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Microtia

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Dysmorphology Presentations/Head and face

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A newborn with a small or malformed external ear, graded from mild structural anomaly (grade I) to absent ear (anotia, grade IV). The clinical relevance is hearing, syndrome detection, and surgical reconstruction. The first bedside decisions are whether the auditory canal is patent (atresia means conductive loss until surgical correction or bone-anchored device) and whether the malformation is unilateral or bilateral.

Two clinical splits drive the differential:

  1. Unilateral vs bilateral. Unilateral microtia (most often right-sided) is more often isolated or part of hemifacial microsomia / Goldenhar. Bilateral microtia is much more often syndromic.
  2. Is the canal patent? External auditory canal atresia accompanies most grade III microtia and produces a maximal conductive hearing loss (~60 dB). Bone-anchored hearing aids in infancy preserve speech development; reconstruction is staged in later childhood.

A careful exam of the contralateral ear, the face for asymmetry, the eyes for coloboma or epibulbar dermoid, the spine for hemivertebrae, the heart, and the kidneys narrows the differential fast.

Hemifacial microsomia and the OAVS spectrum

  • Hemifacial microsomia / craniofacial microsomia / Goldenhar (oculo-auriculo-vertebral spectrum): the most common syndromic association with microtia. Sporadic, usually unilateral, with hemifacial hypoplasia + ipsilateral microtia + epibulbar dermoid + vertebral anomalies (hemivertebrae). Cognition usually normal. Cardiac and renal anomalies in a subset.

Mandibulofacial dysostoses

  • Treacher Collins syndrome (TCOF1, POLR1C, POLR1D): bilateral and symmetric microtia + downslanting palpebral fissures + lower-lid coloboma + mandibular hypoplasia + conductive hearing loss. Symmetry is the distinguishing exam feature versus Goldenhar's asymmetry. Cognition normal.
  • Nager syndrome (acrofacial dysostosis) (SF3B4, AD): Treacher-Collins-like facies plus preaxial upper limb anomalies (radial hypoplasia, absent or hypoplastic thumbs). The limb finding makes the diagnosis. (No condition leaf to link.)

Branchial-arch and renal syndromes

  • Branchio-oto-renal (BOR) syndrome (EYA1, SIX1, SIX5, AD): preauricular pits + branchial cleft fistulae (lateral cervical sinuses) + microtia or other ear anomalies + sensorineural or mixed hearing loss + renal anomalies (agenesis, hypoplasia, dysplasia). Renal ultrasound is mandatory.
  • Townes-Brocks syndrome (SALL1, AD): ear anomalies (often satyr-ear shape) + imperforate anus + thumb anomalies (preaxial polydactyly or triphalangeal thumb) + renal anomalies. The ear-anus-thumb triad is the mnemonic. (No condition leaf to link.)

CHARGE syndrome

  • CHARGE syndrome (CHD7, AD; de novo in most): Coloboma + Heart defects + Atresia of choanae + Retardation of growth/development + Genital hypoplasia + Ear anomalies (cup-shaped, hypoplastic semicircular canals on imaging). Microtia in CHARGE is often paired with vestibular dysfunction (absent semicircular canals on temporal bone CT) and sensorineural hearing loss, in contrast to the conductive loss of microtia + canal atresia.

Other associations

  • Wildervanck syndrome: Klippel-Feil cervical vertebral fusion + bilateral abducens palsy + sensorineural hearing loss; female-predominant. (No condition leaf to link.)
  • Microtia in fetal isotretinoin exposure: maternal teratogen history is the clue.
  • Hemifacial microsomia after maternal diabetes: less specific association but documented.
  • Unilateral microtia + hemifacial hypoplasia + epibulbar dermoid + hemivertebrae → hemifacial microsomia / Goldenhar.
  • Bilateral symmetric microtia + lower-lid coloboma + downslanting fissures + small jaw, normal cognition → Treacher Collins.
  • Microtia + preauricular pits + branchial sinuses + renal anomaly → branchio-oto-renal syndrome.
  • Microtia + imperforate anus + thumb anomalies → Townes-Brocks (SALL1).
  • Cup-shaped ears + coloboma + heart defect + choanal atresia + absent semicircular canals → CHARGE (CHD7).
  • Treacher-Collins-like face + absent thumbs → Nager syndrome.

The exam guides which directed work-up to send first. A reasonable opening battery for any newborn with microtia:

  1. Otologic exam: grade the microtia (Marx I-IV), examine canal patency.
  2. Hearing evaluation: ABR (auditory brainstem response) in the first weeks; cATEC (auditory-evoked) or distortion-product OAE only if canal is patent.
  3. Temporal bone CT: middle and inner ear architecture, planning for hearing reconstruction and CHARGE evaluation (semicircular canals).
  4. Renal ultrasound: BOR, CHARGE, Townes-Brocks, Goldenhar.
  5. Echocardiogram: CHARGE, 22q11.2, Goldenhar.
  6. Spine films / MRI: hemivertebrae (Goldenhar), Klippel-Feil (Wildervanck).
  7. Ophthalmologic exam: coloboma (CHARGE), epibulbar dermoid (Goldenhar).
  8. Chromosomal microarray for syndromic features.
  9. Targeted gene testing: CHD7 for CHARGE, EYA1/SIX1 for BOR, SALL1 for Townes-Brocks, TCOF1/POLR1C/POLR1D for Treacher Collins, SF3B4 for Nager.
  10. Bone-anchored hearing aid (BAHA) softband in infancy if bilateral conductive loss; surgical reconstruction or osseointegrated implants in later childhood.
  • Bilateral microtia is much more often syndromic than unilateral. A unilateral pinna deformity in an otherwise well newborn is most often Goldenhar or isolated.
  • Treacher Collins is symmetric; Goldenhar is asymmetric. That single observation triages the differential fast.
  • Always image the kidneys in microtia + ear pits or fistulae. BOR and Townes-Brocks both have surgical renal disease that benefits from early detection.
  • Hearing intervention in the first months matters for speech. A BAHA softband bridges the gap until reconstructive surgery; don't wait years.
  • CHARGE ears are cup-shaped with absent semicircular canals. The vestibular finding on temporal bone CT often clinches the diagnosis when other CHARGE features are mild.
  • The ear-anus-thumb triad is Townes-Brocks. A child with microtia and imperforate anus gets SALL1 testing and a renal ultrasound.
  • Goldenhar is sporadic. Recurrence risk is low and reassurance is appropriate; the diagnosis is clinical and a normal microarray does not change the conclusion.
  • The contralateral ear matters. Always document its anatomy and check hearing bilaterally; subtle structural anomalies on the "good" side change the surgical and amplification plan.