**3. Hearing level**

The pure-tone hearing average (average air conduction threshold at 0.5, 1, and 2 kHz) is used as a representative value for the hearing level, and the normal hearing range is generally defined as greater than 20 dB with an air-bone gap within 15 dB. We investigated the hearing levels for our patients with congenital microtia and compared these hearing levels with Marx's classification results (**Table 2**). Marx's classification scores did not show a correlation with the pure-tone hearing level. A previous report also found that the hearing level in microtic ears does not correlate with the degree of microtia [7].

with chorda tympani nerve dysfunction did not have facial nerve paralysis. In addition, there was no significant difference in Jahrsdoerfer scores for the facial nerve between those with and without chorda tympani nerve dysfunction [5]. It is speculated that facial nerve paralysis, probably including chorda tympani nerve dysfunction, does not always correspond to an

Hearing Loss in Congenital Microtia http://dx.doi.org/10.5772/intechopen.72429 51

Because approximately 20–60% of patients with congenital microtia are known to have associated anomalies or an identifiable syndrome [8], patients with microtia should be examined for other dysmorphic features. In our patients, although there were no cases complicated by anomalies in the kidney and spine, there were some children complicated by esophageal atresia, ventricular septal defect, funnel chest, and cleft lip and palate. Especially, symptomatic microtia, which includes Goldenhar syndrome, hemifacial microsomia, trisomy 21, trisomy 18, and Treacher Collins syndrome, may have additional associated congenital anomalies.

Gorlin et al. [9] proposed an encompassing term "oculo-auriculo-vertebral spectrum (OAVS)," which is characterized by facial asymmetry, microtia, ear and facial tags, epibulbar dermoids, microphthalmia, and macrostomia. Hemifacial microsomia, Goldenhar syndrome, and all of its associated anomalies and variations are thought to be included in this spectrum. Extracranial features include renal, cardiac, and vertebral anomalies; at present, there is no consensus on the minimal diagnostic criteria for OAVS [10]. OAVS and microtia share the following characteristics: (1) variable phenotypic expression, (2) asymmetric involvement of facial structures, (3) right-side preponderance, (4) male predilection, and (5) familial occurrence of microtia or related anomalies, such as preauricular tags and pits [10]. Thus, isolated

The clinical expression of congenital microtia and OAVS overlap; hence, clinicians should consider multiple medical assessments when examining patients with microtia. First, all patients with microtia should have a diagnostic ear-specific hearing assessment within the first 6 months of age, to identify hearing loss and to assess the type and severity of hearing impairment. In children with conductive hearing loss, high-resolution CT examination of the temporal bone is useful for evaluating the middle and inner ear structures when the child is of preschool or school age. Renal ultrasound, cardiovascular examination at diagnosis, and cervical spine films at the age of 3 years are also recommended [11]. Treatment for atresia should be considered in the context of hearing, speech and language development, and reconstruc-

Since lack of landmarks, abnormal anatomies of the facial nerve and middle ear structures, and limited space for sound reconstruction, surgical correction of hearing improvement is sometimes difficult and challenging. Therefore, not only surgery but also hearing acquisition through the use of a device should be considered. To date, osseointegrated implants known as bone-anchored hearing aids (BAHA® by Cochlear) and active middle ear implants known as Vibrant Soundbridge® (VSB by Med-El) have been the most reliable method of hearing

anatomic abnormality of the nerve tract.

microtia represents a milder phenotype of OAVS.

tive surgery at approximately 10 years of age.

**5. Management of patients with congenital microtia**


**Table 2.** Average hearing level in patients with microtia.
