Participants
Retrospectively reviewed were the medical records of 1,251 patients who underwent CI to treat profound hearing loss between August 2001 and March 2021.All patients suffered severe or very severe bilateral sensorineural hearing loss (HL, defined as hearing threshold > 70 dB HL). Before the initial CI, assessments were conducted of acoustic impedance, auditory brainstem response, distortion product otoacoustic emissions, transient evoked otoacoustic emissions, auditory steady state response. Middle ear high-resolution CT (HRCT) and inner ear magnetic resonance hydrography were performed to rule out the deformity in middle and inner ears, middle ear mastoiditis, tympanic effusion, or other infections before operation. Brain MRI examination was conducted to reveal potential white matter lesions and CI was considered for those cases with mild and non-progressive white matter lesions.