f benoudiba jl sarrazin transmissional hearing loss with normal tympanic membran jfim 2014
TRANSCRIPT
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CONDUCTIVEHEARINGLOSSWITHNORMALTYMPANICMEMBRAN
F.BENOUDIBA,JLSARRAZINServicedeNeuroradiologieCHUKremlinBicêtre
JFIMBarcelonanov1st2014
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Conductivehearinglosswithnormaltympanicmembran§ 4 different kinds of pathologies
ú Otosclerosis ú Post traumatic ú Chronic otitis ú Malformations: minor aplasia, gusher syndrom
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Diagnosis
§ Anamnesis and clinical findings § Personal and family medical history § Partial or bilateral hearing loss § Acquired, increasing hearing loss § Normal tympanic membran § Conductive or mixed hearing loss § Absence of stapedial reflex § IMAGING RECOMMANDATION: CT
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CTSCAN
§ No injection, Bone CT § Thin sections // skull
base, above the crystaline § // LSCC § Sections: 0,4mm,
reconstructions 0,5mm § Coronal reconstructions
perpendicular to LSCC § Oblique reconstructions
perpendicular to the stapes footplate: « V » ossicular
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CBCT:XRaycomptutedtomography
§ Sectionalimaging,3Dreconstruction§ Boneanalysis§ LessirradiationthanCTscan(4to12less)§ Lessartifacts
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CBCT:XRaycomptutedtomography§ 250to360aquisitions§ Isotopricvoxel§ Spatialresolution:100μ
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ANALYSECEPHALOMETRIQUETRIDIMENSIONNELLE(J.TREIL)
LogicielDolphin
3D
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CTfindings:thesurgeonexpectations
Pre operative Ø Diagnosis
Ø Diagnosis ⊕ > 90% Ø Différential diagnosis or other pathology associated Ø Surgical anatomical informations
Ø Oval window niche size, position of VII, occlusion of the oval window, vascular variants
Ø Prognosis evaluation: round window occlusion, cochlear otosclerosis, endosteum extension
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Readingmethod
§ External auditory meatus: ú walls, content
§ Middle ear ú walls, content: size, shape, ossicular morphology,
aeration of the tympanic cavity ú Fenestral: thickness, size of recess, thickness of
the stapes footplate < 0,7 mm (axial ) ú Position of the facial nerve, especially up to the
oval window
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Readingmethod
§ Inner ear: ú Malformation of semi-circular canal or
vestibular abnormality ú Fenestration of the LSCC ú Exclude a gusher syndrom: modiolus
>2,7mm
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Keypoints
§ Conductive hearing loss are not only secondary of middle ear or windows pathologies
§ Inner ear lesions can also be responsible as: ú Labyrinthine malformation ú Fixed stapes footplate
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Pathologies§ Malformation
ú Fixation of the ossicular chain Fixation of the head of the
malleus (Goodhill syndrom): calcified bridge between the head of the malleus and the lateral or the the anterior wall of the attic wall.
Rare 1% Inflammatory or traumatic
secondary ossification.
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Pathologies§ Malformation
Fixation of the long process of the incus Absence of the long process of the incus Absence or distorsion of the stapes Agenesia of the round window
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Pathologies
§ Malformatiion ú Gusher syndrom: inherited
hearing loss X-linked Perilymphatic communication with sub arachnoid space.
ú Geyser fluid through the
stapes floot plate during surgical platinotomy with cophosis
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Pathologies
§ Superior canal dehiscence (Minor’s syndrom) : Importance of the 2D reconstruction perpendicular to the axis of the canal
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Temporalboneinjury
§ Third leading cause of conductive hearing loss
§ CT scan: incudostapedial or incudomalleus discolation (55 - 60%)
§ Fracture of the stapes Diastasis > 1 mm
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Temporalboneinjury
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Pathologies
§ Otospongiosis ú Common ú Perifenestral bony labyrinth pathology where
spongy bone foci appear ú Bilateral 2 /3, often asymmetrical ú 0,5 à 1% of caucasian population ú Women more often (sex ratio 2/1) from 15 to 45
years old. ú Very rare less than 10 years old
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CTscanú Lytic foci on anterior
margin of oval window (Fissula antefenestram)
ú Extension to the stapes footplate with fixation of the stapes
ú Spreads to involve all margins of oval and round window
CT
CBCT
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Otospongiosis:CTscan § Isolated lesion on the stapes
footplate
ú Unusual (0.02 %). ú Normal size of the stapes
footplate < 0,3 mm on histological section
ú Size on CT varies from 0,4 to 0,55.
ú Physiological anterior thickening close to the anterior branch of the stapes
ú Only an important thickening is available(> 0,7 mm ) to be significant.
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Otospongiosis:CTscan
§ Extensiontoendosteum
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Otospongiosis:CTscan§ Hypertrophic Foci
ú May result a fixation of the ossicular chain to the medial wall of the tympanic cavity (stapes, malleus and incus rarely)
ú It can narrow the oval window: surgical difficulty
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Otospongiosis:CTscan§ Foci of the round
window: poorpostoperativeresults
§ Superior canal dehiscence
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Otospongiosis:CTscan§ Labyrinthine foci are rarely
isolated, usually associated with anterior location.
§ Double ring appearance. § Posteriorlabyrinth lesions
are unusual, most frequently seen around the lateral canal
§ Foci located to the internal auditory meatus are very rare.
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DifferentialDiagnosis
§ Osteogenesis imperfecta
§ Phosphate metabolism disturbance
§ Paget disease
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Preoperativestaging§ Superior canal dehiscence § Ovalwindow’ssize§ Prolapsedfacialnerve§ Vascularvariants§ Enlargedmodiolus
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Failureandsurgicalcomplicationsimaging
§ Failure : Hearing loss persistence or recurrence: prothesis dysfunction
§ Complication : sensorineural hearing loss
(vertigo): inner ear suffering
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Failureandsurgicalcomplicationsimaging
§ Conductive hearing loss § CT
ú Displacement or migration of prosthesis
ú Erosion of incus ú Fibrosis ú Attic ankylosis ú Otosclerosis proliferation ú Prosthesis too short ú Incus dislocation
§ Sensorineural hearing loss
§ CT +/- MRI § Perilymphatic fistula § Intravestibular prosthesis § Inner ear infection § Granuloma around the oval
window
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Prosthesisdisplacement
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CBCT
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Erosionofincus CBCT
CT
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Intravestibularprosthesis
§ Intravestibular penetration>1 mm (WITH clinical inner ear symptoms)
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Pneumolabyrinth§ Air in inner ear cavities § Pathognomonic of a
perilymphatic fistula § But it can be observed after
stapedectomy without pejorative significance
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NoexplanationonCT
§ No pneumolabyrinth
§ Airy middle ear cavity § Prosthesis well
positioned
§ Non specific opacity in the middle ear cavity
OR
MRI
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Perilymphaticfistula
§ Pneumolabyrinth: suggestive of PLF if seen afar surgery
§ Surgical revision if: Vertigo, nystagmus Conductive hearing loss
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Infection
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Intra-labyrinthichemorrhage
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Conclusion
§ Imaging has a key role
§ CT scan or cone beam are the best imaging
§ Child conductive hearing loss : CT systematic
§ Adult conductive hearing loss : useful for the diagnosis
§ Systematic in pre-operative or if failure or complication before surgical revision