CONGENITAL HEARING LOSS Hear the Signs Atat C

CONGENITAL HEARING LOSS Hear the Signs Atat C 1 ║ Yazbek S 1 ║ Haddad A 1 ║ Abi Khalil S 1 ║ Slaba S 1 ║ Robson C 2, 3 1 Hotel Dieu de France Hospital, Beirut, Lebanon 2 Boston Children's Hospital, Boston, MA e. Ed. E-126 3 Harvard Medical School, Boston, MA

DISCLOSURES Atat C, Yazbek S, Haddad A, Abi Khalil S, Slaba S: No disclosures Robson CD: Royalties Elsevier Inc.

OBJECTIVES • Develop a structured approach to reading a temporal bone CT for Congenital Hearing Loss (CHL) • Describe the cases where an MRI of the inner ear structures is recommended • Know the etiologies of CHL where a cochlear implant should be avoided

HOW TO BROWSE THE CASES • We recommend a structured approach starting with the EAC and ending with the brain parenchyma • You can also go straight to the area of interest by clicking directly on it • In most cases, a hint can be solicited by clicking on Hint

Washington Otology © Click on the area you want to explore.

Washington Otology © External Auditory Canal

Washington Otology © Middle Ear

Washington Otology © Inner Ear

Washington Otology © Cerebellopontine Angle – Brain Parenchyma

EXTERNAL AUDITORY CANAL

Right external auditory canal atresia Hypoplastic MEC Malformed ossicles Hint

Congenital External and Middle Ear Malformation (CEMEM) External Auditory Canal Atresia and Stenosis Best imaging tool: T-bone CT with 2 D reconstruction • Malformed pinna: Severity of microtia approximates severity of CEMEM. • Variable severity, from EAC atresia with absent tympanic plate and severe middle ear and ossicular anomalies to mild EAC stenosis with mild middle ear and ossicular anomalies • EAC anomalies are associated with malformed middle ear cavity & contents (EAC & MEC structures are derived from branchial apparatus while inner ear structures are derived from otic vesicle). • Anomalies of inner ear unusual in CEMEM unless syndromic. Rt EAC atresia; tympanic plate absent CT provides pre-operative roadmap: Establish course of CN 7 and status of ossicular chain, oval window and inner ear before surgery. EAC stenosis; tympanic plates present but hypoplastic

Example of Syndromic EAC Atresia: Fanconi Anemia: EAC and Inner Ear Malformation Left microtia (white arrow) Distal turns of the cochlea are normal Basal turn tapering of cochlea (arrows) Bilateral EAC atresia (arrows) V/S Normal A metacarpal bone is missing in the thumbs (white arrows)

Key Points in your report CEMEM 1. EAC stenosis (small tympanic plate) vs atresia 2. Atresia plate thickness; bony vs membranous 3. Describe mastoid pneumatization 4. Middle ear space size; malformation 5. Erosive opacity c/w cholesteatoma 6. Ossicles: malformation, rotation, fusion 7. Oval window: stenosis or atresia 8. Facial nerve course, dehiscence 9. Inner ear anomalies 10. Mandibular condyle size/position 11. Zygomatic arch anomaly 12. Low placement of middle cranial fossa dura

END OF “EXTERNAL AUDITORY CANAL” SECTION

MIDDLE EAR Case 1/3

Small rounded soft tissue mass medial to the ossicles Hint

CONGENITAL CHOLESTEATOMA Best imaging tool: T-bone CT MR if large or recurrent or diagnosis uncertain • Small, well-circumscribed soft tissue middle ear mass, medial to ossicles with intact tympanic membrane, may erode ossicles and other bony structures. • MR: Peripheral enhancement, restricted diffusion. Treatment: complete surgical resection.

MIDDLE EAR Case 2/3

Axial Coronal Hint Ossicular fixation: head of the malleus to the roof of the middle ear manubrium of the malleus to the lateral wall of the middle ear

CONGENITAL OSSICULAR FIXATION Best imaging tool: High-resolution T-bone CT • Congenital ankylosis: rigid bar or fibrous band connecting ossicle to wall of MEC. • Identify multiple fixations on CT. Treatment: mechanical division or various types of laser vaporization of bony ankylosis.

