Relationship between congenital malformation of the outer ear and hearing

Background: There is no report on the relationship between congenital malformation of the outer ear and hearing, which makes it possible to predict the hearing level just based on microtia grades.Aims/Objectives: To investigate the correlation between two types of congenital malformation of the outer ear [microtia and Outer Ear Canal Malformation (OECM)] and hearing, as well as the interrelationship among all three variables.Material and methods: A total of 535 cases (598 ears) of congenital malformation of the middle and outer ear (CMMOE) with hearing data, out of which 319 cases (349 ears) microtia with available images and graded by I-V, 449 cases (482 ears) OECM graded by atresia, stenosis and normal, and 87 cases (87 ears) OEC atresia graded I-IV, 301 cases (301 ears) with materials of microtia, OECM and hearing at the same time were carried out correlation analysis. The Average Air-Conduction Threshold of pure tone (AACT) at 0.5-4 KHz was calculated corresponding to the ears with different malformation grades. The differences in AACT among different malformation grades, the correlation between malformation severity and AACT, as well as the relationship among microtia, OECM and AACT were analyzed. The one-way analysis of variance (ANOVA) was employed to compare the differences in AACT, Kendall's tau-b rank correlation coefficient test was used for correlation analysis. A statistical significance level of p < 0 .05 was applied.Results: Among the 349 ears with microtia, the corresponding AACT values for grades I to V were 61.6, 63.0, 69.9, 75.4, and 75.0 (dB HL), respectively. Comparing grade III to grades II or IV, both p < 0 .05. However, p > 0 .05 between grade I and II or between grade IV and V. The correlation coefficient between microtia grades and AACT r = 0.219, p < 0.05. Among the 482 ears of OECM, the distribution was as follows: 73.6% atresia, 19.1% stenosis, and 7.3% normal, the corresponding AACT values were 64.1, 61.7, and 52.5 (dB HL), respectively. Comparing normal to stenosis or atresia, both p < 0.05, while between atresia and stenosis p > 0.05. The correlation between OECM and AACT was r = 0.104, p < 0.05. The AACT values corresponding to grades I to IV of OEC atresia in the 87 ears were 59.9, 65.1, 71.1, and 64.1 (dB HL), respectively. Comparing these grades, all p > 0.05. The correlation between the degree of atresia and AACT r = 0.23, p < 0 .05. The correlation coefficients for 301 ears microtia to OECM, microtia to AACT, OECM to AACT were r = 0.339, r = 0.163 and r = 0.128 respectively, with all p < 0 .05.Conclusion and significance: There are positive correlations among the degree of microtia, degree of OECM, and AACT values for each other, and so between the degree of OEC atresia and AACT, suggesting that as the severity of microtia or OECM increased, the AACT also tended to be higher, which make it possible to predict the hearing level and the degree of OECM based on microtia grades in clinical practice. Additionally, there are significant differences in AACT values in microtia grade III to grades II or IV, OEC normal to stenosis or atresia, while no differences in microtia grade I to II and grade IV to V, OEC stenosis to atresia, and among the grades I-IV of the OEC atresia.