Peer Reviewed

Photoclinic

Unilateral Microtia in a Neonate

Authors:
Lynnette Mazur, MD, MPH; Mahak Saad, BS; and Lakshmi Konduru, BS
The University of Texas Health Science Center at Houston McGovern Medical School

Citation:
Mazur L, Saad M, Konduru L. Unilateral microtia in a neonate [published online April 20, 2018]. Consultant for Pediatricians.

 

A 4-month-old Hispanic girl presented to our clinic for a well-child visit.

History. Her medical history was significant for preterm delivery at 33 weeks of gestation, which had required a 3-week stay in the neonatal intensive care unit. At that time, she received diagnoses of a grade 2 intraventricular hemorrhage, atresia of the right ear, hypoplasia of the right mandible, and an atrial septal defect. Otoacoustic test results of the left ear were normal, but the atresia prevented testing of the right ear.

Physical examination. In our clinic, the infant’s weight was 4.5kg (1%), her length was 58.4 cm (3.8%), and her head circumference was 38 cm (2%). After adjusting for seven weeks of prematurity, the percentiles for weight, length, and head circumference were 15%, 50-75%, and 50% respectively. The physical examination findings were notable for plagiocephaly, atresia of the right ear with a pedunculated auricle (Figure), and hypoplasia of the right mandible.

 

Unilateral Microtia
Figure. The patient had microtia of right ear, visualized with pedunculated auricle.

 

Discussion. Ear malformations can be isolated defects or can be associated with other anomalies.1 Congenital atresia of the auricle, or microtia, impairs the functionality of the external auditory canal and the ossicles and impairs inner-ear nerve function. Risk factors include low birth weight, maternal insulin-dependent diabetes, and exposure to teratogens such as retinoic acid.2 In cases of microtia, conductive hearing loss occurs in 90% of the abnormal ears and 15% of the normal ears.1 There is a male predominance and a higher prevalence in individuals of Hispanic descent.2 Although microtia can occur bilaterally, approximately 90% of cases are unilateral.1 Microtia can present as an isolated finding or can be associated with macrostomia, renal and/or cardiac abnormalities, holoprosencephaly, and vertebral malformations.2 Syndromes that commonly present with microtia include Bixler syndrome, mandibulofacial dysostosis, and Meier-Gorlin syndrome.1

The pinna reaches 80% of its adult size by age 4 years, and pneumatization of the middle ear and mastoid process occurs between 4 and 6 years. Therefore, surgical correction is performed after these have occurred.3 However, because 40% of patients with unilateral hearing loss have a higher risk of speech delay, early childhood intervention with speech therapy is recommended starting at 4 months.1 Loss of higher-order processing in the brain occurs due to lack of binaural hearing and summation.3 Additionally, patients with right-sided microtia have an even higher risk of speech delay.4 This “right-ear disadvantage” stems from the contralateral nature of auditory pathway cortical routing, because the left auditory cortex is dominant in language processing.4 Patients with unilateral microtia also have increased rates of middle-ear effusion in the normal ear, which adds to hearing impairment.

Placement of tympanostomy tubes is common and requires close follow-up.5 For children with bilateral hearing loss exceeding 20 dB, bone-anchored hearing aids (BAHA) can be placed to avoid delayed language development.6 The BAHA system is most beneficial in patients whose anatomy restricts surgical reconstruction. It is implanted into the mastoid process and directs sound to the cochlea by bypassing the middle ear and external auditory canal.6 Ideally, the BAHA system is placed in patients aged 2 to 4 years. Younger patients have insufficient bone thickness to support cochlear implants, a longer time for adequate osseointegration, a higher likelihood of poor hygiene with improper care of the implant site, and a higher risk of the need for traumatic revision.6 For patients with these limiting factors, using the BAHA system with a soft band can be a temporary solution.6

Genetic testing for children with multiple anomalies is recommended by the American Academy of Pediatrics. Testing with chromosomal microarray analysis (CMA) has a significantly higher diagnostic yield (15%-20%) than conventional G-banding karyotype analysis (3%).5,7 CMA detects duplications and deletions of 10 to 100 KB of genetic material and requires cell culture, whereas karyotyping detects duplications or deletions in 5 to 10 MB and does not require cell culture.1 CMA can detect specific mutations in the long arm of chromosome 5 such as Treacher Collins and Goldenhar syndromes, which are both associated with microtia; karyotyping can detect Down syndrome, a less common cause of microtia.1 Our patient’s CMA and karyotype results were normal.

Conclusion. Our patient was referred to an early childhood intervention program for speech therapy. Ideally, the multidisciplinary team will include audiologists, otolaryngologists, speech pathologists, geneticists, and educational specialists, along with an ophthalmologist due to the possibility of primary reliance on vision.8

References:

  1. Luquetti DV, Heike CL, Hing AV, Cunningham ML, Cox TC. Microtia: epidemiology and genetics. Am J Med Genet A. 2012;158A(1):124-139.
  2. Canfield MA, Langlois PH, Nguyen LM, Scheuerle AE. Epidemiologic features and clinical subgroups of anotia/microtia in Texas. Birth Defects Res A Clin Mol Teratol. 2009;85(11):905-913.
  3. Zim SA. Microtia reconstruction: an update. Curr Opin Otolaryngol Head Neck Surg. 2003;11(4):275-281.
  4. Jensen DR, Grames LM, Lieu JEC. Effects of aural atresia on speech development and learning: retrospective analysis from a multidisciplinary craniofacial clinic. JAMA Otolaryngol Head Neck Surg. 2013;139(8):797-802.
  5. Ellison JW, Ravnan JB, Rosenfeld JA, et al. Clinical utility of chromosomal microarray analysis. Pediatrics. 2012;130(5):e1085-e1095.
  6. Farnoosh S, Mitsinikos FT, Maceri D, Don DM. Bone-anchored hearing aid vs. reconstruction of the external auditory canal in children and adolescents with congenital aural atresia: a comparison study of outcomes. Front Pediatr. 2014;2:5. doi:10.3389/fped.2014.00005.
  7. Miller DT, Adam MP, Aradhya S, et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. Am J Hum Genet. 2010;86(5):749-764.
  8. Lieu JEC. Unilateral hearing loss in children: speech-language and school performance. B-ENT. 2013;suppl 21:107-115.