1. Chinchilla skull – notice the large bullae!
The Skull
Melanie Eagan
Chinchilla skull – notice the large bullae!

2. Indications for skull rads
Neurological problems
Nasal problems
Mandibular problems
Maxillary problems
1̊ tumors of skull
Mass behind eye
Teeth diseases
Middle ear problems

3. Views Careful positioning is necessary
Sedation or GA usually necessary
Positioning aids to elevate cassette

4. Intraoral dorsoventral view
Good for rostral aspect of nasal cavities

5. Ventrorostral-dorsocaudal oblique
Good for more caudal aspect of nasal cavities
More difficult to assess rostral aspect of nose (shortened by angulation of x-ray beam)

6. Rostrocaudal view
Patient positioning for rostrocaudal rads of frontal sinuses taken with vertical beam

7. Rostrocaudal view Used for viewing frontal sinuses
Rotation of head must be avoided so view is not “obliqued”
Open mouth rostrocaudal used to view tympanic bullae and foramen magnum

8. Lateral oblique used to view:
Tempromandibular joint
Teeth in mandible/maxilla
Fractures in mandible/maxilla

9. differences in the cat skull
Dog skull – left
Cat skull – right
Arrow pointing to cribiform plate
Cats have:
greater doming on frontal and nasal bones
smaller frontal sinuses (may be absent in Persians)
more complete bony orbits
wider skulls ( due to wider zygomatic arches)

10. Rads or CT? CT Elimination of superimposition
Ability to display images in multiple planes
Shorter imaging time
Higher contrast resolution
Higher cost
Lower availability
CT and rads both underestimate presence of mild middle ear disease
CT more consistent for moderate/severe middle ear disease

11. nasopharyngeal polyps in cats
Benign growths
Nasopharynx, middle ear, external ear canal
Diagnostic Imaging:
Rads of skull with emphasis on tympanic cavities
Lateral oblique and open mouth views to see changes in tympanic bullae (normally contain air)
Rad changes suggesting polyps:
Soft tissue densities in bullae
Evidence of chronic otitis media (bony thickening)

12. CT – otitis media

13. Nasopharyngeal polyps
Rads: only partially sensitive diagnostic tool for otitis media
25% of animals with middle ear disease have no radiographic abnormalities
CT or MRI:
Define extent of mass in middle ear
Determines invasion into inner ear, pharynx, outer ear more clearly than rads

14. Nasopharyngeal polyps

15. Nasopharyngeal polyps

16. Feline skull

17. Nasopharyngeal polyps

18. Other Skull Problems Tempromandibular joint disease Otitis Tumors
Canine craniomandibular osteopathy
TMJ dysplasia
Luxation/subluxation
Fracture
Ankylosis
Otitis
Externa
Media
Interna
Tumors

19. TMJ
TMJ “hinge joint” – condyloid process of mandible articulates with mandibular fossa of temporal bone

20. DV of left TMJ M= mandible PC=coronoid process of ramus of mandible
Z= zygomatic arch
C= condyloid process of mandible
a = angular process of mandible
F= mandibular fossa
P= articular process of temporal bone
Between arrowheads = thin, radiolucent TMJ space

21. Canine CranioMandibular Osteopathy
Unknown etiology
Common in West Highland, Scottish, and Cairn terriers
Extensive, bilateral, irregular, periosteal reaction of mandible
Extend to TMJ, tympanic bullae, calvarium
Rads to investigate TMJ
Dogs have difficulties opening mouth during mastication

22. Craniomadibular Osteopathy

23. TMJ Luxation
Consequence of trauma, dysplasia, degeneration, idiopathic condition
Condylar process of mandible luxated rostrodorsally
Dental malocclusion present
Unilateral luxation w/ mandibular fx (dogs)
Unilateral luxation with or without mandibular fx (cats)

24. TMJ luxation
Mandibular fossa of temporal bone is not articulated with condyloid process of mandible. The condyloid process has rotated forward and upward.

25. TMJ ankylosis Relatively uncommon or undiagnosed
Abnormal immobility and consolidation of a joint
Consequence of untreated intra-articular (true ankylosis) or extra-articular (false ankylosis) trauma
Hemarthrosis syspected as initiating factor
Cat falling from great height
From extensive new bone formation
otitis media or canine craniomandibular osteopathy

26. Transverse CT image: Bilateral true ankylosis
TMJ ankylosis
Transverse CT image: Bilateral true ankylosis

27. TMJ tumors Most common: Characteristic appearance on rads, CT, MRI
Osteosarcoma
Multilobular osteochondrosarcoma
Characteristic appearance on rads, CT, MRI
Rounded, well defined, osseous mass
Course, granular architecture arising from mandible, zygomatic arch or other flat bones of skull

28. TMJ tumor
Transverse (A) and Dorsal (B) plane images: lobulated bony mass arising from left maxilla and zygomatic bone with compression (not invasion) of adjacent bone. Characteristic of multilobular osteochondrosarcoma.