Presentation on theme: "Chinchilla skull – notice the large bullae!"— Presentation transcript:
1Chinchilla skull – notice the large bullae! The SkullMelanie EaganChinchilla skull – notice the large bullae!
2Indications for skull rads Neurological problemsNasal problemsMandibular problemsMaxillary problems1̊ tumors of skullMass behind eyeTeeth diseasesMiddle ear problems
3Views Careful positioning is necessary Sedation or GA usually necessaryPositioning aids to elevate cassette
4Intraoral dorsoventral view Good for rostral aspect of nasal cavities
5Ventrorostral-dorsocaudal oblique Good for more caudal aspect of nasal cavitiesMore difficult to assess rostral aspect of nose (shortened by angulation of x-ray beam)
6Rostrocaudal viewPatient positioning for rostrocaudal rads of frontal sinuses taken with vertical beam
7Rostrocaudal 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
8Lateral oblique used to view: Tempromandibular jointTeeth in mandible/maxillaFractures in mandible/maxilla
9differences in the cat skull Dog skull – leftCat skull – rightArrow pointing to cribiform plateCats have:greater doming on frontal and nasal bonessmaller frontal sinuses (may be absent in Persians)more complete bony orbitswider skulls ( due to wider zygomatic arches)
10Rads or CT? CT Elimination of superimposition Ability to display images in multiple planesShorter imaging timeHigher contrast resolutionHigher costLower availabilityCT and rads both underestimate presence of mild middle ear diseaseCT more consistent for moderate/severe middle ear disease
11nasopharyngeal polyps in cats Benign growthsNasopharynx, middle ear, external ear canalDiagnostic Imaging:Rads of skull with emphasis on tympanic cavitiesLateral oblique and open mouth views to see changes in tympanic bullae (normally contain air)Rad changes suggesting polyps:Soft tissue densities in bullaeEvidence of chronic otitis media (bony thickening)
13Nasopharyngeal polyps Rads: only partially sensitive diagnostic tool for otitis media25% of animals with middle ear disease have no radiographic abnormalitiesCT or MRI:Define extent of mass in middle earDetermines invasion into inner ear, pharynx, outer ear more clearly than rads
19TMJTMJ “hinge joint” – condyloid process of mandible articulates with mandibular fossa of temporal bone
20DV of left TMJ M= mandible PC=coronoid process of ramus of mandible Z= zygomatic archC= condyloid process of mandiblea = angular process of mandibleF= mandibular fossaP= articular process of temporal boneBetween arrowheads = thin, radiolucent TMJ space
21Canine CranioMandibular Osteopathy Unknown etiologyCommon in West Highland, Scottish, and Cairn terriersExtensive, bilateral, irregular, periosteal reaction of mandibleExtend to TMJ, tympanic bullae, calvariumRads to investigate TMJDogs have difficulties opening mouth during mastication
23TMJ LuxationConsequence of trauma, dysplasia, degeneration, idiopathic conditionCondylar process of mandible luxated rostrodorsallyDental malocclusion presentUnilateral luxation w/ mandibular fx (dogs)Unilateral luxation with or without mandibular fx (cats)
24TMJ luxationMandibular fossa of temporal bone is not articulated with condyloid process of mandible. The condyloid process has rotated forward and upward.
25TMJ ankylosis Relatively uncommon or undiagnosed Abnormal immobility and consolidation of a jointConsequence of untreated intra-articular (true ankylosis) or extra-articular (false ankylosis) traumaHemarthrosis syspected as initiating factorCat falling from great heightFrom extensive new bone formationotitis media or canine craniomandibular osteopathy
27TMJ tumors Most common: Characteristic appearance on rads, CT, MRI OsteosarcomaMultilobular osteochondrosarcomaCharacteristic appearance on rads, CT, MRIRounded, well defined, osseous massCourse, granular architecture arising from mandible, zygomatic arch or other flat bones of skull
28TMJ tumorTransverse (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.