Congenital ear anomalies and microtia — branching viva

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]

Branch 2 — The molding decision and the newborn window

Introduce a second infant with a soft, structurally complete folded (lop) ear. The candidate should distinguish it from a malformation by palpation: the cartilage is soft, springy and complete, so it is a deformational deformity correctable by ear molding. The key is timing — molding must start in the first one to two weeks of life while circulating maternal oestrogen keeps the cartilage pliable, because the cartilage stiffens by six to eight weeks and success falls sharply. [6]

Push the candidate on the consequence of delay: a deformity correctable by a splint at day five becomes a surgical problem at week six, so missing the window is the classic error. By contrast, a true grade III microtia cannot be molded because tissue is missing, and it needs staged reconstruction. [6]

Branch 3 — The bilateral newborn and the syndromic child

Introduce a newborn with bilateral microtia, bilateral absent canals, a bilateral refer on the hearing screen, and a small recessed chin. The candidate should recognise this as the urgent presentation — bilateral aural atresia — and prioritise two things: urgent ABR and early bone-conduction hearing rehabilitation (a softband device) to protect the critical period for speech and language, and an airway assessment because the micrognathia and glossoptosis can obstruct the neonatal airway, raising Treacher Collins syndrome. [11] [12]

Introduce a four-year-old with a preauricular pit, an excised branchial sinus, and a family history of hearing loss and renal disease. The candidate should recognise branchio-oto-renal syndrome (EYA1), and name the renal ultrasound as the urgent investigation because the renal anomaly can be silent until renal failure. Close on the synthesis: hearing first, mold the moldable early, work up the syndromes, and stage the reconstruction by the Jahrsdoerfer score — a threshold of seven or more out of ten favouring atresiaplasty. [12] [3]