OBJECTIVE: To analyze the confusing factors and clinical and audiological characteristics of ABR and tympanometry in infants who failed the first and second hearing screening. METHOD: Between August 2005 and November 2007, 94 infants (144 ears) with detailed birth record and hearing screening record were reviewed in the study. The age of this series ranged from 48 days to 6 months. They received hearing screening with otoacoustic emissions (OAE), and all failed in the first and second hearing screening. The birth history, high-risk factors of hearing-impaired during newborn period and pregnancy history of subjects were fully detailed. Subjects were classified according to the age: 1 to 3 months old infants were considered as group 1, while 4 to 6 months old infants were considered as group 2. Auditory brainstem response (ABR), distortion product otoacoustic emissions (DPOAE) and acoustic immittance measurement were examined. RESULT: (1) The 226 Hz tympanograms of 144 ears showed type A of a single-peaked tympanogram in 77 ears (53.4%), a double-peaked tympanogram in 23 ears (16.0%), type Ad of a single-peaked tympanogram in 20 ears (13.9%), type As of a single-peaked tympanogram in 16 ears (11.1%), a flat-shaping tympanogram (type B) in 6 ears (4.2%), and others shapes (including C and D type) in 2 ears (1.4%). (2) The results of ABR showed that there were 64 ears (44.4%) with normal hearing (according to the threshold of ABR), 58 ears (40.3%) with mild hearing loss, 12 ears (8.3%) with moderate hearing loss, 3 ears (2.1%) with severe hearing loss, 7 ears (4.9%) with profound hearing loss. And the proportion of mild hearing loss was increased in the group, while the proportion of moderate and severe hearing loss was decreased. (3) The proportion of type A tympanogram was 50% (32 ears) in normal hearing subjects, which implied that the 226 Hz probe tones to record tympanogram would lead to a high false negative rate. And type proportion of type B tympanogram was higher in normal (4.7%) and mild hearing loss (3.4%) groups than in moderate and severe group. CONCLUSION Middle ear function and development of auditory system in infants may be confusing factors in hearing screening. The 226 Hz probe tones to record tympanogram are unreliable for accurate assessment of middle ear status of infants. Therefore the results of hearing screening should be interpreted appropriately.
Acoustic Impedance Tests ; Ear, Middle ; physiopathology ; Evoked Potentials, Auditory, Brain Stem ; Female ; Hearing Loss ; Hearing Tests ; Humans ; Infant ; Infant, Newborn ; Male ; Neonatal Screening ; Otoacoustic Emissions, Spontaneous