MIDDLE EAR Case 3/3

Coronal Ossification overlies oval window Facial nerve overhangs the oval window Axial Hint

OVAL WINDOW ATRESIA Best imaging tool: T-bone CT with coronal reconstruction CT findings: • Approximation of bone beneath lateral SCC with bone over cochlear promontary • Inferomedially or inferolaterally positioned tympanic segment of CN 7 • Bilateral in 40% Normal oval window Treatment: • Vestibulotomy with stapes prosthesis or total ossicular replacement prothesis (TORP) • CN 7 ectopia is a relative surgical contraindication Aberrant facial nerve canal Oval window atresia

END OF “MIDDLE EAR” SECTION

INNER EAR Case 1/10

Axial Coronal Complete absence of the cochlea Cystic space representing the right vestibule and lateral SCC Rudimentary superior SCC Hint

COCHLEAR APLASIA Best imaging tool: T-bone CT or MR • No cochlea seen on CT or T 2 MR but rest of membranous labyrinth is present (with variable abnormalities) • Usually bilateral Treatment: • Brainstem implantation if bilateral • Cochlear implant contraindicated Springer Science and Business Media ©

Case 1/10 continued: Contralateral side Axial Coronal V/S Normal Complete labyrinthine aplasia

LABYRINTHINE APLASIA Best imaging tool: T-bone CT or MR • Absent/hypoplastic otic capsule bone • Absent cochlea, vestibule and SCC • Often asymmetric: contralateral common cavity, inner ear hypoplasia or cochlear IP-I anomaly Treatment: • Brainstem implantation if bilateral • Cochlear implant contraindicated Springer Science and Business Media ©

INNER EAR Case 2/10

Cystic Cochlea with an absent interscalar septum and modiolus Dilated Vestibule 8 Hint

COCHLEAR INCOMPLETE PARTITION TYPE 1 (IP-I) Best imaging tool: MR 3 D T 2 weighted sequence (Fiesta/CISS/Space) to identify CN 8 components. • Absent interscalar septum and modiolus, dilated SCC → Cystic Cochleovestibular Malformation (figure of 8) • CN 8 : Hypoplastic or absent Treatment: • None if contralateral ear is normal. • Cochlear implantation if cochlear nerve present • May be at risk of CSF gusher/perilymph leak Springer Science and Business Media ©

INNER EAR Case 3/10

Absent Interscalar septum between plump middle & apical turns ( ) Smooth external contour between middle & apical turns posterolaterally ("baseball cap" cochlea) Hint

What is the frequently associated finding? Bilateral IP-II with modiolar deficiency + Large right vestibular aqueduct Axial Hint Sagittal Oblique

COCHLEAR INCOMPLETE PARTITION TYPE 2 (IP-II) Best imaging tool: T-bone CT and MR (3 D T 2) • Cochlea: • Absent interscalar septum between middle and apical turns ( « Baseball cap » cochlea) • Deficient or absent modiolus • Usually associated with large vestibular aqueduct/large endolymphatic sac/duct: • ≥ 1 mm at midpoint • ≥ 2 mm at operculum Treatment: • Avoid contact sports and prevent head trauma • Cochlear implantation if profound bilateral SNHL Springer Science and Business Media ©

INNER EAR Companion case: Case 4/10

Hypothyroidism and Goiter Bilateral IP-II ( ) and Large Vestibular Aqueducts ( ) Additional history

PENDRED SYNDROME Autosomal recessive • Thyroid organification defect • SNHL (fluctuating/progressive): LVA +/- IP-II • SLC 26 A 4 mutation Treatment: Cochlear implantation for profound bilateral SNHL Springer Science and Business Media ©

INNER EAR Case 5/10

Normal Right side Stenotic cochlear nerve canal and thickened modiolus Hint

COCHLEAR NERVE CANAL APLASIA Best imaging tool: Axial and sagittal oblique 3 D T 2 weighted sequence Normal Hypoplasia Atresia • Cochlea nerve canal stenosis < 1. 7 mm. Diameter is measured at its narrowest point. Treatment: • Brainstem implantation if CN absent • Cochlear implantation (CI) relatively contraindicated • However, may have some function with CI if some nerve fibers are present Springer Science and Business Media ©

