Congenital deafness has imaging diagnosis associated < 50%

If imaging diagnosis is found, large endolymphatic sac anomaly (incomplete partition type 2) is most common diagnosis discovered

All other inner ear congenital lesions that can be diagnosed by imaging are rare

Begin with T-bone CT

Add high-resolution T2 MR in axial and oblique sagittal plane when cochlear implant under consideration

Complex T-bone fractures may involve inner ear structures

T-bone CT: Fracture line crosses inner ear ± pneumolabyrinth

Clinical clues: Bilateral congenital SNHL that appears in child with cascading hearing loss pattern

Most common congenital imaging abnormality

CT: Enlarged bony vestibular aqueduct + mild cochlear dysplasia

MR: Enlarged endolymphatic sac + mild cochlear aplasia (modiolar deficiency, bulbous apical turn, scala vestibuli larger than scala tympani)

Clinical clues: Child develops profound SNHL after episode of meningitis or middle ear infection

Healing of suppurative labyrinthitis may result in osteoneogenesis within inner ear fluid spaces

CT: Ossific plaques impinges on inner ear fluid spaces

MR: High-resolution T2 shows encroachment on membranous labyrinthine fluid spaces

Asymptomatic normal variant that disappears in 1st 2 years of life

CT: Prominent canal passes beneath superior semicircular canal arch

MR: Conspicuous high signal canal on T2 imaging underneath superior semicircular canal

Clinical clues: Colobomata, heart defects, choanal atresia, retardation, genitourinary problems, ear abnormalities

CT: Bilateral semicircular canal absence, small vestibules, oval window atresia, cochlear nerve canal atresia

MR: Cochlear nerve absence

Clinical clue: Acute onset vertigo, hearing loss ± facial nerve paralysis

CT: Acute phase normal

MR: Often normal; if positive, diffuse enhancement of inner ear fluid spaces most common presentation

Clinical clue: May be idiopathic or post-traumatic

CT: Normal unless associated with trauma

MR: High T1 signal in inner ear fluid

Inner ear morphology: Inner ear looks like tilted “snowman” configuration on axial image

CT: Cochlea and vestibule cystic; bony vestibular aqueduct usually normal

MR: Both cochlea and vestibule are cystic; endolymphatic sac usually normal

CT: Complete or partial bony narrowing of base of cochlear nerve canal

MR: Fluid in cochlear nerve canal completely or partially replaced by low signal bone

Inner ear morphology: Inner ear looks like single cyst

CT: Single cyst with semicircular canals and vestibular aqueduct blended in

MR: Single inner ear fluid-filled cyst

CT: Cochlea absent with variable deformity of vestibule, semicircular canals and vestibular aqueduct

MR: Absent cochlea and cochlear nerve

Clinical clues: Blue sclera; mild form develops deafness by age 40 years

Imaging same as cochlear otosclerosis

CT: Active disease shows lucent foci in otic capsule surrounding cochlea

MR: Active disease shows enhancing foci in otic capsule

Clinical clues: Auricular deformity, prehelical pits, mixed hearing loss, branchial fistulae and renal abnormalities

Genetics: 40% with clinical manifestations have mutations of EYA1 gene on chromosome 8q13.3

CT: Hypoplastic apical turn of cochlea, medial deviation of facial nerve, funnel-shaped IAC and patulous eustachian tube

Clinical clues: Male child with bilateral mixed conductive and SNHL

CT: Cochlear nerve canal is enlarged with no modiolus