSA! How common? Where? Rx?
Osteoma. How different?
- 10-15% of canine OSA occur from skull
- Max (43.7%) > Mand (32.8%) > calvarium (23.5%)
- If cranial vault, more well-defined than appendicular or other skull site -> OSTEOBLASTIC. Contain granular areas of calcification.
Osteoma - slow growing, benign. No lysis.
Nasal aspergillosis! Features:
Non-brachy, young (<4) dogs
- Primarily A. fumigatus
- Rx: Lysis of conchae with punctate lucencies, inc ST of cavity, +- frontal sinus involvement (opacity +- mottled bony thickening). In advanced disease, nasal septum erosion or deviation.
Feline nasal fungal disease! Which spp.?
- CRYPTOCOCCUS NEOFORMANS (more common in cats) -> non-destructive hyperplastic rhinitis
- Also: Asper, hyalohypohmycosis