INNER EAR Case 6/10

Axial Sagittal Oblique through the left IAC Sagittal Oblique through the right IAC Compared to the contralateral side, the left side shows an absent cochlear nerve ( ) The right side is normal and shows an anterosuperior facial nerve, an anteroinferior cochlear nerve and posterior superior and inferior vestibular nerves Hint

COCHLEAR NERVE APLASIA Best imaging tool: Axial and sagittal oblique 3 D T 2 weighted sequence • Cochlear Nerve Deficiency: Cochlear nerve smaller than normal CN 7 (hypoplasia) or absent (aplasia). Treatment: • Brainstem implantation • Cochlear implantation contraindicated Springer Science and Business Media ©

INNER EAR Case 7/10

Bilateral flattened cochlea ( ) Short and thick posterior semicircular canal ( ) Pigmentary anomalies: • Blue eyes • White hair Hirschsprung Hint

WAARDENBURG SYNDROME type IV • • • SCC: Shortened, thick posterior SCC Vestibule and VA: Normal or enlarged Cochlear: Normal or flattened Cochlear nerve: Normal or absent Brain: +/- Abnormal myelination Waardenburg syndromes: Variable pigmentary anomalies, SNHL, variable dystopia canthorum, upper limb anomalies, Hirschsprung disease (type IV), peripheral neuropathy, ataxia…

WAARDENBURG SYNDROME Best imaging tool: MR 3 D T 2 weighted sequence (Fiesta/CISS/Space) to identify CN 8 components. Treatment: Cochlear implantation if cochlear nerve present ? Springer Science and Business Media ©

INNER EAR Case 8/10

Dilated IAC ( ) Widened cochlear apertures ( ) Dysmorphic cochlea with a “corkscrew appearance” ( ) Hint

X-LINKED STAPES GUSHER Best imaging tool: T-bone CT and MR • • Cochlea: « Corkscrew » appearance Cochlear nerve canal: Widened IAC: Bulbous dilatation Facial nerve canal: Wide labyrinthine and proximal tympanic segments • Dilated lateral SCCs Treatment: Cochlear implantation with risk of CSF gusher and meningitis ? Springer Science and Business Media ©

INNER EAR Case 9/10

Coloboma ( ) Cochlear malformation ( ) Small vestibules, absent SCC ( ) Absent olfactory nerve on the right, small on the left Hypoplastic clivus, basilar invagination, small pons, inferior vermian hypoplasia, small pituitary Hint Choanal atresia Hypoplastic CN 7, 8 ( ) Right trigeminal artery ( )

CHARGE SYNDROME Coloboma Heart anomaly Atresia choanae Retardation: mental & somatic Genital Hypoplasia Ear abnormalities

CHARGE SYNDROME Imaging: • Choanal atresia, coloboma, cleft lip/palate • Hypoplastic vestibule & hypoplastic/absent SCC • Funnel shaped enlarged vestibular aqueduct • Ossicular anomalies • Thickened modioli, stenotic/absent cochlear nerve canals • Flattened or absent apical and middle cochlear turns • Stenotic/atretic oval windows & overlying anomalous tympanic segments of CN 7 • Large emissary veins, stenotic jugular foramina, hypoplasia basiocciput, basilar invagination, & spinal anomalies • Hypoplastic pons, cerebellar malformation • CN hypoplasia/aplasia (mainly CN 1, 7 & 8)

CHARGE SYNDROME Best imaging tool: MR 3 D T 2 weighted sequence (Fiesta/CISS/Space) to identify CN 8 components. Treatment: Cochlear implantation if cochlear nerve present ? Springer Science and Business Media ©

INNER EAR Case 10/10

Tapered basal turn of the cochlea ( ) + unwound/offset, hypoplastic middle & apical turns Fusion of malformed ossicles to the attic bilaterally Malformed posterior semicircular canals Funnel shaped enlargement of Vestibular Bilateral microtia with bilateral atresia of Aqueducts bilaterally the external auditory canals Type 1 branchial cleft cyst Renal cysts

