Congenital ear anomalies and microtia — branching viva

Branching viva on congenital ear anomalies and microtia: distinguishing a deformational deformity from a true microtia at the newborn check, grading by Marx, the embryology that explains why the inner ear is spared and the loss is conductive, the urgency of early bone-conduction hearing in bilateral aural atresia, the newborn molding window, the Jahrsdoerfer CT grading for atresiaplasty, and the syndromic associations of Treacher Collins, hemifacial microsomia and branchio-oto-renal.

branching clinical structured oral2 min readVerification in progress

Prompt

Outpatient clinic: a two-day-old with an unusual right ear that is a peanut-shaped vestige with a lobule and no external canal, a normal left ear, and a right-side refer on the newborn hearing screen. The examiner asks: what is the grade and the canal problem, what hearing loss do you expect and why, and what is the pathway — then branches to the molding decision for a folded complete ear, to a second newborn with bilateral microtia and a small chin, and finally to a child with a preauricular pit and a family history of renal disease.

Branch 1 — The grade, the canal and the hearing

The candidate should grade the right ear as Marx grade III microtia (a peanut-shaped vestige with a lobule but no recognisable architecture), the commonest grade, and identify the absent external canal as aural atresia. The expected finding is a conductive hearing loss on the right with a preserved sensorineural threshold, confirmed by ABR. [1]

Probe the embryology: the outer and middle ear develop from the first and second pharyngeal arches and the first pharyngeal cleft, so they fail together, while the inner ear develops separately from the otic placode of surface ectoderm and is usually spared — which is exactly why the loss is conductive, not sensorineural. Aural atresia blocks the conductive pathway to an intact cochlea, producing a maximal conductive loss of around fifty to sixty decibels. [1] [11]

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References5Show ledger

[1]Camison L; Lisk RC; Soldanska M Microtia: A Review. Clin Plast Surg, 2025.PMID 39986885
[6]Alanazi F; Almousa H; Alabdulkarim I; Alhamoudi A; Alruwaili R; et al Efficacy and Safety of Commercial Systems Versus Custom Procedures for the Nonsurgical Correction of Neonatal Ear Anomalies: A Systematic Review and Meta-Analysis. J Craniofac Surg, 2026.PMID 42223983
[3]Jahrsdoerfer RA; Yeakley JW; Aguilar EA; Cole RR; Gray LC Grading system for the selection of patients with congenital aural atresia. Am J Otol, 1992.PMID 1598988
[11]Cywka KB; Krol B; Skarzynski PH Effectiveness of Bone Conduction Hearing Aids in Young Children with Congenital Aural Atresia and Microtia. Med Sci Monit, 2021.PMID 34561413
[12]Marszałek-Kruk BA, Wójcicki P, Dowgierd K, et al. Treacher Collins Syndrome: Genetics, Clinical Features and Management. Genes (Basel), 2021.PMID 34573374