[Evaluation of the infants' hearing loss in hearing screening].

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.

[Evaluation of eustachian tube function with impedance audiometry in chronic suppurative otitis media].

OBJECTIVE: To evaluate the Eustachian tube function with impedance audiometry of the various types, durations and status of chronic suppurative otitis media. METHOD: The Eustachian tube functions of 368 patients (402 ears) of chronic suppurative otitis media were measured by the manual model of reading meter and regulating air pressure with impedance audiometry. The data were analysed statistically. RESULT: The average positive opening pressure of Eustachian tube was (23.5-8.3) daPa in expedite status, (79.8+/-16.2) daPa in mild obstruction, (154.1+/-28.7) daPa in serious obstruction and >200 daPa in entire obstruction. The percentage of detection was 50.5% in expedite status, 26.9% in mild obstruction, 11.9% in serious obstruction and 10.7% in entire obstruction, which in expedite status was much higher than that in various types of Eustachian tube obstruction status. However, the incidence of Eustachian tube opening in the cases with duration of 3 month-1 year was significantly lower than that in the cases with other durations. The opening pressure of Eustachian tube in the cases with large perforation of tense part of tympanic membrane was significantly lower than that in the cases with small perforation of tense part of tympanic membrane and perforation of flaccid part of tympanic membrane. Nevertheless, the incidence of Eustachian tube obstruction in the cases with large perforation of tense part of tympanic membrane was significantly lower than that in the cases with small perforation of tense part of tympanic membrane and perforation of flaccid part of tympanic membrane. CONCLUSION: The Eustachian tube was expedite in about 1/2 of cases with chronic suppurative otitis media, mild obstruction in about 1/4 quarter of cases, and serious obstruction and entire obstruction in about 1/10 of cases respectively. The Eustachian tube function was related to the duration, type and location of tympanic perforation in chronic suppurative otitis media. It is a simple, invasion-free method to evaluate the Eustachian tube function of chronic suppurative otitis media with impedance audiometry.