1. Radiology, embryology and genetic…
what’s new
felice.d’arco@gosh.nhs.uk

2. Joshi et al.
2012

3. 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
Membranous labyrinth becomes
surrounded by mesenchyme
From mesenchyme to Cartilage matrix:
template for bony labyrinth (16-23th wks)
“ES and ED continue to change
throughout infancy and childhood.
Complete after puberty” Lo et al 1997
Perilymphatic space: 3rd to 5th month (important in
IP2!)
IS/modiolus : after perilymphatic
space
2.5 cochlear turns:
10 wks!

4. “a reflection on the complexity of life”
Karina Ter

5. 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

6. Cochlear aplasia

7. 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

8. 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 hypoplastic
cochleas always have
an abnormal internal
structure?

9. 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.

10. “Because of the resolution of CT the modiolar
defects 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

11. 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

12. Clinical implication
• Different prognoses depending on the type of
malformation (cochlear hypoplasia: lower level
of speech performance)
• Appropriate electrode choice may influence the
result of CI in cochlear hypoplasia
• Electrode thin (<0.8 mm) and short (< 20 mm)
Buchman et al. Cochlear Implantation in Children with Congenital Inner Ear Malformations.
Laryngoscope 2004

13. ax
21 month-old, female: Profound bilateral SNHL
parasag
Incomplete Partition
Type 1
Talenti et al. BJR 2018

14. - Radiographics 2012; 32 (3), 683-698
- Cochlear Implants International 2016; 17 (1), 1-20

15. IP 1 Syntelencephaly
C. Aplasia + dysplastic SCC
Mutations in
ZIC2,
postulated in
the
pathogenesis of
HPE and
syntelencephal
y
Zic genes are
required for
morphogenesis
of the inner ear
(Chervenak et
al 2014)

16. 5 year-old: Profound bilateral SNHL
Incomplete Partition Type 2 +
dilated vestibule + EVA (Mondini
triad)
Normal

18. Normal

20. 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?
 Partial abnormality of the internal
cochlear structure
 Syndromic association (Pendred)
ED and ES contain
only endolymph and
abundant stroma,
and are not
surrounded by a
perilymphatic
space. (Lo et al
AJNR 1997)
Genetic/embryogenetic association between upper
interscalar septum and ED/ES: PAX2, different
embryiological origin of distal IS

21. “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.”

22. “A measured angle of >114°
suggests the diagnosis of incomplete
partition type II malformation”
“cut-off 1.2 mm between
normal/abnormal”

23. 1 year-old male: progressive mixed hearing loss Incomplete Partition type 3
- POU3F4 gene
mutation
- Large IAC
- IS present
- Modiolus /LS absent

24. Incomplete Partition type 3: etiopathogenesis
normal
 Otic capsule is thinner in X-linked deafness if compared with normal
 In normal subject the endosteal layer of otic capsule follow the cochlear profile
 Enchodral and periosteal layers determine the increase of the thickness of the OC
 IP-III: otic capsule thinner and follow the profile of the cochlea (normal ISS)
 Enchodral and periosteal layers absent/hypodeveloped
 Enchodral and periosteal layers  vascular supply from the middle ear mucosa

25. “POU3F4 mainly participates in the regulation
of neural stem cells, hypothalamus
differentiation and inner ear development”Observation by Dr. A. Siddiqui

26. Diagnostic Pearl: Waardenburg Syndrome
• Pigmentation changes + deafness
• Several genes: SOX 10  Hirschsprung disease + Kalmann
• Typical cochlea hypoplasia/dysplastic SCCs
Child with Hirschprung + hearing loss

27. • Branchio-oto-renal syndrome: autosomal dominant
• hearing loss + auricular malformations + branchial arch closure defects +
renal anomalies.
• Findings in the ears: Cochlear hypoplasia + abnormal ossicles + other
1.5 y renal failure, preauricular tags, deafness

28. Pt.1: deafness, VACTERL Pt.2: deafness, cleft lip/palate, right microsomia, 1 kidney, hypospadia

30. felice.d’arco@gosh.nhs.uk