[The characteristic of enlarged vestibular aqueducts syndrome in pure tone audiometry: low frequency air-bone gap].
OBJECTIVE
The purposes of this study was to analyse the significant of low frequency air-bone gap in enlarged vestibular aqueduct (EVA) patients according to the pure tone audiogram and the benefit for clinic diagnosis of the EVA.


METHODS
The audiology testing include (1) play audiometry or pure tone audiometry, tympanometry, middle ear muscle reflex thresholds and stapedius muscle reflex; (2) High-resolution computed tomography (CT) scan of the temporal bone and magnetic resonance imaging was used for diagnoses the EVA.


RESULTS
All the 78 patients (154 ears) were diagnosed as the typical EVA by CT or MRI. Inner ear malformations were found in 3 ears otherwise the structures of middle ear in all the patients were absolutely normal. The audiology analysis showed 154 ears were type A tympanogram including 126 ears with typical A, 25 ears with As, 3 ears with Ad type. In the 250 Hz pure-tone test:A-B gap were observed in 126 ears(126/154,81. 8%) with the different hearing loss degree: 1 ear mild, 11 ears moderate, 19 ears moderate severe, 40 ears severe and 53 ears profound. In the 500 Hz pure-tone test: A-B gap were found in 102 ears(102/154, 66. 2%) with the different hearing loss degree: 9. ears moderate, 17 ears moderate severe, 35 ears severe and 41 ears profound.


CONCLUSIONS
Our study suggested a 66. 2% -81. 8% possibilities to find the EVA through the pure-tone audiometry firstly in the basis of the normal tympanograms with the significant A-B gap.
Lan
Lan
L
Department of Otolaryngology-Head and Neck Surgery,Chinese People's Liberation Army General Hospital, Beijing, 100853, China.
Wang
Qiuju
Q
Chen
Zhihui
Z
Ding
Haina
H
Zhao
Jiandong
J
Guo
Mingli
M
Yu
Liming
L
D000158:Acoustic Impedance Tests; D000293:Adolescent; D001301:Audiometry, Pure-Tone; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D014723:Vestibular Aqueduct; D015837:Vestibular Diseases / Q000503:physiopathology*