The Study Of Multi-frequency Tympanometries As Diagnostic Tests Of Middle Ear Function In Infants Aged From 0 Month To12 Months

Objective:An experimental analysis on the collected results of tympanometries of 226Hz, 678Hz and 1000Hz in infants aged from 0 month to 12 months, reconfirmed by results of auditory brainstem response (ABR) wave I latency and transiently evoked otoacoustic emissions (TEOAE), to evaluate the effect of multiple frequency tympanometries in diagnosing the middle ear function of infants at the corresponding age.Methods:A sample of 200 infants with normal middle ear function were divided into 4 groups of age:GROUP 1(0-28days), GROUP 2(1-3months, ±3days), GROUP 3(4-6months, ±7days), Group 4(7-12months, ±7days), each of which consisted of 50 infants. The subjects with abnormal middle ear function, totally 30 infants(57 ears), including 18 males and 12 females, were divided into 2 groups:GROUP 1(0-6 months) and GROUP 2(7-12 months). The tympanograms analysis of different age groups and differential frequency characteristics of multi-frequency tympanometries were obtained from both of the normal sample tympanograms and abnormal groups by using GSI TympStar 2 Middle-Ear analyzer.Results:For normal groups: ①by testing the 226Hz probe tone tympanometries Equivalent ear canal volume (Ecv) was increasing in sync with age while Tympanometric Peak Pressure (TPP) and Peak compensated static acoustic admittance (Ymt) were decreasing respectively. ② Comparatively the TPP and Ymt were increasing in sync with age under both 678Hz and 1000Hz probe tone tympanometries while the minimum result occurred in infants of GROUP 2(1-3months). In the same age group the provided data of TPP and Ymt for 1000Hz probe tone tympanograms were greater than data of 678Hz probe tone tympanograms. ③It was noted that frequency of probe tone and age imposed a remarkable impact on TPP and Ymt of tympanograms. ④ The resonance peak value of the external auditory canals was tested as 284±48Hz for group 1,293±51Hz for group 2,450±152Hz for group 3,650±205Hz for group 4.⑤For abnormal groups:in GROUP 1(0-6 months) the agreement rate of ABR wave I latency delay and TEOAE failure was 24.2%,93.9% and 87.9% under 226HZ,678Hz and 1000Hz probe tone respectively, of which the kappa statistic were 0.01,-0.11 and 0.49; in GROUP 2(7-12 months) the agreement rate of ABR wave I latency delay and TEOAE failure was 75%,91.7% and 91.7%, of which the kappa statistic were 0.02,0.89 and 0.89.Conclusion:The 226Hz probe tone tympanometries failed to evalue the function of middle ear for infants who were younger than 12 months. The 678Hz probe tone tympanometries failed to evalue the function of middle ear for infants who were younger than 6 months. It is suggested that the 1000Hz probe tone tympanometry should be used for evaluating the function of middle ear of infants who are younger than 6 months old. The 678Hz probe tone tympanometry is the supplementary option in case that the results of the 1000Hz probe tone tympanometry caused occlusion effect. And furthermore it is convincing that unless the 1000Hz probe tone tympanometry or 678Hz probe tone tympanometry has been tested otherwise the function of middle ear for infants who are between 7 and 12 months old cannot be evaluated precisely.