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The Skull Chinchilla skull notice the large bullae! Melanie Eagan Slide 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 Slide 3 Views Careful positioning is necessary Sedation or GA usually necessary Positioning aids to elevate cassette Slide 4 Intraoral dorsoventral view Good for rostral aspect of nasal cavities Slide 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) Slide 6 Rostrocaudal view Patient positioning for rostrocaudal rads of frontal sinuses taken with vertical beam Slide 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 Slide 8 Lateral oblique used to view: -Tempromandibular joint -Teeth in mandible/maxilla -Fractures in mandible/maxilla Slide 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 Slide 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 Slide 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) Slide 12 CT otitis media Slide 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 Slide 14 Nasopharyngeal polyps Slide 15 Slide 16 Feline skull Slide 17 Nasopharyngeal polyps Slide 18 Other Skull Problems Tempromandibular joint disease Canine craniomandibular osteopathy TMJ dysplasia Luxation/subluxation Fracture Ankylosis Otitis Externa Media Interna Tumors Slide 19 TMJ TMJ hinge joint condyloid process of mandible articulates with mandibular fossa of temporal bone Slide 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 Slide 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 Slide 22 Craniomadibular Osteopathy Slide 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) Slide 24 TMJ luxation Mandibular fossa of temporal bone is not articulated with condyloid process of mandible. The condyloid process has rotated forward and upward. Slide 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 Slide 26 TMJ ankylosis Transverse CT image: Bilateral true ankylosis Slide 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 Slide 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. Slide 29