2.2 | Participants
645 children diagnosed with bilateral severe or profound sensorineural hearing loss in the Removed for Blind Peer Review were recruited in this study. Children were excluded if they had: 1) unable to completed the examination or evaluation; and 2) evidence of major secondary disabilities such as white matter diseases, nervous system disease, physical disability. Accordingly, 500 children were selected and all they completed auditory evaluation, CT scan of the temporal bone and developmental evaluation.
The CT scan was measured by the same specialized radiologist and the vestibular aqueduct, inner structure and internal auditory canal were paid special attention. The vestibular aqueduct was regarded as enlarged when midpoint diameter of vestibular aqueduct was >1.5 mm in the axial view in a computed tomography scan (2). LVAS could be diagnosed when enlarged vestibular aqueduct was a separate anomaly and those combined with other inner ear malformations were excluded in this study. Representative examples of CT are shown in FIGURE 1.
According to the results of CT scan, 70 children diagnosed with isolated enlarged vestibular aqueduct were recruited as LVAS group. Among the remaining subjects without enlarged vestibular aqueduct, we used propensity matched analysis (PSM), matching the factors of gender, age and hearing threshold, at the ration of 1:1, to screen the candidate for non-LVAS subjects. Finally, 70 gender-, age-, and auditory- matched children were recruited as non-LVAS group.