3. 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
4. CT SCAN
§ 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
8. CT findings: the surgeon
expectations
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
9. Reading method
§ 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
10. Reading method
§ Inner ear:
ú Malformation of semi-circular canal or
vestibular abnormality
ú Fenestration of the LSCC
ú Exclude a gusher syndrom: modiolus
>2,7mm
11. Key points
§ 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
12. 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.
13. 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
14. 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
15. Pathologies
§ Superior canal dehiscence
(Minor’s syndrom) :
Importance of the 2D
reconstruction
perpendicular to the axis
of the canal
16. Temporal bone injury
§ Third leading cause of
conductive hearing loss
§ CT scan: incudostapedial or
incudomalleus discolation
(55 - 60%)
§ Fracture of the stapes Diastasis > 1 mm
18. 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
19. CT scan
ú 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
20. Otospongiosis: CT scan
§ 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.
22. Otospongiosis: CT scan
§ 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
24. Otospongiosis: CT scan
§ 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.
33. Pneumolabyrinth
§ Air in inner ear cavities
§ Pathognomonic of a
perilymphatic fistula
§ But it can be observed after
stapedectomy without
pejorative significance
38. 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