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02/11/2020
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“ Connecting the dots between Radiology, Embryology and Genetics”
felice.d’arco@gosh.nhs.uk@FeliceDArcoLectures are on Youtube!https://www.slideshare.net/bluetango84
Joshi et al. 2012
“a reflection on the complexity of life”Karina Ter
Current Embryology of the Temporal Bone, Part I: the Inner Ear P.M. Som, H.D. Curtin, K. Liu, and M.F. Mafee. Neurographics 2016
What do we know about genotype‐phenotype correlation?
SOX family
DIX family
FOX family
FGF family
Acidosis and deafness in patients with recessive mutation in FOXI1
J Am Soc Nephrol. 2018
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Classification of Inner Ear Malformations
Joshi et al. 2012
No pathophysological correlation (only timing of arrest)
Only one type of cochlear hypoplasia
Only two type of incomplete partition
Sennaroglu L 2016
Complete Labyrinthine Aplasia (Michel Deformity)
Joshi et al. 2012
Ozgen et al. 2009
Rudimentary otocyst
Between 3rd and 4th week the inner ear is in form of an otocyst
Millimetric round‐shaped cyst in the oticcapsule
Absent or small IAC ABI is the only therapy
Sennaroglu 2016
Common Cavity
Unique cavity before differentiation into cochlea and vestibule (4th week)
IAC present (narrow or normal) CN present (often hypoplastic) Possible Cochlear implantation
Cochlear aplasia
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Cochlear hypoplasias
“Clear and definite formation of a cochlea whose external
dimensions are less than those of a normal cochlea.”
Incomplete Partition Anomalies
“Cochlea with internal architecture abnormalities
(i.e. modiolus, ISS).”
• Are cochleas with abnormal internal structure of normal or small size?
• Do hypoplasticcochleas always have an abnormal internal structure?
1.5 cochlear turns: 8 wks2.5 cochlear turns: 10 wks!
BLOOD FLOW FROM IAM !!
Gulya and Schuknecht 2007; Erixon 2009 ; Sennaroglu 2016
•CH I and CH II are smaller versions of a cochlea with incomplete partition
•CH‐III and CH‐IV are smaller versions of a normal partitioned cochlea.
“Because of the resolution of CT the modiolardefects may be not identified”
Relatively high percentage of CH among inner ear malformations: 18/33 (Sennaroglu 2016)
Possible usefulness of standardized measurements
CH type 2CH type 1
CH type 3
CH type 4
Talenti et al. BJR 2018
Is there CH? maximal height in a coronal plane measured perpendicular to the oval window
Is there dysplastic SCC? maximal diameter of bony island among axial slices displaying an intact semicircle
Is there EVA 1) midpoint: width of VA at halfway between the posterior wall of the vestibule and aperture of VA. 2) Opercular width: width of aperture of VA
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ax
21 month‐old, female: Profound bilateral SNHL
parasag
Incomplete Partition Type 1
‐ Radiographics 2012; 32 (3), 683‐698‐ Cochlear Implants International 2016; 17 (1), 1‐20
IP 1 Syntelencephaly
C. Aplasia + dysplastic SCC
Mutations in
ZIC2, postulated
in the
pathogenesis of
HPE and
syntelencephaly
Zic genes are
required for
morphogenesis
of the inner ear
(Chervenak et
al 2014)
5 year‐old: Profound bilateral SNHL
Incomplete Partition Type 2 + dilated vestibule + EVA (Mondini
triad)
Normal
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Normal
Incomplete Partition type 2
Association with EVA and Dilated vestibule
Dilatation of the Scala Vestibuli Possible aetiology: High CSF pressure
transmitted to the cochlea via third window?
Endolymphatic duct and sac
are not surrounded by
a perilymphaticspace. (Lo et al
AJNR 1997)
Different embryiological origin of
distal IS
Endolymphatic sac!
“apparent band‐like area of low T2 extending from the modiolus towards the lateral wall of the cochlea in the same patient (arrow).”
“the spiral ganglion neuron dendritic processes continued toward the upper middle turn through the osseous spiral lamina.”
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“A measured angle of >114°suggests the diagnosis of incomplete
partition type II malformation”
“cut‐off 1.2 mm between normal/abnormal”
1 year‐old male: progressive mixed hearing loss Incomplete Partition type 3
‐ POU3F4 gene mutation
‐ Large IAC‐ IS present‐ Modiolus /LS absent
Dysmorphic hypothalamus
“POU3F4 mainly participates in the regulation of neural stem cells, hypothalamus
differentiation and inner ear development”
The developmental link between inner ear, brain and body: clues for many diagnosis !
Pallister‐Hall syndrome: HH and cochlear hypoplasia association
Avula et al. Ped Rad 2012
Giri et al. IJCP 2015
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The developmental link between inner ear, brain and body: clues for many diagnosis !
D’Arco et al. EJR 2020
Typical petrous bone findings + associated body findings in syndromic causes of hearing loss
BOR
CHARGE
PENDRED
SOX 10
Diagnostic Pearl: Waardenburg Syndrome
• Pigmentation changes + deafness
• Several genes: SOX 10 Hirschsprung disease + Kalmann
• Typical cochlea hypoplasia/dysplastic SCCs
Child with Hirschprung + hearing loss
Hsu et al. AJNR 2018
MRI of the inner ears in a 10 year‐old female with chronic kidney disease, dysmorphic features, bilateral hearing loss and mosaic trisomy of chromosome 22. Bilateral CH4 is demonstrated with
normal‐sized basal turn and very hypoplastic upper turns. Normal lamina spiralis is noted as an hypointense line within the basal turn
(arrows).
Right Left
Cochlear Hypoplasia Type 4
Article In Press AJNR 2020
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Suggested readings….
Conclusions
New classification of inner ear malformations based on histology
Spectrum of cochlear hypoplasias and 3 types incomplete partition cochleas
Link between ear, brain and body development helps in the DDx
Syndromic causes of hearing loss may have characteristic petrous bone appearances.
felice.d’arco@gosh.nhs.uk
https://www.slideshare.net/bluetango84
Youtube: Felice D’Arco
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