BRANCHIO-OTO-RENAL SYNDROME Autosomal dominant Deafness + Branchial cleft cyst/fistula + Ear anomalies + Renal anomalies (cysts, dysplasia, agenesis) EYA 1 gene mutation Best imaging tool: T-bone CT • Dilated eustachian tubes • EAC: stenosis/atresia • Middle ear: dysmorphic/fused ossicles • Cochlea: Tapered basal turn, hypoplastic, offset middle/apical turn → unwound appearance • SCC anomaly • Dilated, bulbous VA • Flared IAC • Anomalous CN 7 canal Treatment: Cochlear implantation for profound bilateral SNHL Springer Science and Business Media ©

END OF “INNER EAR” SECTION

CEREBELLOPONTINE ANGLE – BRAIN PARENCHYMA Case 1/2

T 2 T 1+C FLAIR Nonenhancing mass within the left CP angle presenting restricted diffusion DWI ADC

CEREBELLOPONTINE ANGLE EPIDERMOID CYST Best imaging tool: MR MR findings: • CPA cisternal insinuating mass • Iso or slightly hyperintense on T 1 and T 2 • Does not attenuate on FLAIR • Restricted diffusion • Although congenital, it usually presents in adult life. Treatment: Complete surgical resection DWI MR to diagnose recurrences

CEREBELLOPONTINE ANGLE – BRAIN PARENCHYMA Case 2/2

Normal Temporal bone CT Periventricular calcifications Thick cortex. Further evaluation with an MRI of the brain was recommended.

MRI was performed Sag T 1 Ax T 2 Cor T 2 Fatsat MRI demonstrates diffuse bilateral polymicrogyria in the frontal lobes, along the sylvian fissures and in the parietal and temporal lobes. The polymicrogyria and the periventricular calcifications are in favor of a diagnosis of congenital CMV infection as the cause of congenital SNHL

CMV INFECTION CT: • Intracranial calcifications: in germinal matrix, periventricular regions and basal ganglia • White matter low density regions • Ventriculomegaly/cerebral atrophy/destructive encephalopathy • Neuronal migration disorders MR: • Microcephaly • Migrational abnormalities : polymicrogyria • White matter lesions • Ventriculomegaly and subarachnoid space enlargement • Periventricular and temporal pole cysts • Delayed myelination

END OF “CEREBELLOPONTINE ANGLE – BRAIN PARENCHYMA” SECTION

SUMMARY • A patterned approach to reading a temporal bone CT for CHL simplifies the radiological diagnosis of complex pathology. • MR imaging is preferred in cases where lesions in the inner ear, cranial nerves or brain are suspected (sensorineural hearing loss). • Cochlear aplasia, cochlear nerve aplasia and cochlear nerve aperture aplasia should be identified, as they constitute absolute or relative contraindications to cochlear implants. • A relative contraindication to cochlear implantation is the risk of CSF gusher from a dilated cochlear nerve aperture with absence of the modiolus. • Keep in mind that only 20 to 30% of CHL will present anomalies on imaging, since hearing loss is frequently due to isolated abnormalities on a cellular or microscopic level.

REFERENCES • Robson, Koch, Harnsberger. Specialty Imaging, Temporal Bone. Amirsys • B. Y. Huang, C. Zdanski, and M. Castillo. Pediatric Sensorineural Hearing Loss, Part 1: Practical Aspects for Neuroradiologists. AJNR Am J Neuroradiol; 2012 33: 211217 • B. Y. Huang, C. Zdanski, and M. Castillo. Pediatric Sensorineural Hearing Loss, Part 2: Syndromic and Acquired Causes. AJNR Am J Neuroradiol 2012; 33: 399 -406 • Robson CD. Congenital hearing impairment. Pediatr Radiol. 2006; Apr; 36(4): 309 -24. • Billings KR, Kenna MA. Causes of pediatric sensorineural hearing loss: yesterday and today. Arch Otolaryngol Head Neck Surg 1999; 125: 517