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

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Presentation on theme: "The Skull Chinchilla skull – notice the large bullae! Melanie Eagan."— Presentation transcript:

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

2 Indications for skull rads Neurological problems Nasal problems Mandibular problems Maxillary problems 1 ̊ 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 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) Arrow pointing to cribiform plate

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 Polyps: –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


16 Feline skull

17 Nasopharyngeal polyps

18 Other Skull Problems Tempromandibular joint disease –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 TMJ ankylosis Transverse CT image: Bilateral true ankylosis

27 TMJ tumors Most common: –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.


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