62.1 Inner Ear

• Common in those with SNHL; may involve membranous, bony, or both parts of labyrinth (former probably most common but do not show on imaging)

• Various classification systems—Jackler et al (1987) based on their occurrence in embryogenesis; most likely to arise between 4–8/40

• Michel aplasia: arrest of inner ear development before 4/40—complete aplasia of all inner ear structures; associated with thalidomide exposure, anencephaly, Klippel–Feil syndrome; total SNHL, not candidate for CI

62.1.1 Cochlear Anomalies

• Common cavity: failure at 4/40, with membranous labyrinth poorly differentiated in a large common cavity; severe to profound HL; can try CI (risk CSF gusher)

• Cochlear aplasia: failure at 5/40; rare; normal vestibular development; profound SNHL, unlikely candidate for CI

• Cochlear hypoplasia: failure at 6/40 with variable HL

• Mondini dysplasia; failure at 7/40, with incomplete partition of cochlea so only basal turn cochlea present (most common cochlear malformation seen on imaging) with variable HL (some high-tone residual hearing possible); may be associated with widened vestibular aqueduct, some associated with stapes footplate anomalies, Waardenburg, DiGeorge, Pendred syndromes

• Widened vestibular aqueduct: definition varies, e.g., ≥1.5 mm; may be associated with Pendred and branchio-otorenal syndrome, cochlear dysplasias, or stapes fixation; often normal hearing at birth with progressive SNHL, sometimes sudden after mild HI; avoid HI/pressure changes (flights, diving); 30% have vestibular disturbance; autosomal recessive

62.1.2 Vestibular Anomalies

• Aplasia or dysplasia of lateral Scc most common (because develops later than other Sccs); may be associated with CHARGE (coloboma, heart defects, atresia of nasal choanae, retardation of growth, genital and/or urinary abnormalities, ear abnormalities and deafness) syndrome (which also has stenotic cochlear aperture, underdeveloped vestibule, incomplete partition of cochlea)

62.1.3 Membranous Anomalies

• Occur in isolation or with bony labyrinthine anomalies (because do not show on imaging, only determined histologically)

Bing–Siebenmann malformation: isolated membranous malformation within well-formed bony capsule; profound SNHL; associated with Usher and Jervell–Lange-Nielsen syndromes

Scheibe malformation: most common membranous inner ear malformation—malformed organ of Corti and saccule; severe to profound SNHL; associated with Usher, Jervell–Lange-Nielsen, Refsum, Waardenburg, trisomy 18; autosomal recessive inheritance

Alexander malformation: least severe—dysplastic basal turn of cochlea; high-frequency SNHL

62.2 Middle Ear

• Numerous ossicular abnormalities; malleus head fixation most common (due to incomplete pneumatization of epitympanum)

• Persistent stapedial artery: 2nd arch remnant, should regress at 10/40; if it does not, passes over stapes footplate; may be associated with aberrant course of ICA

• High jugular bulb

• Facial nerve: aberrant course most likely in presence of other congenital abnormalities

62.3 External Ear

• Microtia

1:10,000, M>F, R>L-hand side; 4:1 unilateral: bilateral

Association with other congenital abnormalities in ~50% cases (e.g., Treacher–Collins, Goldenhar, hemifacial microsomia) and teratogens (e.g., thalidomide)

Weerda classification:

– 1st degree dysplasia: most structures of normal auricle recognizable

– 2nd degree: some recognizable structures but additional skin/cartilage required for reconstruction

– 3rd degree: no normal structures seen so total reconstruction required

Rx: do nothing; minor malformations can be excised/repaired with flaps; consider autogenous reconstruction (e.g., using rib cartilage) or prosthesis; bone conduction hearing aid

• Pre-auricular tags and accessory auricles

Usually anterior to tragus

If cartilage present = accessory auricle

Often bilateral; may be part of a syndrome (e.g., Goldenhar)

Beware excision in children as VII n may be involved in root of accessory auricle