Study of hearing features of Congenital Malformation of the Middle and Outer Ear (CMMOE).

There is no study on the hearing features of congenital malformation of middle and outer ears (CMMOE), including classification, grades, and frequency characteristics, which play a decisive role in the selection of precise hearing solutions for patients. To analyze the hearing features of CMMOE and provide guidance for clinical practice. 298 cases (351 ears) with CMMOE were retrospectively analyzed for the features of 0.5 ∼ 4KHz pure tone hearing, including the classification, grades and frequency characteristics. We observed conductive deafness in 84.3% (296/351), mixed deafness in 15.7% (55/351), and 0% (0/351) sensorineural deafness. Grades measured by average Air Conduction Thresholds (ACT) of pure tone: Mild deafness (26-40dB HL) 0.6% (2/351), moderate deafness (41-55dB HL) 10.3% (36/351), moderate to severe deafness (56-70dB HL) 46.1%(162/351), severe deafness (71-90dB HL) 39.9%(140/351), extremely severe deafness (> 90 dB HL) 3.1%(11/351). The average ACT of 296 ears conductive deafness was 67 ± 10 dB HL, of which 56-80dB HL accounted for 78.1% (274/351). In 55 ears with mixed deafness, 32 ears (32/55 = 58.2%) increased Bone Conduction Threshold (BCT) at a single frequency, and out of 32 ears, 31ears (31/55 = 56.4%) ≤40dB HL, 25(25/32 = 78.1%) ears at 2KHz. In 55 ears with mixed deafness, 87.3% (48/55) increased BCT at 2KHz, and the average BCT was 35 ± 10dB HL. CMMOE result mainly in conductive deafness, moderate to severe and severe deafness. In mixed deafness, the BCT increased mainly at a single frequency, 2KHz and ≤40dB HL. These data suggest that bone-conductive hearing devices are a good solution for CMMOE hearing impairment.