OBJECTIVETo investigate the clinical classification and relationship with conductive deafness of congenital middle ear malformations.

METHODSFrom 1995 to 2004, 64 patients (82 ears) with single congenital middle ear malformations were operated in the ENT department of the General Hospital of Chinese People's Liberation Army. According to the histology and embryology of middle ear and the findings of surgical exploration, the clinical classification was performed. Statistical analysis was used to judge the differences of hearing loss in different type of congenital middle ear malformations.

RESULTSAccording to the embryologic development of the structures in middle ear, congenital middle ear malformations were classified 4 types. Type A: congenital ossicular chain anomalies; type B: congenital fusion of stapes; type C: congenital hypoplasia or atresia of oval/round widows. Hearing loss of three types on language frequency have no obvious difference (P = 0.1617), but there were statistical difference on high frequency ( > 2 kHz) between type A with type B and type C (P <0.05). Furthermore, descension of bone conduction and mixed deafness were familiar in type B and C.

CONCLUSIONSAccording to embryologic development, it was rational that congenital middle ear malformations were classed 3 types mentioned above. Hearing loss due to middle ear malformations could be distinguished by descension of bone conduction and air conduction on high frequency ( >2 kHz).